Researching On Toyota Vios 2022 2Nr-Fe Engine Control System.pdf

GRADUATION THESIS AUTOMOTIVE ENGINEERING TECHNOLOGYMINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION Ho Chi Minh City, January 2024RESEARCHING O

OVERVIEW

Reasons for choosing the topic

In recent years, Vietnam's economy has been developing strongly Besides our country's technology is also gradually progressing Including the powertrain and automobile manufacturing industry, we have joint ventures with many famous companies in the world for rapid production and assembly To support the improvement of qualifications and techniques, our team of engineers must research and manufacture themselves, which is an equipment level requirement There are many details about us that make us interested in the development of countries in the region and around the world

Therefore, our team carried out the project: RESEARCHING ON TOYOTA VIOS

2022 2NR-FE ENGINE CONTROL SYSTEM, to help students have a more detailed view of engines while improving their understanding, about the structure and principles of engine control systems Beside, we bring detailed in systems inspection and repair follow manufacturer documents.

Research purposes

The aim of the project is to research a model of vehicle for inspection, evaluation and repairing analysis base on its parameters that addresses the need for enhanced knowledge about new internal combustion engine The primary goal is to combine the data availability from various parameters in Toyota manual book and leverage advanced computer vision and machine learning techniques to accurately detect and evaluate vehicles in real time, while also analyzing their repairing method By achieving this aim, we aim to provide timely knowledge and information for drivers about the chosen model

Furthermore, the project aims to enhance overall information about the working principle by utilizing modern engine and methodologies for panoptic driving perception The accurate and reliable identification of vehicles in various environment conditions is vital for building a solid foundation for subsequent research

Toyota Vios 2022 Engine Control Systems

In this research, our group would like to bring the details of control system of 2NR-

FE engine In control system we focus on the fuel injection system, ignition system and sensors But there are many sensors on the 2NR-FE engine so we will discover these sensors mentioned below:

The main research method is the method of document synthesis Document synthesis is a method of linking each aspect and each part of information from the collected documents to create a complete and in-depth understanding of the research topic Document synthesis is performed on many documents rich in subjects Document synthesis is performed on the basis of document analysis results, allowing researchers to have comprehensive and general information about the research problem based on existing documents In our project, we collect information from many sources then rearrange them into our for comprehensive and general information about the research of Toyota Vios

2022 2NR-FE engine control system.

Research scope

In this research, our group would like to bring the details of control system of 2NR-

FE engine In control system we focus on the fuel injection system, ignition system and sensors But there are many sensors on the 2NR-FE engine so we will discover these sensors mentioned below:

Research method

The main research method is the method of document synthesis Document synthesis is a method of linking each aspect and each part of information from the collected documents to create a complete and in-depth understanding of the research topic Document synthesis is performed on many documents rich in subjects Document synthesis is performed on the basis of document analysis results, allowing researchers to have comprehensive and general information about the research problem based on existing documents In our project, we collect information from many sources then rearrange them into our for comprehensive and general information about the research of Toyota Vios

2022 2NR-FE engine control system

OVERVIEW OF TOYOTA

Introduce of Toyota

The history of Toyota started in 1933 with the company being a division of Toyoda Automatic Loom Works devoted to the production of cars under the direction of the founder's son, Kiichiro Toyoda Kiichiro Toyoda had traveled to Europe and the United States in 1929 to investigate automobile production and had begun researching gasoline- powered engines in 1930 Toyoda Automatic Loom Works was encouraged to develop automobile production by the Japanese government, which needed domestic vehicle production, due to the war with China [1]

Kiichiro Toyoda seized this opportunity to establish the Automotive Production Division on September 1, 1933, and began preparing to build prototype vehicles In 1934, the division produced its first Type A Engine, which was used in the first Model A1 passenger car in May 1935 and the G1 truck in August 1935 Production of the Model AA passenger car started in 1936 Early vehicles bear a striking resemblance to the Dodge Power Wagon and 1930's Chevrolet, with some parts actually interchanging with their American originals [1]

The first few months of the Korean War resulted in an order of over 5,000 vehicles from the US military, and the company was revived Ishida was credited for his focus on investment in equipment One example was the construction of the Motomachi Plant in

1959, which gave Toyota a decisive lead over Nissan during the 1960s [1]

Toyota was the first to make hybrid cars, which use both gas and electricity, in 1997

It made the Prius, which was the first hybrid car in the world It also made the Mirai, which was the first car that used hydrogen as fuel, in 2014 [1]

Toyota became the biggest car maker in the world in 2008 It also cared a lot about the environment and society It made the Toyota Environmental Challenge 2050, which

24 was a plan to reduce the harm that cars cause to the planet It also wanted to become a mobility company, which means it would make more than just cars It would also make robots, artificial intelligence, and smart cities [2]

Figure 2.1: World Car Maker in 2008

Toyota celebrated its 80th birthday in 2020 It was proud of its history and its achievements It also looked forward to the future and its new challenges

Toyota Motor Sales U.S.A., Inc.: "To attract and attain customers with high-valued products and services and the most satisfying ownership experience in America [3]

Toyota Global: While not explicitly stated as a single sentence, Toyota's global vision encompasses elements of "Producing Happiness for All" and "Creating Mobility for All." These goals guide the company's efforts to provide safe, reliable, and sustainable transportation solutions that enhance lives [4]

Toyota Motor Sales U.S.A., Inc.: "To be the most successful and respected car company in America." [3]

Toyota Global: "To lead the future mobility society, enriching lives around the world with the safest and most responsible ways of moving people." This vision emphasizes not just car manufacturing but also embracing innovation and technology to shape a future with accessible and environmentally conscious mobility solutions [4]

Toyota has a wide range of cars available, from subcompact sedans to full-size SUVs Toyota's car lineup from the bottom to the top:

• Subcompact sedans: The Toyota Vios and Yaris are both subcompact sedans that offer affordability and fuel efficiency They are good choices for first-time car customer or those who are looking for a practical and reliable car

• Compact sedans: The Toyota Corolla and Camry are both compact sedans that offer a good balance of performance, fuel efficiency, and features They are good choices for families or those who are looking for a car that is both fun to drive and practical

• Midsize sedans: The Toyota Avalon and Camry Hybrid are both midsize sedans that offer a more spacious and comfortable interior than compact sedans They are good choices for those who need a car with more room or who want to save on fuel costs

• Large sedans: The Toyota Mirai and Crown are both large sedans that offer a luxurious and comfortable driving experience They are good choices for those who want the best of the best in terms of performance, features, and comfort

• SUVs: Toyota offers a wide range of SUVs, from subcompact SUVs to full-size SUVs The Toyota Raize, Yaris Cross, RAV4, Highlander, and Sequoia are all good choices for different needs

Introduce of Vios

The Toyota Vios is a nameplate used for subcompact cars produced by the Japanese manufacturer Toyota, primarily for markets in Southeast Asia, China and Taiwan since

2002 Ranked below the compact Toyota Corolla, Vios serves as the replacement to the Tercel (marketed as Soluna in Thailand since 1997 and Indonesia since 2000), which filled the B-segment sedan class in the market [5]

The "Vios" name is derived from the Latin word "vio", meaning "go or travel (forward)", while Toyota marketed the car in Indonesia in 2007 with the backronym "Very Intelligent, Outstanding Sedan" In Indonesia, downgraded models of the Vios to cater for taxi fleet was marketed as the Toyota Limo through three generations [5]

The Toyota Vios is a subcompact sedan that was first introduced in Thailand in 2002

It was originally known as the Toyota Yaris Ativ, but was renamed Vios in 2006 The Vios is now sold in over 150 countries around the world, and is one of the best-selling subcompact sedans in the world [5]

The first-generation Vios was based on the platform of the Toyota Yaris hatchback

It was powered by a 1.3-liter four-cylinder engine and was available in both manual and automatic transmission options The Vios was praised for its fuel efficiency, reliability, and affordability [5]

Figure 2.2: Toyota Vios First Generation

The second-generation Vios is a renamed Japanese market Belta sedan with varying trim levels and equipment sold in Southeast Asian countries between April 2007 and March

2013 It was also sold as the Yaris sedan in North America and Australia The model received a facelift in mid-2010 and the second time in 2012 [5]

Figure 2.3: Toyota Vios Second Generation

The third-generation Vios (designated XP150) for the Asian market was unveiled on

25 March 2013 at the 34th Bangkok International Motor Show in Thailand Its design was previewed by the Dear Qin sedan concept that was first displayed at the April 2012 Auto China Toyota aimed to designate the third-generation Vios as a global model, for markets outside of Asia The car was sold in Thailand shortly after, and from the second quarter in Asia The exterior was enlarged over the front and rear sections and its styling outline was later followed by the XP150 series Yaris hatchback for the Southeast Asian market The instrument cluster position is no longer mounted on the center of the dashboard [5]

Figure 2.4: Toyota Vios Third Generation

The fourth-generation Vios (designated AC100) debuted on 9 August 2022 in Thailand as the Yaris Ativ (the "Vios" nameplate had discontinued there) It is developed by Daihatsu through a joint Toyota-Daihatsu internal company known as Emerging-market Compact Car Company (ECC) under the lead of executive chief engineer Hideyuki Kamino [6]

Figure 2.5: Toyota Vios Fourth Generation

The Toyota Vios has been a popular choice for subcompact sedan buyers around the world thanks to its fuel efficiency, reliability, affordability, and spacious interior It is also one of the safest subcompact sedans on the market, with a number of standard safety features, including electronic stability control, traction control, and airbags

In the past few years, Vios occupies the main part of cheap automobile genre in Vietnam because of its core values in comparison with its reasonable price

Figure 2.6: Toyota Vios Market Share in June 2023 in Vietnam

To provide customers with a reliable, affordable, and fuel-efficient subcompact sedan that is also safe and spacious

To be the leading subcompact sedan in the world by offering a superior driving experience and value to customers

The Toyota Vios mission statement is focused on providing customers with a practical and affordable sedan that meets their needs The vision statement is more aspirational, aiming for the Vios to be the best subcompact sedan on the market

The Vios mission and vision statements are aligned with the overall mission and vision of Toyota Motor Corporation, which is to provide safe, reliable, and efficient vehicles to customers around the world

How the Vios mission and vision statements are reflected in the car:

• Reliability: The Vios is known for its reliability and durability It has a number of features that contribute to its reliability, such as a strong engine, a durable transmission, and a well-built chassis

• Affordability: The Vios is one of the most affordable subcompact sedans on the market It offers a good value for the price, with a number of standard features that are not available on other subcompact sedans at the same price point

