Section Engine Control Systems Slide 25 T852f001 Air Induction Air induction systems measure and control the air entering the cylinders Systems They include: • The air flow sensor (commonly called the mass air flow sensor) measures air after it has been filtered by the air cleaner • The throttle valve regulates the volume of air entering the induction system (based on driver demand) • The air intake chamber and intake manifold are tuned for efficient engine operation There are many variations on the basic air induction system, such as: • Electronic Throttle Control System-intelligent (ETCS-i) allows the ECM to adjust throttle opening according to driver demand and vehicle conditions • Acoustic Control Induction System (ACIS) allows the ECM to vary the effective intake runner length for better engine performance • Variable Valve Timing-intelligent (VVT-i) allows the ECM to adjust when the valves open for optimum engine performance at varying speeds Toyota Engine Control Systems I Course 852 23 Fuel Systems Engine Control Systems Slide 26 T852f002 Fuel Systems Fuel systems deliver the correct volume of fuel to the cylinders to satisfy a variety of engine operating conditions Fuel system components include: • A fuel pump pressurizes fuel for use by the fuel injectors • A fuel pressure regulator, located in the fuel tank or after the injectors, regulates fuel pressure • The fuel injectors, when on, allow fuel to flow into the intake manifold The ECM calculates: • How much fuel to be injected • When to inject fuel These calculations are based on a variety of factors, primarily intake air volume and temperature The ECM also calculates fuel injection duration and timing based on engine RPM, crankshaft position, and engine load Other system components that modify fuel injection operation are detailed in the Fuel Systems section 24 TOYOTA Technical Training Ignition Systems Engine Control Systems Slide 27 T852f003 Ignition Systems The ECM is programmed to monitor engine operating conditions and determine the optimum time to ignite the air/fuel mixture • Based on a signal from the ECM, the igniter starts and stops current through the ignition coil(s) by providing and taking away a path to ground • When coil current is turned OFF, high voltage is generated in the coil • High voltage applied to the spark plug creates the spark needed for ignition Toyota Engine Control Systems I Course 852 25 Exhaust and Emission Control Systems Engine Control Systems Slide 28 T852f004 Exhaust/Emission Control Systems The ECM manages systems and components to meet state and federal regulations Systems may include: • The evaporative system (EVAP) prevents hydrocarbons (HC) from entering the atmosphere • Variable Valve Timing with intelligence (VVT-i) improves engine performance while lowering engine emissions, primarily oxides of nitrogen (NOx) • The fuel control program adjusts the air/fuel ratio so the catalytic converter runs at peak efficiency This lowers HC, carbon monoxide (CO), and NOx emissions • The exhaust gas recirculation system (EGR) feeds a small amount of exhaust gas back into the air induction system to reduce combustion chamber temperature, lowering NOx EGR has been phased out as other control systems accomplish the same function 26 TOYOTA Technical Training ... ignition Toyota Engine Control Systems I Course 852 25 Exhaust and Emission Control Systems Engine Control Systems Slide 28 T852f004 Exhaust/Emission Control Systems The ECM manages systems and...Fuel Systems Engine Control Systems Slide 26 T852f002 Fuel Systems Fuel systems deliver the correct volume of fuel to the cylinders to satisfy a variety of engine operating conditions... on engine RPM, crankshaft position, and engine load Other system components that modify fuel injection operation are detailed in the Fuel Systems section 24 TOYOTA Technical Training Ignition Systems