• Fuel efficiency: The Vios is relatively fuel-efficient for a subcompact sedan It gets good fuel economy in both city and highway driving

• Safety: The Vios is one of the safest subcompact sedans on the market It comes standard with a number of safety features, including electronic stability control, traction control, and airbags

Overall, the Toyota Vios mission and vision statements are reflected in the car's reliability, affordability, fuel efficiency, safety, and spacious interior

These rivals offer similar features and performance to the Vios, but they may have different strengths and weaknesses For example, the Honda City is known for its fuel efficiency and reliability, while the Hyundai Accent is known for its value and features The Mazda 2 is known for its sporty handling and fun driving experience, while the Nissan Almera is known for its spacious interior and comfortable ride The Suzuki Ciaz is known for its affordable price and fuel efficiency

Ultimately, the best way to decide which subcompact sedan is right for you is to test drive a few different models and see which one you like the best

Table 2.1: Shape and Size of Vios 2022

Max Power 107 hp at 6000 rpm

Max Torque 140 Nm at 4200 rpm

Gearbox Manual 5-speed or A/T CTV

Drive system Front Wheel Drive

Suspension System Independent MacPherson strut/Torsion Beam

Rear Brake Drum Brake/Disc Brake

2NR-FE is a 1.5 L (1,496 cc) variant of the NR series engine, first introduced in the fourth quarter of 2010 for the Toyota Etios It is the first new engine Toyota developed for over 8 years without VVT-i made to lower costs for the Toyota Etios A new innovation was introduced to this engine with the integration of the exhaust manifold into the cylinder head to reduce emissions A Dual VVT-i equipped version was later introduced and first used in Toyota Avanza and in many 1.5L models in the Asian market from the 2017 model [7]

The Toyota NR engine family is a series of small inline-four piston engines designed and manufactured by Toyota, with capacities between 1.2 and 1.5 liters (1,197 and 1,498 cc) [7]

The NR series uses alunium engine blocks and cylinder head The valve mechanism is equipped with 4-Valves per cylinder, DOHC, and implemented Toyota's Dual VVT-i and VVT-i It also uses multi-point or direct fuel injection The 1NR, 2NR, 3NR, 4NR, 5NR, 6NR, and 7NR engines have Dual VVT-i standard and the 8NR engine has VVT-i,

32 enabling it to operate in the Otto cycle as well as a modified Atkinson cycle to improve thermal efficiency [7]

Technical specifications of the engine:

• Bore x Stroke: 72.5 mm × 90.6 mm (2.85 in × 3.57 in)

• 66 kW (90 PS; 89 bhp) at 5600 rpm (w/o Dual VVT-i)

• 79 kW (107 PS; 106 bhp) at 6000 rpm (with Dual VVT-i)

• 132 N⋅m (97 lbf⋅ft) at 3000 rpm (w/o Dual VVT-i)

• 140 N⋅m (103 lbf⋅ft) at 4200 rpm (with Dual VVT-i)

• Compression ratio: 11.5:1; Indonesian Euro 3 version: 10.5:1

Applications: Toyota Etios, Toyota Sienta, Toyota Vios/ Yaris/ Limo

The K312 CVT transmission is a continuously variable transmission that is used in the Toyota Vios It is a relatively new transmission, having been introduced in 2019 The K312 CVT is designed to be more fuel-efficient and responsive than previous generations of CVT transmissions [8]

Specs of the Toyota K312 CVT transmission:

• Type: Continuously variable transmission (CVT)

• Final drive ratio: 5.698:1 (when fitted to 1.5L Allion & Premio 1NZ-FE and 1.8L Corolla 2ZR-FE)

• 5.356:1 (when fitted to 1.8L Allion & Premio 2ZR-FE)

The K312 CVT uses a number of new technologies to achieve its improved performance One of these technologies is a new pulley design that allows for a wider range of gear ratios This gives the K312 CVT more flexibility to match the engine speed to the road speed, which improves fuel efficiency and responsiveness

Electronic ignition system

Ignition system, in a gasoline engine, means employed for producing an electric spark to ignite the fuel–air mixture; the burning of this mixture in the cylinders produces the motive force [9]

The basic components in the ignition system are a storage battery, an induction coil, a device to produce timed high-voltage discharges from the induction coil, a distributor, and a set of spark plugs The storage battery provides an electric current of low voltage (usually 12V) that is converted by the system to high voltage (40,000 V) The distributor routes the successive bursts of high-voltage current to each spark plug in the firing order [9]

Strong spark: In the ignition system it is necessary to create a voltage of ten of thousands of volts to ensure a strong spark that can ignite the air mixture

Precise ignition timing: The ignition system must always have the correct ignition timing at the end of the compression stroke of the cylinders and an ignition advance angle consistent with changes in engine speed and load

Has enough durability: The ignition system must be reliable enough to withstand the effects of engine vibration and heat

2.3.3.1 Ignition system using contact breaker

This type of ignition system has the most basic structure In this type of ignition system, the primary current and ignition timing are controlled mechanically The primary current of the bobin is controlled to run intermittently through the contact of the fire screw The speed and vacuum centrifugal ignition advance regulator controls the ignition timing The distributor will distribute high voltage electricity from the secondary coil to the spark plugs

Contact breaker-type ignition systems are a simple and reliable way to ignite the air- fuel mixture in an engine They are often used in small engines, such as lawnmowers and chainsaws

A contact breaker-type ignition system consists of a flywheel, magneto, and spark plug The flywheel is a rotating disc with a magnet attached to it The magneto is a generator that produces electricity when the magnet passes by it The spark plug ignites the air-fuel mixture in the combustion chamber

To operate a screw-type ignition system, the flywheel must be rotated This can be done by pulling a starter cord or using an electric starter As the flywheel rotates, the magnet passes by the magneto, generating electricity This electricity is then used to create a spark at the spark plug, which ignites the air-fuel mixture in the combustion chamber

In this type of ignition system, the transistor controls the primary current, so that it flows intermittently in accordance with the electrical signals emitted from the signal generator The ignition advance angle is controlled mechanically as in a screw ignition system or can use position sensors such as optical or Hall types

There are two main types of semiconductor ignition systems: capacitive discharge (CDI) systems and inductive discharge (IDI) systems

A direct ignition system (DIS) is a type of ignition system that uses a separate ignition coil for each spark plug This eliminates the need for a distributor cap and rotor, which can be a source of failure in traditional ignition systems

Figure 2.9: Structure of Direct Ignition System

DIS systems are more complex than traditional ignition systems, but they offer a number of advantages:

• Improved performance: DIS systems can improve performance by providing a more consistent spark to each spark plug This can lead to better fuel economy and lower emissions

• Increased reliability: DIS systems are more reliable than traditional ignition systems because they have fewer moving parts

• Easier maintenance: DIS systems are easier to maintain than traditional ignition systems because there is no distributor cap and rotor to replace

An Electronic Spark Advance (ESA) system is a type of ignition system that uses a computer to calculate the optimal ignition timing for the engine This is in contrast to traditional ignition systems, which use a mechanical distributor to set the ignition timing

Figure 2.10: ESA Ignition System Diagram

In this type of ignition system, vacuum and centrifugal advance ignition is not used Instead, the ESA function of the Electronic Control Unit (ECU) controls the ignition advance angle.

Electronic fuel injection system

A fuel injector in CI (Compression ignition) engine and SI (Spark ignition) engine is a precisely controlled mechanical tool designed to deliver the correct quantity of fuel into

39 the engine, ensuring the creation of an ideal air-fuel mixture for efficient combustion This technology was initially developed in the early 20th century, primarily for diesel engines However, it gained widespread adoption in conventional gasoline engines during the latter part of the 20th century [10]

The basic functional requirements of the fuel injection system are:

Accurate metering of the fuel per each cycle: The quantity of fuel delivered to the engine must be precisely controlled to ensure optimal combustion and fuel efficiency 1

Accurate timing of the fuel injection: The timing of the fuel injection must be precise to ensure that the fuel is delivered at the right moment for optimal combustion

Proper atomization: The fuel must be atomized into a fine mist to ensure that it mixes evenly with air in the combustion chamber

Throttle body fuel injection (TBI) is a type of fuel injection system that uses a single fuel injector mounted in the throttle body to deliver fuel to all of the engine's cylinders TBI systems are relatively simple and inexpensive to produce, which made them popular for use in mass-produced vehicles in the 1980s and 1990s

2.2.3.2 Port or multi-point fuel injection

Multi-port fuel injection (MPFI), also known as port injection, is a type of fuel injection system that uses a separate fuel injector for each cylinder of the engine The injectors are located in the intake manifold, just before the intake valves This allows for more precise and efficient fuel delivery than throttle body fuel injection (TBI) systems MPFI has 2 typical types: Simultaneous MPFI system and Sequential MPFI system

Figure 2.12: Multi-port Fuel Injection

This type of fuel injection system injects fuel directly into the combustion chamber, bypassing the intake manifold entirely

Direct injection is a fuel delivery system that is common in modern cars with gas and diesel engines In this system, fuel is sprayed directly into the combustion chamber, bypassing the intake manifold entirely

Direct injection systems have several advantages over other types of fuel injection systems, including improved fuel efficiency, better performance, and reduced emissions However, these systems are more complex and expensive than other types of fuel injection systems

Direct fuel injection system, also known as gasoline direct injection (GDI), is a type of fuel injection system that injects fuel directly into the combustion chamber of each cylinder This is in contrast to port fuel injection (PFI) systems, which inject fuel into the intake manifold before the intake valves

Figure 2.13: Gasoline Direct Injection System

Sensor on system

Sensors are irreplaceable components of automotive electronic control systems Sensors are defined as “devices that transform (or transduce) physical quantities such as pressure or acceleration (called measurands) into output signals (usually electrical) that serve as inputs for control systems" In the primary years, sensors were defined as a device used to measure oil pressure, fuel level, coolant temperature, etc

In order to provide the correct amount of fuel for every operating condition, the engine control unit (ECU) has to monitor a huge number of input sensors

Sensors play a vital role in internal combustion engines (ICEs), providing essential information to the engine control unit (ECU) to ensure optimal performance, efficiency, and emissions Sensors must meet stringent requirements to withstand the harsh operating environment of an ICE, including extreme temperatures, pressures, and vibrations

Key requirements of sensors in ICEs:

• Accuracy: Sensors must provide accurate and reliable data to the ECU Even small errors in sensor readings can lead to significant performance and emissions penalties

• Response time: Sensors must respond quickly to changes in engine conditions This is especially important for sensors that monitor critical parameters such as knock and misfire, which can damage the engine if not detected and addressed promptly

• Durability: Sensors must be durable enough to withstand the harsh operating environment of an ICE This includes extreme temperatures (up to 1000°C), pressures (up to 200 bar), and vibrations (up to 100 kHz)

• Cost: Sensors must be cost-effective, especially for high-volume applications such as automotive engines

SENSORS OF TOYOTA VIOS 2022

Mass Airflow Meter

The Mass Air Flow Sensor (MAF) is located between the Air Filter and Throttle Body It is a vital component of the Engine Management System and measures the amount of air entering the engine and often includes the Intake Air Temperature Sensor (ATS) The Mass Air Flow Sensor signal (along with other sensor inputs) is used by the Engine Management ECU to determine correct Air/Fuel ratios, Ignition timing and on some vehicles transmission shifting [11]

The Mass Air Flow Sensor parameters include: Intake Air Temperature Measerement Resistor (Hot-Wire) and Heating Resistor (Hot-Wire)

Figure 3.1: Structure of MAF sensor

According to the repair manual book of Toyota, here is the location of mass air flow sensor on the engine:

Figure 3.2: Mass Air Flow Meter Position

The MAF sensor plays a crucial role in several aspects of vehicle performance:

• Fuel Efficiency: Accurate measurement of mass air flow rate ensures optimal fuel economy by maintaining the engine at the most efficient operating range

• Power Output: By supporting the correct air-fuel mixture, MAF sensors contribute to maximum power output and responsive acceleration

The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve The ECM uses this information to determine the fuel injection duration and to provide an appropriate air fuel ratio Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air By applying a specific electrical current to the wire, the ECM heats it to a specific temperature The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance To maintain a constant current value, the ECM varies the voltage applied to the wire and internal thermistor The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume [11]

The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit, and the power transistor is controlled so that the potentials of A and

B remain equal to maintain the predetermined temperature

Figure 3.3: Working of temperature sensor

Figure 3.4: Inside structure of temperature sensor

Figure 3.5: Wiring diagram of mass air flow meter

The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air When the intake air temperature is low, the resistance of the thermistor increases When the temperature is high, the resistance drops These variations in resistance are transmitted to the ECM as voltage changes

The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R Resistor R and the intake air temperature sensor are connected in series When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driving ability

• Decreased engine performance: This can manifest as sluggish acceleration, loss of power, or difficulty maintaining speed

• Rough idle: The engine may idle irregularly or stall altogether

• Increased fuel consumption: A faulty MAF sensor can lead to inaccurate fuel measurements, resulting in wasted fuel

• Check Engine Light: The illuminated Check Engine Light on your dashboard could indicate a MAF sensor issue, along with other potential problems

Specific symptoms for Toyota Vios:

• VSC (Vehicle Stability Control) and Traction Control warning lights: Some Vios owners have reported these lights activating due to faulty MAF sensor readings

• Jerky or hesitation during acceleration: This can be a sign of inaccurate air-fuel mixture caused by a malfunctioning MAF sensor

Quick MAF sensor diagnostic procedure without diagnosis machine:

Depending on the specific sensor issue, it is occasionally feasible to do a rapid diagnosis of the MAF sensor without the need for any test equipment Engine issues can be recognized by having trouble with poor idle, a no-start scenario, or sporadic performance concerns

If the vehicle has been experiencing intermittent faults or poor idle problems:

Step 1: Engage the parking brake

Step 2: Set the transmission to Park (automatic) or Neutral (manual)

Step 3: Start the engine and let it idle

Step 4: Pop the hood open

Step 5: Lightly tap the MAF sensor and electrical connector with a screwdriver handle Wiggle the wires as well

Result: If the engine stalls, idle is upset, or idle gets better, the MAF sensor is likely defective

MAF sensor diagnosis with diagnosis machine:

After troubleshooting the problem and isolating the area, technician connect the diagnosis machine to the communicated gate via OBD There could be the trouble codes can display on the diagnosis machine for the technicians to know the issues that occurs on the mass air flow sensor:

Table 3.1 System failure diagnosed codes and inspection area

DTC No Detection Item Trouble Area

Circuit Low ã Open or short in mass air flow meter circuit ã Mass air flow meter ã ECM

Circuit High ã Open or short in mass air flow meter circuit ã Mass air flow meter ã ECM

Table 3.2: Compared value for system malfunction

Approximately 0.0 ã Open in mass air flow meter power source circuit ã Open or short in VG circuit 271.0 or more ã Open in E2G circuit

How to test a mass air flow sensor?

Testing the mass air flow sensor’s power feed:

Step 1: Pop the hood open

Step 2: Unplug the MAF sensor electrical connector

Step 3: Set the VOM to 20 volts DC or auto range

Step 4: Connect the meter’s red lead to the B25-3 (+B) terminal on the harness connector (the one leading to the computer)

Step 5: Connect the meter’s black lead to the ground (-) pin on the sensor connector Step 6: Turn the ignition switch to the On position, but do not start the engine

Step 7: Value should be around 11 to 14 volts or pretty close to battery voltage; otherwise, there’s a problem in the power side of the circuit of the sensor

Figure 3.6: Front view of wire harness connector (to Mass Air Flow Meter)

Result : If the power feed to sensor is adequate (5V), then check the sensor

Testing the mass air flow sensor voltage signal:

Step 1: Turn the ignition switch to the Off position

Step 2: Plug in the MAF sensor’s electrical connector

Step 3: Back-probe the sensor’s signal (+) wire with the meter’s red lead, and the ground (-) wire with the meter’s black lead

Step 4: Make sure the meter’s leads are away from moving engine components

Step 5: Engage the parking brake and set the transmission to Park (automatic) or Neutral (manual)

Step 6: Start the engine and let it idle

Step 7: The meter should register 0.5 to 0.7 volts

Step 8: Lightly tap the MAF sensor and electrical connector with the handle of a screwdriver or wrench Then, wiggle the wires Voltage output should remain steady

Result: If it fluctuates or the engine misfires or surges, there could be loose electrical connections inside the sensor and needs to be replaced

Step 9: Increase engine speed between 2500 and 3500 rpm

Step 10: The sensor’s output signal should increase smoothly between 1.5 and 3.0 volts

If the reading becomes erratic or output voltage seems slow, the hot-wire or sensing element may be dirty or contaminated If dirt or contamination is the problem, this may suggest a bad self-cleaning circuit or relay

If there is no output response from the sensor, replace the mass air flow sensor

Figure 3.7: Wiring diagrams of hot wire inside MAF

Testing the MAF Sensor’s Hot Wire:

Step 1: Turn the ignition switch to the Off position

Step 2: Unplug the MAF sensor electrical connector

Step 3: Set the VOM to the Ohms scale

Step 4: Connect the meter leads to the signal (+) and ground (-) pins on the sensor connector

Step 5: If the hot wire of the sensor is damaged, the meter will register infinite resistance

Table 3.4: MAF Sensor Test Value

MAF ã Engine not running ã 30 seconds after ignition switch turned to ON

Engine Coolant Temperature Sensor

The engine coolant temperature sensor is temperature-variable resistor, which usually has a negative temperature coefficient It is a two-wire thermistor immersed in coolant and measures its temperature The onboard computer uses the signal of ECT as the main correction factor when calculating the ignition advance and the injection duration [13]

Figure 3.8: Structure of ECT sensor

The ECT sensor plays a vital role in several engine functions:

• Fuel Injection: The ECM uses the ECT sensor data to determine the appropriate amount of fuel to inject into the engine When the engine is cold, the ECM enriches the fuel mixture to aid in starting and warming up the engine As the engine reaches operating temperature, the ECM lean out the fuel mixture for optimal efficiency

• Ignition Timing: The ECM also uses the ECT sensor data to adjust the ignition timing When the engine is cold, the ECM retards the ignition timing to prevent knocking

As the engine warms up, the ECM advances the ignition timing for maximum power and efficiency

• Fan Operation: The ECM controls the operation of the electric cooling fan based on the ECT sensor data When the engine temperature rises, the ECM activates the fan to draw air through the radiator, helping to cool the coolant and prevent overheating

Figure 3.9: Position of Engine Coolant Temperature Sensor

A coolant temperature sensor (CTS) (also known as an ECT sensor or ECTS (engine coolant temperature sensor) is used to measure the temperature of the coolant/antifreeze mix in the cooling system, which indicates how much heat the engine is producing [12]

To get an accurate reading of the current engine temperature, the ECU sends a regulated voltage to the CTS via pin 22 to the pin 2 on the sensor The resistance of the sensor varies with the temperature, this is how the ECU can monitor temperature changes

Figure 3.10: Wiring Diagram of Engine Coolant Temperature Sensor

The ECU uses this reading to calculate the coolant temperature, and from there adjusts the fuel injection, fuel mix, and ignition timing, and controls when the electric cooling fan is switched on and off This information is also used to send an accurate reading of the engine temperature to a gauge on the dashboard [12]

A faulty ECT sensor can lead to various engine problems, including:

• Overheating: If the ECT sensor is reading lower than the actual coolant temperature, the ECM may not activate the cooling fan properly, leading to engine overheating

• Rough Idle: If the ECT sensor is reading higher than the actual coolant temperature, the ECM may enrich the fuel mixture excessively, causing a rough idle or stalling

• Check Engine Light: A faulty ECT sensor may trigger the check engine light, indicating a problem with the engine management system

Table 3.7: Engine coolant temperature sensor inspection with diagnosis device

DTC No Detection Item Trouble Area

Malfunction ã Open or short in engine coolant temperature sensor circuit ã Engine coolant temperature sensor ã ECM

Input ã Short in engine coolant temperature sensor circuit ã Engine coolant temperature sensor ã ECM

Input ã Open in engine coolant temperature sensor circuit ã Engine coolant temperature sensor ã ECM

Engine coolant temperature sensor inspect using multi-meter:

Power feed to sensor testing:

Step 1: Remove the cables connected to the sensor

Step 2: Push the Start/Stop engine button once

Step 3: Connect the red line of the multi-meter to terminal two and ground it with the black one

Result: A value of up to 5 volts indicates that there is no problem on this end

Sensor continuity testing by using multi-meter:

Step 1: Disconnect the B18 engine coolant temperature sensor connector

Step 2: Measure the resistance and write it down by attaching the multi-meter to the sensor’s terminals

Step 3: Let the engine run for around two minutes and then shut it off again

Step 4: Compare this reading to the one from a cold engine

Result: The difference should be at least 200 ohms If this is not the case, the sensor is not working properly

Tester Connection Condition Specified Condition

B18-2 - B47-22 (THW) Always Below 1 Ω B18-1 - B47-30 (ETHW) Always Below 1 Ω

Check sensor voltage testing by using multi-meter:

Step 1: Proceed as with the continuity testing and attach it to the sensor while the engine is off

Step 2: Write down the voltage

Step 3: The value is usually around 5 volts

Figure 3.11: Front-view of ECT sensor connector

Step 4: Reconnect the sensor and run the engine for about two minutes before turning it off

Step 5: Disconnect everything and measure the voltage again

Result: It should be down to as low as 0.25 volts after the motor warms up No change in voltage indicates a faulty coolant sensor

The engine coolant temperature sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant When the coolant temperature is low, the resistance in the thermistor increases When the temperature is high, the resistance drops These variations in resistance are reflected in the output voltage from the sensor The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature sensor circuit and stores a DTC

If the sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the engine coolant temperature sensor circuit, and stores DTC P0118 Conversely, if the voltage output is less than 0.14 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and stores DTC P0117.

Acceleration Pedal Position Sensor

The Acceleration Pedal Position Sensor (APPS) is a crucial component of the Toyota Vios electronic throttle control (ETC) system It plays a vital role in determining the driver's intention to accelerate and translates that input into an electronic signal that controls the engine's throttle opening This precise control of the throttle opening is essential for ensuring smooth, responsive acceleration, fuel efficiency, and emission reduction [13]

The primary purpose of the APPS is to accurately measure the position of the accelerator pedal and convey this information to the engine control module (ECM) The ECM, in turn, utilizes this data to calculate the desired engine speed and adjusts the throttle opening accordingly

Figure 3.12: Acceleration Pedal Sensor Position

This precise control of the throttle opening ensures that the engine responds accurately to the driver's input, providing a smooth and controlled acceleration experience

A non-contact type accelerator pedal sensor assembly is used

The accelerator pedal sensor transmits the position of the accelerator pedal to the engine control unit Based on this information, the load requested by the driver can be implemented immediately

Figure 3.13: When Acceleration Pedal is depressed and released

This sensor uses a Hall IC, which can retrieve the strength of the magnetic field as an electrical signal, using the Hall effect, in which the output voltage can be directly received in accordance with the accelerator pedal depression amount When the accelerator pedal depression amount changes, the angle of the magnetic field towards the flow of the current in the Hall IC changes As a result, the strength of the current and vertical magnetic field changes Due to this, the change in the voltage generated in the vertical direction towards the forced current and direction of the magnetic field is sent to the ECM as an accelerator pedal depression amount signal Also, in order to ensure reliability, duplicate sensors (main and sub) with differing sensor output characteristics, are used

A faulty APPS can lead to various problems, including:

• Erratic engine speed: The engine speed may fluctuate erratically or respond inconsistently to pedal input

• Hesitation or surging: The engine may hesitate or surge during acceleration, causing an uncomfortable driving experience

• Limp mode: In severe cases, the ECM may activate limp mode, limiting the engine's power output to protect against further damage

• Check engine light: A faulty APPS may trigger the check engine light, indicating a problem with the engine management system

Accelerator pedal sensor testing by diagnosis device:

Step 1: Connect the GTS to the DLC3

Step 2: Turn the ignition switch to ON

Step 3: Turn the diagnosis device ON

Step 4: Read the values displayed on the diagnosis device

Result: If the result is not as specified, check the accelerator pedal sensor assembly, wire harness or ECM

Accelerator pedal position sensor signal voltage testing using multi-meter:

Step 2: Connect the red probe of the multi-meter to pin A13-3 (VPA2)/ pin A13-6 (VPA1) (output signal pin) of the sensor

Step 3: Connect the black probe of the multi-meter to pin A13-2 (EP2)/ pin A13-5 (EP1) of the sensor

Figure 3.14: Front-view of APPS connector

Step 4: Observe the multi-meter value display while pressing and releasing the accelerator pedal

Result: A properly functioning sensor will show a gradual increase or decrease in voltage or resistance as you press and release the pedal If the readings are erratic or there is no change, the sensor may be faulty

Tester Display Condition Specified Condition

Accelerator pedal is released 0.5 to 1.1 V

Accelerator pedal is fully depressed 2.5 to 4.5 V

Accelerator pedal is released 1.2 to 2.0 V Accelerator pedal is fully depressed 3.4 to 4.7 V

Throttle Position Sensor

The throttle position sensor (TPS) is a crucial component of the Toyota Vios engine management system It monitors the position of the throttle valve, which controls the amount of air entering the engine This information is essential for the engine control module (ECM) to determine the desired fuel injection rate and ignition timing The correct fuel injection rate and ignition timing are important for engine efficiency, power output, and emissions control

The primary purpose of the TPS is to accurately measure the angle of the throttle valve and transmit this information to the ECM The ECM, in turn, utilizes this data to calculate the desired air intake and adjust the fuel injection rate and ignition timing accordingly This precise control of the fuel mixture and ignition timing ensures that the engine operates efficiently, produces the maximum amount of power, and meets emission standards

Table 3.10: Table of Components on Throttle Body

*1 Air cleaner hose assembly *2 No 1 air hose

*3 No 1 engine cover *4 No 2 ventilation hose

*5 No 2 water by-pass hose *6 No 3 water by-pass hose

*7 Throttle body gasket *8 Throttle body with motor assembly

*9 Ventilation hose *10 Wire harness clamp bracket

The TPS plays a critical role in several aspects of vehicle performance:

• Fuel Efficiency: Accurate measurement of throttle position ensures optimal fuel economy by maintaining the engine at the most efficient operating range

• Engine Protection: The TPS prevents engine damage from sudden and excessive throttle inputs by limiting fuel injection and retarding ignition timing

• Power Output: Precise control of the fuel mixture and ignition timing maximizes power output, providing a responsive and enjoyable driving experience

• Emission Reduction: By optimizing fuel combustion and reducing unnecessary engine load, the TPS contributes to lower emissions

• Engine Protection: The TPS prevents engine damage from sudden and excessive throttle inputs by limiting fuel injection and retarding ignition timing

The throttle position sensor is mounted on the throttle body with motor assembly and detects the opening angle of the throttle valve This sensor is a non-contact type sensor It uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds A non-contact type throttle position is used [13]

This sensor uses a Hall IC, which can retrieve the strength of the magnetic field as an electrical signal using Hall effect, in which the output voltage can be directly received in accordance with the throttle valve opening angle When the throttle valve opening angle changes, the angle of the magnetic field towards the flow of the current in the Hall IC changes As a result, the strength of the current and vertical magnetic field changes Due to this, the change in the voltage generated in the vertical direction towards the current and direction of the magnetic field is sent to the ECM as a throttle valve opening angle signal Also, duplicate sensors (main and sub) with differing sensor output characteristics, are used, ensuring reliability [12]

Figure 3.16: Wiring Diagram of TPS Figure 3.17: Sensor Output Voltage with

The electronic throttle control system is composed of the throttle actuator, throttle position sensor, accelerator pedal position sensor, and ECM The ECM operates the throttle actuator to regulate the throttle valve in response to driver inputs The throttle position sensor detects the opening angle of the throttle valve, and provides the ECM with feedback so that the throttle valve can be appropriately controlled by the ECM [12]

The throttle position sensor has 2 sensor circuits, VTA1 and VTA2 each of which transmits a signal VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA1 The sensor signal voltages vary between 0 V and 5 V in

62 proportion to the throttle valve opening angle, and are transmitted to the VTA1 and VTA2 terminals of the ECM [12]

As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control [12]

Figure 3.18: Output Characteristics of sensor

Here are five important symptoms of a problematic throttle position sensor:

• Lack of power: When the throttle valve position or throttle angle is not reported correctly, more air may enter the fuel mixture than the ECU compensates for which then produces a lack of power for the engine The opposite can also happen due to malfunctioning a TPS, where your vehicle surges forward when you don’t plan to This leads to overall decreased engine performance and other car issues

• Trouble accelerating the car: Since a faulty throttle position sensor can cause reduced engine power, your car may face some trouble during acceleration The car may experience uneven acceleration, or it will not accelerate after a certain point This issue may ultimately affect the engine life and lead to poor fuel economy

• Increased fuel consumption: A dirty throttle sensor may send false readings to the ECU and cause your engine to consume more fuel than it should, severely decreasing your car’s fuel efficiency This is similar to when debris collects around the throttle opening (the

63 throttle plate or the throttle valve), stopping airflow into the engine, and causing issues with unburned fuel passing through the exhaust system

• Uneven idle: When the throttle plate operation isn’t reported effectively by the TPS, one of the tell-tale signs is poor or low idling This includes the engine stalling and coming to a stop, a low idle after starting, or stalling when the accelerator pedal is pressed Dirt collected around the throttle can also contribute to a fluctuating idle speed

• Illuminated check engine light: The TPS sensor is primarily responsible for monitoring the throttle plate (which controls the amount of air entering the engine) If your car has a loose TPS connector (wire) or the throttle sensor fails to monitor throttle functioning properly, it will affect the engine performance, and the engine will trigger the check engine light in response

The ECM determines the actual opening angle of the throttle valve from the throttle position sensor signal The actual opening angle is compared to the target opening angle commanded by the ECM If the difference between these two values is outside the standard range, the ECM interprets this as a malfunction in the electronic throttle control system The ECM then illuminates the MIL and stores the DTC [12]

Table 3.11: Diagnosis code and inspection area of throttle position sensor

No Detection Item Trouble Area

Sensor / Switch "A" Circuit ã Throttle position sensor (throttle body with motor assembly) ã ECM

Range / Performance ã Throttle position sensor (throttle body with motor assembly) ã Throttle position sensor circuit ã ECM

Low Input ã Throttle position sensor (throttle body with motor assembly)

No Detection Item Trouble Area ã Short in VTA1 circuit ã Open in VCTA circuit ã ECM

High Input ã Throttle position sensor (throttle body with motor assembly) ã Open in VTA1 circuit ã Open in ETA circuit ã Short between VCTA and VTA1 circuits ã ECM

Sensor / Switch "B" Circuit ã Throttle position sensor (throttle body with motor assembly) ã ECM

Low Input ã Throttle position sensor (throttle body with motor assembly) ã Short in VTA2 circuit ã Open in VCTA circuit ã ECM

High Input ã Throttle position sensor (throttle body with motor assembly) ã Open in VTA2 circuit ã Short between VCTA and VTA2 circuits ã ECM

Voltage Correlation ã Short between VTA1 and VTA2 circuits ã Open in ETA circuit ã Throttle position sensor (throttle body with motor assembly) ã ECM

Check throttle body with motor assembly:

Step 1: Start the engine and check that the MIL is not illuminated

Step 2: After the engine is warmed up, check that the idle speed is within the specified range with the A/C switch off (w/ air conditioning system)

Continuously Variable Transaxle 680 to 780 rpm

Step 3: Perform a road test and confirm that there are no abnormalities

Check the throttle position sensor

Step 1: Connect the diagnosis device to the DLC3

Step 2: Turn the ignition switch to ON

Step 3: Turn the GTS on

Step 4: Enter the following menus: Powertrain / Engine and ECT / Data List / Throttle Position No 1 and Throttle Position No 2

Step 5: Depress the accelerator pedal When the throttle valve is fully open, check that the value of Throttle Sensor Position is as specified

Result: If the percentage is less than 60%, replace the throttle body with motor assembly

Table 3.13 Voltage reference (normal working condition)

Throttle Position No.1 0.5 to 1.1 V 3.2 to 4.8 V Throttle Position No.2 2.1 to 3.1 V 4.6 to 4.98 V

Check harness and connector (ECM – Throttle body with motor assembly)

Step 1: Disconnect the B46 ECM connector

Step 2: Disconnect the B17 throttle body with motor assembly connector

Step 3: Measure the resistance according to the value(s) in the table below

Table 3.14 Standard Resistance of Connectors Continuity

Tester connection Condition Specified condition

B46-29 (VCTA) - B17-5 (VC) Always Below 1 Ω B46-30 (VTA1) -B17-6 (VTA) Always Below 1 Ω

Body ground and other terminals Always 10 kΩ or higher

Body ground and other terminals Always 10 kΩ or higher

- Body ground and other terminals Always 10 kΩ or higher

Inspect throttle body with assembly

Check the resistance, measure the resistance according to the value in the table below

Table 3.15 Throttle Position Sensor Standard Resistance:

Tester Connection Condition Specified Condition

M+ and M- are two poles of motor assembly in Throttle Position Sensor

Result: If the result is not as specified, replace the throttle body with motor assembly

Check terminal voltage (power feed of throttle position sensor with motor assembly)

Figure 3.19: Front view of wire harness connector (to Throttle Body with Motor

Step 1: Disconnect the throttle body with motor assembly connector

Step 2: Turn the ignition switch to ON

Step 3: Measure the voltage according to the value(s) in the table below

Tester Connection Switch Condition Specified Condition

B17-5 (VC) - B17-3 (E2) Ignition switch ON 4.5 to 5.5 V

Check throttle position sensor signal voltage

Step 1: Place the black probe on the pin E2 of the sensor, red probe on the signal voltage pin (VTA1, VTA2)

Step 2: Slowly change the angle of throttle plate by pressing and depressing gas pedal

Step 3: Consider the value on the multi-meter

With the throttle plate fully closed, the multi-meter is expected to read between 0.2V to 1.5V if the throttle position sensor is in good condition

When the plate is fully open, the multi-meter is also expected to display 5 volts (or 3.5 volts in some TPS models)

Knock Sensor

What is knock phenomenon in engine?

The phenomenon of knock is when the spark plug turns on an electric spark to start the combustion process, creating a spark that spreads in all directions inside the combustion chamber, from the point between the two spark plug electrodes, increasing the temperature and pressure inside the combustion chamber quickly [14]

At the same time, one or several other sparks may also appear at different points in the combustion chamber, and spread parallel to the fire film created by the spark plug

When these sparks collide with each other, high-frequency shock waves are created, causing the pressure in the combustion chamber to suddenly increase On the other hand, when these shock waves resonate with each other, they will create shock waves with extremely high frequencies

Figure 3.20: Knock occurs inside Cylinder

As a result, these shock waves create metallic knocking sounds appearing in the engine At the same time, the temperature inside the engine increases suddenly

The cause may originate from the temperature of the combustion chamber being too high, causing part of the air mixture to burn before the spark plug ignites

This combustion process will create a large amount of pressure, and collide with the amount of pressure created by the spark plug burning the fuel mixture This creates extensive vibrations that impact the cylinder walls, leading to damage to engine parts such as pistons

Knock sensors act as sentinels for the engine, constantly monitoring combustion patterns and detecting the presence of knocking They serve as a feedback mechanism, providing real-time information to the ECM about the engine's combustion stability Upon detecting knocking, the knock sensors send signals to the ECM, triggering an immediate adjustment in ignition timing

A flat type knock sensor (non-resonant type) has a structure that can detect vibrations between approximately 5 kHz and 15 kHz

The knock sensor is fitted onto the engine block to detect engine knocking

The knock sensor contains a piezoelectric element which generates a voltage when it becomes deformed

The voltage is generated when the engine block vibrates due to knocking Any occurrence of engine knocking can be suppressed by delaying the ignition timing

In the Toyota Vios 2022, knock sensors are located in the engine block, below the intake manifold, near the oil filter

In a conventional knock control sensor (resonant type), a vibration plate is built into the sensor This plate has the same resonance point as the knocking frequency of the engine block This sensor can only detect vibration in this frequency band

A flat type knock control sensor (non-resonant type) has the ability to detect vibration in a wider frequency band (from about 5 kHz to 15 kHz) It has the following features The engine knocking frequency will vary slightly depending on the engine speed The flat type knock control sensor can detect vibration even when the engine knocking

70 frequency changes Due to the use of the flat type knock control sensor, the vibration detection ability is increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible

Figure 3.21: Knock Sensor Flat-type

Figure 3.23: Flat type Knock Sensor Elements

When the engine is running, for some reason there is a knocking sound (self- knocking, engine overheating, mechanical impact, etc.) the sensor will create a voltage signal sent to the ECU and the ECU will regulate the engine Adjust the ignition delay to reduce the knocking sound

Specifically: The piezoelectric elements of the detonation sensor are designed to have a size with a natural frequency that coincides with the vibration frequency of the engine when detonation occurs so that a resonance effect occurs (f = 6KHz - 13KHz) [12]

Thus, when the engine detonates, the quartz crystal will experience the greatest pressure and generate a voltage This voltage signal has a value of less than 2.5V Thanks to this signal, the engine ECU recognizes the phenomenon of detonation and adjusts to reduce the ignition angle until detonation no longer occurs The engine ECU can adjust the ignition timing again [12]

Figure 3.24: Wiring diagram of Knock sensor

A faulty knock sensor can lead to several problems, including:

• Engine Damage: Knocking can cause severe engine damage, including piston ring failure, valve breakage, and cylinder wall scoring Without knock sensors to detect and prevent knocking, this damage can occur more easily

• Reduced Power: Knocking can reduce engine power output as the engine tries to protect itself from damage If the knock sensors are not functioning properly, the engine may not be able to produce its full power

• Check Engine Light: A faulty knock sensor may trigger the check engine light, indicating a problem with the engine management system This light is a warning that something is wrong with the engine and should be checked by a qualified mechanic

• Erratic Fuel Economy: Knocking can affect fuel economy as the engine tries to adjust the air-fuel mixture to prevent further knocking If the knock sensors are not working properly, the engine may not be able to optimize fuel efficiency

Air Fuel Ratio Sensor

Heated oxygen sensors (HO2S), also known as O2 sensors, are crucial components of the Toyota Vios 2022's engine management system They play a vital role in maintaining optimal fuel efficiency and reducing emissions by providing accurate feedback on the oxygen content in the exhaust gases This information is used by the engine control module (ECM) to adjust the air-fuel mixture, ensuring that the engine operates at the stoichiometric ratio, which is the ideal ratio of air to fuel for complete combustion [15]

The primary purpose of heated oxygen sensors is to accurately measure the oxygen content in the exhaust gases and transmit this information to the ECM The ECM analyzes this data and determines the air-fuel mixture ratio If the mixture is too rich (too much fuel), the ECM reduces fuel injection If the mixture is too lean (too little fuel), the ECM increases fuel injection This closed-loop control system ensures that the engine operates at the stoichiometric ratio, maximizing fuel efficiency and minimizing emissions

In the Toyota Vios 2022, heated oxygen sensors are typically located in the exhaust manifold, close to the engine This placement ensures that the sensors measure the oxygen content in the exhaust gases before they are diluted by the atmosphere

Figure 3.27: Heated Oxygen Sensor Position

A typical heated oxygen sensor consists of several key components:

• Zirconia element: The heart of the sensor is a zirconia element, a ceramic material that exhibits high electrical conductivity when hot and allows oxygen ions to move through it

• Protective housing: The zirconia element is encased in a protective housing that shields it from the harsh environment of the exhaust system

• Electrodes: Two electrodes are placed in contact with the zirconia element, one on each side, to measure the voltage difference between them

• Heater: The sensor is equipped with a heater that quickly brings it up to operating temperature, ensuring accurate readings even during cold starts

*1 Air Fuel Ratio Sensor *5 Heater

Figure 3.29: Toyota Vios 2022 Heated Oxygen Sensor

The oxygen sensor and the air fuel ratio sensor differ in output characteristics

The output voltage of the oxygen sensor changes in accordance with the oxygen concentration in the exhaust gas The ECM uses this output voltage to determine whether the present air fuel ratio is richer or leaner than the stoichiometric air fuel ratio

Approximately 0.4 V is constantly applied to the air fuel ratio sensor, which outputs an amperage that varies in accordance with the oxygen concentration in the exhaust gas The ECM converts the changes in the output amperage into voltage in order to linearly detect the present air fuel ratio [12]

The basic construction of the oxygen sensor and the air fuel ratio sensor is the same However, they are divided into the cup type and the planar type, according to the different types of heater construction that are used

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) is used For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used [12]

The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect the oxygen concentration in the exhaust gas If the zirconia element is at the appropriate temperature, and the difference between the oxygen concentrations surrounding the inside and outside surfaces of the sensor is large, the zirconia element generates voltage signals In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor

Figure 3.30: Structure and Working of Heated Oxygen Sensor

The heated oxygen sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low)

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e less than 0.21 V) [12]

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is low The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e more than 0.69 V) The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level

Heated Oxygen Sensors are heated to ensure that they reach operating temperature quickly This is important because Heated Oxygen Sensors only generate an accurate signal when they are hot

The HO2S sensor circuit is powered by a 12-volt battery The heater is powered by the battery through a relay The relay is controlled by the ECU The control signal from ECU will generate a current through the coil and turn on the relay when the engine is started This activates the heater and begins to heat the HO2S sensor

Figure 3.31: Heated Oxygen Sensor Wiring Diagram

The signal circuit is a high-impedance circuit This means that it has a high resistance This is necessary to protect the HO2S sensor from damage

The ground circuit is a low-impedance circuit This means that it has a low resistance This is necessary to ensure that the HO2S sensor and the heater have a good electrical ground

The ECU uses the signal from the HO2S sensor to adjust the air-fuel mixture If the ECU detects that the exhaust gas is rich in oxygen, it will lean out the air-fuel mixture If the ECU detects that the exhaust gas is poor in oxygen, it will enrich the air-fuel mixture

By adjusting the air-fuel mixture, the ECU can ensure that the engine burns fuel efficiently and produces minimal emissions

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control

A faulty heated oxygen sensor can lead to several problems, including:

Crankshaft Position Sensor

The crankshaft position sensor (CKP), also known as the crank sensor, is a crucial component of the Toyota Vios 2022's engine management system It plays a vital role in ensuring accurate ignition timing and engine synchronization The CKP sensor monitors the rotational position of the crankshaft, which converts the reciprocating motion of the pistons into rotational motion This information is essential for the engine control module (ECM) to determine the exact timing of the spark plugs and fuel injectors, ensuring that the engine's combustion cycles occur at the precise moment for optimal power and efficiency

The CKP sensor is typically located near the crankshaft pulley or flywheel, allowing it to detect the crankshaft's rotational position directly It is a compact electronic device that consists of a pickup coil, a circuit board, and a connector The pickup coil is the key component that generates an electrical signal based on the proximity and movement of a metal target, typically a toothed recluctor wheel or a magnetic ring attached to the crankshaft

Figure 3.35: Crankshaft position sensor position

Figure 3.36: Toyota Vios 2022 Crankshaft position sensor

The CKP sensor plays a critical role in several aspects of engine performance:

• Ignition Timing: Accurate crankshaft position information is essential for precise ignition timing The ECM uses the CKP sensor signal to calculate the exact moment when to trigger the spark plugs, ensuring that the spark occurs at the optimal point in the combustion cycle for maximum power and efficiency

• Engine Synchronization: The CKP sensor synchronizes the engine's various components, such as the fuel injection system and camshaft position sensor, ensuring that they operate together in harmony This synchronization is crucial for smooth engine operation and optimal performance

• Engine Protection: Proper CKP sensor operation helps protect the engine from damage caused by misfires or incorrect ignition timing If the CKP sensor is faulty, it can lead to engine knock, misfires, and reduced power

• Diagnostic Tool: The CKP sensor signal is also used by the ECM for diagnostic purposes The ECM monitors the CKP sensor signal to detect any irregularities that may indicate an engine problem

Crankshaft position sensor used Magnetic Resistance Element (MRE)

Figure 3.37: Working of Crankshaft position sensor

The timing rotor of the crankshaft has 34 teeth, with 2 teeth missing Based on these teeth, the crank position sensor transmits crank position signals (NE signal) consisting of

33 high or low output pulses every 10° per revolution of the crankshaft The ECM uses the

NE signal for detecting the crank position as well as for detecting the engine speed It uses the missing teeth signal for determining the top dead center [16]

Figure 3.39: Wiring Diagram of Crankshaft sensor

A faulty CKP sensor can lead to various problems, including:

• Hard Starting or Stalling: The engine may experience difficulty starting or stall frequently due to incorrect injection timing and engine synchronization issues

• Reduced Power or Erratic Idle: The engine may lack power or feel sluggish during acceleration It may also idle erratically or stall, especially when cold

• Check Engine Light: A faulty CKP sensor can trigger the check engine light, indicating a problem with the engine management system

• Engine Knock or Misfires: Incorrect ignition timing caused by a faulty CKP sensor can lead to engine knock, a harsh pinging or rattling sound, and misfires, which are irregular combustion events in the engine cylinders

Table 3.25: Crankshaft position sensor inspection with diagnosis device

No Detection Item Trouble Area

"A" Circuit ã Open or short in crankshaft position sensor circuit ã Crankshaft position sensor ã Crankshaft (crankshaft angle sensor plate) ã ECM

"A" Circuit Low Input ã Open or short in crankshaft position sensor circuit ã Crankshaft position sensor ã ECM

"A" Circuit High Input ã Open or short in crankshaft position sensor circuit ã Crankshaft position sensor ã ECM

"A" Circuit Intermittent ã Open or short in crankshaft position sensor circuit ã Crankshaft position sensor ã Crankshaft (crankshaft angle sensor plate) ã ECM

Checking voltage (power source of crankshaft position sensor)

Step 1: Disconnect the crankshaft position sensor connector

Step 2: Turn the ignition switch to ON

Step 3: Measure the Voltage according to the value in the table below:

Figure 3.40: Front view of wire harness connector (to Crankshaft Position Sensor)

Table 3.26: Standard voltage of power source of crankshaft position sensor

Tester Connection Switch Condition Specified Condition

B35-3 (VC) - Body ground Ignition switch ON 4.5 to 5.5 V

Step 1: Disconnect the B35 crankshaft position sensor connector

Step 2: Disconnect the B46 ECM connector

Step 3: Measure the Resistance according to the value in the table below:

Table 3.27: Standard voltage of power source of crankshaft position sensor

Tester Connection Condition Specified Condition

B35-1 (NE+) - B46-27 (NE+) Always Below 1 Ω B35-2 (NE-) - B46-34 (NE-) Always Below 1 Ω B35-1 (NE+) or B46-27 (NE+) -

Body ground and other terminals Always 10 kΩ or higher

B35-2 (NE-) or B46-34 (NE-) - Body ground and other terminals Always 10 kΩ or higher

Check the crankshaft position sensor installation condition an Inspecting crankshaft

Check the teeth of the crankshaft angle sensor plate OK means crankshaft angle sensor plate does not have any cranks or deformation

If it is not OK, replace a new crankshaft angle sensor plate.

Camshaft Position Sensor

The Camshaft position sensor (CMP), also known as the cam sensor, is a vital component of the Toyota Vios 2022's engine management system It plays a critical role in ensuring accurate valve timing and engine synchronization The CMP sensor monitors the rotational position of the camshaft, which controls the opening and closing of the intake and exhaust valves This information is essential for the engine control module (ECM) to precisely determine the timing of the fuel injection and ignition events, ensuring that the engine operates efficiently and produces maximum power

The CMP sensor is typically located near the camshaft sprocket or camshaft cover, allowing it to detect the camshaft's rotational position directly It is a compact electronic device that consists of a pickup coil, a circuit board, and a connector The pickup coil is the key component that generates an electrical signal based on the proximity and movement of a metal target, typically a toothed reluctor wheel or a magnetic ring attached to the camshaft

Figure 3.42: Toyota Vios 2022 Camshaft position sensor Figure 3.43: Camshaft Position Sensor

The CMP sensor plays a crucial role in several aspects of engine performance:

• Valve Timing: Accurate camshaft position information is essential for precise valve timing The ECM uses the CMP sensor signal to calculate the exact moment when to activate the fuel injectors and spark plugs, ensuring that the valves are open and closed at the optimal points in the combustion cycle for maximum power and efficiency

• Engine Synchronization: The CMP sensor synchronizes the engine's various components, such as the crankshaft position sensor and ignition system, ensuring that they operate together in harmony This synchronization is crucial for smooth engine operation and optimal performance

• Emission Reduction: Proper CMP sensor operation helps reduce emissions by ensuring that the engine operates efficiently and burns fuel completely Incorrect valve timing can lead to incomplete combustion, producing harmful pollutants

• Engine Protection: Proper CMP sensor operation helps protect the engine from damage caused by misfires or incorrect valve timing If the CMP sensor is faulty, it can lead to misfires, engine knock, and reduced power

• Engine Synchronization: The CMP sensor synchronizes the engine's various components, such as the crankshaft position sensor and ignition system, ensuring that they operate together in harmony This synchronization is crucial for smooth engine operation and optimal performance

An MRE type sensor consists of an MRE, a magnet and a sensor The direction of the magnetic field changes due to the profile (protruding and non-protruding portions) of the timing rotor, which passes by the sensor As a result, the resistance of the MRE changes, and the output voltage to the ECM changes to either high or low The ECM detects cam position based on this output voltage

The camshaft has a timing rotor for the camshaft position sensor When the camshaft rotates, changes occur in the air gaps between the timing rotor and MRE, which affects the magnetic field

Figure 3.44: Working Principle of MRE type sensor

Figure 3.45: Inspection using an oscilloscope

ECM Terminal Name CH1: Between VV1+ and VV1-

CH2: Between EV1+ and EV1- Tester Range 5 V/DIV., 20 ms./DIV

Condition Idling with warm engine

The camshaft position sensor for the intake camshaft (VV1 signal) consists of a magnet and MRE (Magneto Resistance Element)

The camshaft has a timing rotor for the camshaft position sensor When the camshaft rotates, changes occur in the air gaps between the timing rotor and MRE, which affects the magnetic field As a result, the resistance of the MRE material fluctuates The camshaft position sensor converts the camshaft rotation data to pulse signals, uses the pulse signals to determine the camshaft angle, and sends it to the ECM Then the ECM uses this data to control fuel injection duration and injection timing [12]

Figure 3.46: Wiring Diagram of Camshaft position sensor

A faulty CMP sensor can lead to various problems, including:

• Hard Starting or Stalling: The engine may experience difficulty starting or stall frequently due to incorrect valve timing and engine synchronization issues

• Reduced Power or Erratic Idle: The engine may lack power or feel sluggish during acceleration It may also idle erratically or stall, especially when cold

• Check Engine Light: A faulty CMP sensor can trigger the check engine light, indicating a problem with the engine management system

• Engine Knock or Misfires: Incorrect valve timing caused by a faulty CMP sensor can lead to misfires, which are irregular combustion events in the engine cylinders

• Reduced Fuel Efficiency: Incorrect valve timing can lead to incomplete combustion, wasting fuel and reducing fuel economy

Table 3.28: DTC relate to Camshaft position sensor

Table 3.29: Standard resistance of camshaft position sensor

Checking terminal Voltage (power source of Camshaft position sensor (for intake camshaft)

Step 1: Disconnect the camshaft position sensor (for intake camshaft)

Step 2: Turn the ignition switch to ON

Step 3: Measure the Voltage according to the value in the table below

DTC No Detection Item Trouble Area

Sensor Circuit ã Open or short in camshaft position sensor circuit (for intake camshaft) ã Camshaft position sensor (for intake camshaft) ã Intake camshaft ã Jumped tooth of timing chain for intake camshaft ã ECM P0342

Low Input (Bank 1 or Single Sensor) ã Open or short in camshaft position sensor circuit (for intake camshaft) ã Camshaft position sensor (for intake camshaft) ã ECM P0343

High Input (Bank 1 or Single Sensor) ã Open or short in camshaft position sensor circuit (for intake camshaft) ã Camshaft position sensor (for intake camshaft) ã ECM

Table 3.30: Standard Voltage of power source of Camshaft position sensor (for intake camshaft)

Tester Connection Switch Condition Specified Condition

B45-3 (VC) - Body ground Ignition switch ON 4.5 to 5.5 V

Figure 3.47: Front view of wire harness connector (to Camshaft Position Sensor (for

Intake Camshaft) Checking harness and connector

Step 1: Disconnect the B45 camshaft position sensor (for intake camshaft) connector

Step 2: Disconnect the B46 ECM connector

Step 3: Measure the Resistance according to the value in the table below

Table 3.31 Standard Resistance of harness and connector of Camshaft position sensor and ECM connector

Tester Connection Condition Specified Condition

B45-1 (VVI+) - B46-23 (VV1+) Always Below 1 Ω B45-2 (VVI-) - B46-22 (VV1-) Always Below 1 Ω B45-1 (VVI+) or B46-23 (VV1+) -

Body ground and other terminals Always 10 kΩ or higher B45-2 (VVI-) or B46-22 (VV1-) -

Body ground and other terminals Always 10 kΩ or higher

Check the camshaft position sensor (for intake camshaft) installtion condition It is

OK when camshaft position sensor is installed corectly

Inspecting intake camshaft (timing rotor)

Checking the timing rotor of the intake camshaft It is OK when camshaft timing rotor does not have any cracks or deformation

Checking valve timing (check for loose timing chain and jumped tooth)

Step 1: Remove the cylinder head cover sub-assembly

Step 2: Turn the crankshaft pulley and align its groove with the "0" timing mark of the timing chain cover

Step 2: Check that the timing marks of the camshaft timing gear assembly and camshaft timing exhaust gear assembly are at the positions shown in the illustration

If not, turn the crankshaft 1 revolution (360°) to align the timing marks as shown in the illustration

If the result is not as specified, check for mechanical malfunctions that may have affected the valve timing, such as a jumped tooth or stretching of the timing chain

Check for mechnical malfunctions that affect the vavle timing, such as jumped tooth or stretching of the timing chain

*b No 1 Cylinder at TDC Compression

FUEL INJECTION AND IGNITION SYSTEM OF TOYOTA VIOS 2022

Fuel injection

The 2NR-FE engine utilizes a Sequential Fuel Injection (SFI) system, a specific type of fuel injection technology with its own unique characteristics and benefits

Unlike traditional "simultaneous" fuel injection systems where all injectors open and close simultaneously, SFI systems inject fuel sequentially, one cylinder at a time This means that each injector opens and closes in precise coordination with the specific intake and exhaust valve opening and closing events for each cylinder

Advantages of SFI in the 2NR-FE Engine:

• Improved fuel efficiency: SFI allows for more precise fuel metering to each cylinder based on its individual needs This minimizes wasted fuel and optimizes combustion efficiency, leading to better fuel economy compared to simultaneous injection systems

• Reduced emissions: Precise fuel control also contributes to cleaner combustion, minimizing the emission of harmful pollutants like unburned hydrocarbons and carbon monoxide

• Enhanced performance: By ensuring optimal fuel delivery for each cylinder, SFI contributes to smoother engine operation, improved power output, and increased torque generation

• Better cold starting: The ability to adjust fuel delivery for individual cylinders during cold starts helps the engine warm up faster and achieve stable idle sooner

Technical aspects of the 2NR-FE's SFI System:

• Individual injectors: Each cylinder has its dedicated injector, allowing for precise control of fuel delivery

• High-pressure fuel pump: The SFI system requires a high-pressure fuel pump to deliver the fuel to the injectors with sufficient force for proper atomization and mixing with air

• ECM control: The Engine Control Module (ECM) plays a vital role in the SFI system It analyzes sensor data like intake air temperature, engine load, and crankshaft position to calculate the optimal fuel quantity and timing for each injection event

• Variable pulse width: The ECM can adjust the duration of the injector opening (pulse width) to precisely control the amount of fuel injected into each cylinder based on its specific needs

Components and their Structure of SFI system:

• Fuel Tank: This secure reservoir stores the gasoline, readily available for the engine's needs

• Fuel Pump: This electric pump draws fuel from the tank and delivers it under pressure to the fuel rail It ensures consistent fuel supply regardless of engine load or driving conditions

• Fuel Pressure Regulator: This component maintains a constant fuel pressure regardless of engine load or demand and ensures optimal fuel delivery pressure for proper injector operation

*1 Fuel pressure regulator assembly *2 Fuel pump

*3 Fuel pump harness *4 Fuel sender gauge assembly

*5 No 1 fuel suction support *6 No 2 fuel suction support

*7 Fuel pump spacer *8 Fuel pump filter

*9 Fuel suction tube assembly *10 O-ring

• Fuel Filter: This component removes impurities and contaminants from the fuel before it reaches the injectors, preventing clogging and ensuring smooth system operation

• Fuel Rail: This hollow pipe distributes pressurized fuel equally to all fuel injectors

Figure 4.4: Fuel Rail and Fuel Injectors

• Fuel Injectors: These precisely engineered nozzles, mounted on the intake manifold, atomize the fuel into a fine mist This optimizes mixing with air for efficient and complete combustion The injectors are controlled by the Engine Control Module (ECM) to deliver the exact amount of fuel needed for each cylinder based on engine load and operating conditions

*7 O-ring N*m (kgf*cm, ft.*lbf): Specified torque

• Intake Manifold: This passageway channels air from the air filter to the cylinders and distributes the fuel-air mixture evenly

• Engine Control Module (ECM): This "brain" of the system analyzes various sensor data (engine temperature, air intake volume, etc.) and calculates the precise amount of fuel each injector needs to deliver for optimal combustion under any operating condition It sends signals to the fuel injectors, controlling the opening and closing of their nozzles for precise fuel metering

• Heated Oxygen Sensor (O2 Sensor): This sensor monitors the exhaust gas oxygen content and relays this information to the ECM The ECM uses this data to adjust the fuel mixture for optimal combustion efficiency and minimize emissions

Location of these components on Toyota Vios 2022:

Figure 4.6: Fuel system parts position

*1 Fuel injector assembly *3 Fuel sender gauge assembly

- main fuse *4 Fuel suction tube with pump and gauge assembly

2NR-FE engines work by sucking a mixture of gasoline and air into a cylinder, compressing it with a piston, and igniting it with a spark The resulting explosion drives the piston downwards, producing power Traditional indirect fuel injection systems pre- mix the gasoline and air in a chamber just outside the cylinder called the intake manifold

In a direct injection system, the air and gasoline are not pre-mixed Rather, air comes in via the intake manifold, while the gasoline is injected directly into the cylinder with the controlling of vehicle computer

Figure 4.7: Wiring diagram of fuel injection system

When the starter switch is closed, pin B+ in the ECM goes in the Driver side junction block assembly Then, the electric flows in two ways, one way is one pin of the contact

103 point of the EFI relay, one way is that of C/OPN relay After receiving adequate information from others system, ECM orders the fuel to be fed into the chambers through MREL pin (injector control signal) and FC pin (Fuel pump control signal) When FC pin provides 5 voltage goes through the coil of C/OPN relay, the contact point is closed, the waiting electric will be provided to the fuel pump When MREL pin is provided 5 voltages which goes through the coil of EFI relay, the contact point closed, the waiting electric will also be provided to the injectors With the feeding of the fuel pump and the pulses come from MREL pin of the ECM, fuel will be injected to the cylinder precisely depending on every working condition of the vehicle

Figure 4.8: Wiring diagram of fuel system

The Sequential Fuel Injection (SFI) system in the Toyota 2NR-FE engine plays a crucial role in delivering precise amounts of fuel to each cylinder, optimizing performance and efficiency However, when components within the SFI system malfunction, a variety of symptoms can arise, indicating the need for diagnosis and repair Here's a detailed breakdown of common failure symptoms and their potential causes:

• Rough idling and hesitation: This can be caused by a faulty fuel injector, clogged fuel filter, or malfunctioning Idle Air Control (IAC) valve

• Loss of power and acceleration: A failing fuel pump, clogged fuel injectors, or malfunctioning Oxygen Sensor (O2 sensor) can lead to inadequate fuel delivery, resulting in power loss

• Engine stalling: This can occur due to a faulty fuel injector, clogged fuel filter, or malfunctioning IAC valve, causing inconsistent fuel delivery and disrupting engine idle

• Increased emissions: A malfunctioning O2 sensor, clogged fuel injectors, or faulty Mass Airflow Sensor (MAF sensor) can lead to incorrect fuel mixtures, resulting in higher emissions

• Poor fuel economy: Clogged fuel injectors, faulty fuel pump, or malfunctioning O2 sensor can cause inefficient fuel delivery and combustion, leading to decreased fuel economy

Check terminal voltage (power source of fuel injector assembly):

Figure 4.9: Front view of wire harness connector (to Fuel Injector Assembly)

Step 1: Disconnect the fuel injector assembly connectors

Step 2: Turn the ignition switch to ON

Step 3: Measure the voltage according to the value(s) in the table below

Table 4.1: Standard Voltage of power source of fuel injector assembly

Tester Connection Switch Condition Specified Condition

B4-1 - Body ground Ignition switch ON 11 to 14 V B5-1 - Body ground Ignition switch ON 11 to 14 V B6-1 - Body ground Ignition switch ON 11 to 14 V B7-1 - Body ground Ignition switch ON 11 to 14 V

If the voltage of the system meets the requirement, technician will check the injection and its volume by inspecting the fuel injector assembly

If the voltage of the system not meet the requirement, technician will check the harness and connector of IG2 relay and fuel injector or from the fuel injector to the ignition or that of starter switch

Inspect fuel injector (resistance, injection and volume)

Check resistance of the injector:

Step 1: Turn the ignition to OFF

Step 2: Disconnect the electrical connector to the injector

Step 3: Connect two probes of the multi-meter to two pins of the injector

If the meter reads infinite resistance, the coil in the injector is opened

If the reading is jumping all over the place, the coil is partially opened

If the reading is zero resistance, the coil is shorted

Check the injection and volume of the injector:

Step 1: Check the leak of the injector (on the injector body and nozzle)

Step 3: Flow spray pattern verification (Even if the spray pattern is not affected by deposits, it is still possible for internal deposits and/or corrosion to cause variations in flow rate)

Check harness and connector (from ECM to fuel injector assembly)

Inspect by using multi-meter:

Step 1: Disconnect the B4, B5, B6 and B7 fuel injector assembly connectors

Step 2: Disconnect the B47 ECM connector

Step 3: Measure the resistance according to the value(s) in the table below

Table 4.2: Standard resistance of harness and connector from ECM to fuel injector assembly

Tester Connection Condition Specified Condition

B47-4 (#10) - B4-2 Always Below 1 Ω B47-3 (#20) - B5-2 Always Below 1 Ω B47-2 (#30) - B6-2 Always Below 1 Ω B47-1 (#40) - B7-2 Always Below 1 Ω

B47-4 (#10) or B4-2 - Body ground and other terminals Always 10 kΩ or higher

B47-3 (#20) or B5-2 - Body ground and other terminals Always 10 kΩ or higher

B47-2 (#30) or B6-2 - Body ground and other terminals Always 10 kΩ or higher B47-1 (#40) or B7-2 - Body ground and other terminals Always 10 kΩ or higher

Check by using testing light

Step 2: Turn the ignition switch to ON

Step 3: Attach the terminal of the harness connector with the testing light

Step 4: Plug the harness connector back onto the fuel injector and hook the test lighting clip to the positive side of the battery

Step 6: Back-probe the opposite wire on the fuel injector connector (this is the pulse signal coming from the computer)

Step 7: Observe the testing light

This time, the testing light should flash, which means the injector is receiving the pulse signal from the computer to open and close the injector

Check harness and connector (from ECM to body ground)

Step 1: Disconnect the B46 ECM connector

Step 2: Measure the resistance according to the value(s) in the table below

Table 4.3 Standard resistance of harness and connector from ECM to body ground

Tester Connection Condition Specified Condition

B46-1 (E01) - Body ground Always Below 1 Ω B46-2 (E02) - Body ground Always Below 1 Ω

Check harness and connector (from IG2 relay to fuel injector)

Step 1: Remove the IG2 relay from the NO 4 relay block

Step 2: Disconnect the B4, B5, B6 and B7 fuel injector connectors

Step 3: Measure the resistance according to the value(s) in the table below

If the result is OK, move to the next test

Table 4.4: Standard resistance of harness and connector from IG2 relay to fuel injector

Tester Connection Condition Specified Condition

5 (IG2 relay holder) - B4-1 Always Below 1 Ω

5 (IG2 relay holder) - B5-1 Always Below 1 Ω

5 (IG2 relay holder) - B6-1 Always Below 1 Ω

5 (IG2 relay holder) - B7-1 Always Below 1 Ω

5 (IG2 relay holder) or B4-1 - Body ground and other terminals Always 10 kΩ or higher

5 (IG2 relay holder) or B5-1 - Body ground and other terminals Always 10 kΩ or higher

5 (IG2 relay holder) or B6-1 - Body ground and other terminals Always 10 kΩ or higher

5 (IG2 relay holder) or B7-1 - Body ground and other terminals Always 10 kΩ or higher

Check harness and connector (fuel injector to ignition switch)

Step 1: Disconnect the B4, B5, B6 and B7 fuel injector assembly connectors

Step 2: Disconnect F7 ignition or starter switch assembly connector

Step 3: Measure the resistance according to the value(s) in the table below

Table 4.5: Standard resistance of harness and connector fuel injector to ignition switch

Tester Connection Condition Specified Condition

B4-1 - F7-6 (IG2) Always Below 1 Ω B5-1 - F7-6 (IG2) Always Below 1 Ω B6-1 - F7-6 (IG2) Always Below 1 Ω B7-1 - F7-6 (IG2) Always Below 1 Ω

B4-1 or F7-6 (IG2) - Body ground and other terminals Always 10 kΩ or higher

B5-1 or F7-6 (IG2) - Body ground and other terminals Always 10 kΩ or higher

B6-1 or F7-6 (IG2) - Body ground and other terminals Always 10 kΩ or higher

B7-1 or F7-6 (IG2) - Body ground and other terminals Always 10 kΩ or higher

Measure the resistance according to the value(s) in the table above

Result: If the result is not as specified, replace the fuel injector assembly

Step 2: Inspect the fuel injector injection volume

Figure 4.11: Component without harness connected

Ignition System

The Toyota 2NR-FE engine utilizes a direct ignition system, which differs from traditional ignition systems in several key aspects Understanding these differences is crucial for appreciating the advancements and potential benefits of this technology

Key Differences from Traditional Ignition Systems:

• Individual ignition coils: Unlike traditional systems with a single coil and distributor cap, the direct ignition system employs individual coils for each spark plug This eliminates the need for spark plug wires and distributor cap, simplifying the system and minimizing potential failure points

• Coil-on-Plug design: Each coil directly mounts onto the spark plug, resulting in a more compact and efficient design This reduces losses due to resistance in spark plug wires and ensures precise spark delivery to each cylinder

• Dwell time optimization: The ECM can independently control the dwell time (duration of current flow) for each coil, optimizing spark energy based on engine operating conditions and individual cylinder needs This leads to improved fuel efficiency and performance across varying RPM ranges

• Knock sensor integration: The ECM analyzes data from the knock sensor to detect engine knock (premature ignition) and adjust spark timing accordingly This prevents engine damage and optimizes combustion for maximum efficiency

Benefits of Direct Ignition System:

• Improved performance: The direct system provides a more powerful and consistent spark, leading to increased engine power and responsiveness

• Enhanced fuel efficiency: Optimized spark timing and improved combustion efficiency contribute to better fuel economy

• Reduced emissions: Precise spark control minimizes harmful emissions through cleaner combustion

• Simplified design: Eliminating the distributor cap and spark plug wires simplifies the system, making it more compact and reliable

• Easier maintenance: Individual coils are easier to access and replace compared to traditional systems with a single coil and distributor

In the new generation of ECU spark management systems on Toyota Vios 2022, it provides more precise control of ignition spark timing The centrifugal and vacuum advances are eliminated; replaced by the engine sensors which help engine to monitor its load (Vs or PIM) and speed (Ne) Additionally, some sensors are monitored namely coolant temperature, knock, and throttle position to provide exact signals for better spark accuracy as these conditions change

The Toyota Vios 2022 2NR-FE engine, a 1.5-liter, 4-cylinder powerhouse, relies on a sophisticated ignition system to initiate combustion within its cylinders This system ensures precise spark delivery for optimal performance, fuel efficiency, and minimized emissions Understanding the structure and function of this intricate system is crucial for maintaining engine health and addressing potential issues

Components of Direct Ignition System:

The 2NR-FE engine's ignition system is comprised of several key components, each playing a vital role in the combustion process:

• Ignition switch: This driver-controlled switch serves as the entry point for the entire system Turning the key to the "start" position completes the circuit, initiating the process

• Battery: The battery acts as the power source, supplying the 12-volt DC current needed to energize the entire ignition system

• Ignition coil: This transformer converts the low-voltage DC current from the battery into a high-voltage pulse (around 20,000 volts) required for spark generation Suddenly interrupting this current induces a high voltage in the secondary winding, which is then transferred to the spark plugs via the spark plug wires

• Spark plug wires: These high-voltage wires, made of insulated copper and enclosed in a protective sheath, channel the electrical

• Spark plugs: These threaded components screw into the cylinder head, positioning the electrode gap directly above the air-fuel mixture within the combustion chamber

• Crankshaft position sensor (CKP sensor): This sensor monitors the crankshaft's rotational position and transmits the information to the Engine Control Module (ECM)

• Camshaft position sensor (CMP sensor): This sensor tracks the camshaft's rotational position and relays this information to the ECM Similar to the CKP sensor, this data assists the ECM in determining the precise timing for spark generation, ensuring synchronization with the valve opening and closing events

• Engine control module (ECM): The ECM serves as the brain of the entire system, coordinating the operation of all components for optimal performance.

A direct ignition system is used on this vehicle The direct ignition system is a cylinder ignition system which ignites one cylinder with one ignition coil In the cylinder ignition system, one spark plug is connected to the end of the secondary winding High voltage is generated in the secondary winding and is applied directly to the spark plug The spark of the spark plug passes from the center electrode to the ground electrode

When the engine starts running with the ignition switch on, power is supplied by the battery, grounding the negative terminal and connecting the positive terminal to the ignition switch This power is directed to the ignition coil, consisting of primary and secondary windings An iron rod between the windings generates a magnetic field As the armature rotates, connected to the electronic module, a magnetic pick-up occurs, creating a voltage signal The voltage signal intensifies until a strong one is generated [17]

Next, the voltage is sent to the distributor, housing a rotor and distributor points set as per ignition timing As the rotor aligns with a distributor point, the voltage jumps through the air gap from the rotor to the distributor point and is then transmitted to the adjacent spark plug terminal via the high-tension cable This generates a voltage difference between the central and ground electrodes of the spark plug, leading to a spark at the tip of the spark plug, initiating combustion [17]

The ECM determines the ignition timing and transmits the ignition signals for each cylinder Using the ignition signal, the ECM turns on and off the power transistor inside the igniter, which switches on and off a current to the primary coil When the current to the primary coil is cut off, high voltage is generated in the secondary coil and this voltage is applied to the spark plugs to create sparks inside the cylinders

Figure 4.17: Wiring diagram of ignition system

A distributor is not present in Vios 2022 direct ignition system (often referred to as DIS) The 2NR-FE engine management system regulates the ignition timing, and the HT leads connect straight from the coil to the spark plugs for each of the engine's cylinders

When the engine is cranked, an alternating current signal is generated by a 24-tooth

Ne pickup and a four-tooth G pickup These signals are sent to the managed computer where they are conditioned and relayed to the microprocessor

A trigger circuit is monitored by the microprocessor, referred to as IGT (TR1) Then, this IGT signal is sent to the igniter to switch the primary circuit power transistor on and off

CONCLUSION

Conclusion

After being accomplished, the main work of this project is summarized:

Data from multiple vital engine sensors are combined to produce depth information for precisely working of the engine, then the inspected preparation is employed to achieve target performance

Successful evaluation of engine parameters for knowledge of the model vehicle; the model’s output is further meet the project requirements;

Repairing manual that studied gives meaningful method to inspect, repair the vehicle with the standard quality from Toyota;

Succesfully applying the knowledge from the technical subjects to research the working principle of control engine systems;

Introducing of a comprehensive framework that integrates vehicle engine and inspection, and evaluating to enhance the power of the engine.

Future Work

Despite achieving the target objectives, this project remains some key limitations to be overcome in the future:

Improvement of state weaknesses for 2NR-FE engine

Introducing of how engine works in chosen conditions

Evaluating the research system by using proved formula

Solutions for real-time applications of the engines.

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