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LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2) LV22 ignition systems (2)
kap all phase & 6/11/03 11:35 am Page Student Workbook LV22 Ignition Systems (2) LV22/SWB Student Workbook for Technical Certificates in Light Vehicle Maintenance and Repair MODULE LV22 IGNITION SYSTEMS (2) Contents Page Introduction Secondary Voltage Requirements: Progress check Cylinder pressure and mixture strength Exercise Electronic Ignition System: Ignition trigger signals – inductive Exercise Ignition trigger signals – Hall effect Ignition triggers – optical 10 10 12 14 Dwell Period and Current Limiting 15 Electronic Ignition Systems 16 Computerised Ignition Systems 17 Page Test Methods for Conventional Ignition System: Ignition coil tests Spark plug and high-tension cord tests Distributor cap/rotor arm Contact breaker points adjustment Vacuum and governor advancer tests Battery test -1Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue 19 19 21 23 24 25 26 -2Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Introduction Conventional ignition systems have now been replaced by electronic ignition systems The advantage that an electronic system has over a conventional system is that the mechanical operation of the contact breaker points, used to interrupt the primary circuit of the ignition coil, is now carried out by electronic components Transistors are used to interrupt the primary circuit on receiving a trigger signal from the distributor The signal generators are housed within the distributor and there are three types used at present; inductive (magnetic) trigger, Hall effect trigger and the optical trigger Each of these will be discussed during this phase of ignition systems As transistors are now used in place of contact breaker points, the metal-to-metal contact associated with the opening and closing of the point is eliminated This reduces the number of components that need to be checked during routine servicing and eliminates the secondary voltage drop associated with a conventional contact breaker system -3Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Secondary Voltage Requirements Approx 3kV Approx 5kV Firing voltage at spark plug dictated by cylinder pressure When the ignition coil produces the secondary voltage, the voltage will travel to earth via the path with the least resistance In the secondary circuit, the earth path for the secondary voltage is via the ignition coil high-tension cord, (usually referred to as the “king lead”), through the distributor (via the rotor arm) to the spark plug and finally across the spark plug gap, creating the spark/flame to ignite the air/fuel mixture If a path exists with less resistance than that of the ignition system hightension circuit, the secondary voltage will pass through it, bypassing the spark, resulting in a misfire It is therefore important that no other path exists except that of the designated path to the spark plug Additional resistances are normally fitted to high-tension cords, spark plugs etc to prevent electrical interference affecting electronic systems -4Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Progress check Answer the following questions: What secondary voltage is necessary to overcome the rotor arm? What secondary voltage is necessary to overcome the spark gap? What will dictate the secondary voltage at the spark plug? -5Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Cylinder Pressure and Mixture Strength The lower the cylinder pressure, the lower the secondary voltage required to jump the spark plug gap The higher the cylinder pressure, the higher the secondary voltage required to jump the spark plug gap As with cylinder pressure, mixture strength also affects the strength of the secondary current needed to enable the air/fuel mixture to burn The richer the mixture the lower the secondary voltage needed to jump the spark gap The leaner the mixture the higher the secondary voltage required to jump the spark gap -6Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Exercise Ignition waveform Identify the components of the secondary waveform and add a description of each component: Identify the components of the primary waveform and add a description of each component: -7Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue The current limiting hump can be seen in the dwell section of the waveform The coil charge period is between the start of dwell and the current limiting hump When the engine speed is low i.e engine at idle, the dwell angle is short When the engine speed is increased, the start of the dwell period has moved to the left, increasing the dwell angle with an increase in engine speed The current limiting hump can be seen to move to the right as the engine speed is increased The ignition coil charge time becomes longer with an increase in engine speed When the engine speed is increased further, the start of the dwell period moves further to the left When the engine speed increases further, the current limiting hump can be seen to disappear, as the coil requires the full dwell period to charge fully The ignition timing does not alter with an increase in dwell as only the start of dwell changes With later engine management systems, the current limiting hump may not be seen in the waveform -8Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Electronic Ignition System Electronic earth switch Trigger Points – mechanical signal earth switch It has been seen that with a contact breaker ignition system, the ignition coil circuit is completed by a set of contact breaker points The contact breakers switch the primary circuit of the coil to earth The circuit can be referred to as an earthed switched circuit The contact breaker points are mechanically opened by a cam and closed by a spring, which is rotated by the distributor shaft The rotation of the shaft/cam allows the points to open and close at the correct time in relation to the engine cylinder cycle With an electronic ignition system, the ignition coil is switched to earth, however an electronic switch replaces the mechanical switch The electronic switch is normally referred to as an ignition amplifier or in some applications an igniter (Japanese manufacturers) The electronic ignition coil circuit can therefore still be referred to as an earth switched circuit The amplifier is in effect an ECU (Electronic Control Unit) Its sole purpose is to switch the coil on and off at the correct time If it is to this successfully, it needs to know where the pistons are in respect of the stroke cycle at any given time A sensor provides this information, and is generally referred to as the trigger mechanism The trigger is normally located in the distributor body, and the trigger signal passes directly to the ignition amplifier There are typically three types of ignition trigger device that are used by electronic ignition systems: • inductive (magnetic) trigger (or sensor) • Hall effect trigger (or sensor) • optical trigger (or sensor) On some earlier vehicles, the trigger was located next to the flywheel or crank pulley -9Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue The rotation of the rotor near to the trigger causes an AC current to be produced Ignition trigger signals – Hall effect The Hall drum is connected to the distributor shaft When the distributor shaft rotates, the drum rotates The drum has cut-outs; the number of cut-outs correspond to the number of engine cylinders i.e four cut-outs are used on a cylinder engine -12Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue + O _ The Hall switch is an integrated circuit (IC), which is affected by magnetism The illustration shows an open/close switch which we will use to represent the Hall IC The Hall switch receives a power supply at the “+” terminal The “-” terminal is connected to earth (usually via the amplifier) The amplifier passes a signal voltage to the “O” terminal (typically between 5-10 volts) The amplifier uses any changes experienced in this voltage as a signal to switch the ignition coil on or off High voltage When the solid section of the drum passes between the magnet and the Hall switch, magnetism cannot influence the Hall switch If magnetism cannot influence the Hall switch, the Hall switch will be open When the switch is open, the signal current cannot flow to earth, therefore the signal voltage at Hall switch terminal “O” will be high (and also at the corresponding amplifier terminal) Switch circuit voltage low – Earth circuit When the cut-out section of the drum passes between the magnet and the Hall switch, magnetism can influence the Hall switch If magnetism influences the Hall switch, the Hall switch will close When the switch is closed, the signal current can now flow to earth The signal voltage at the Hall switch terminal “O” will be zero (and also at the corresponding amplifier terminal) -13Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Ignition triggers – optical As with the previous two trigger systems, the optical trigger replaces the conventional contact breaker point The basic system parts are the segmental trigger or chopper wheel, which is connected to the distributor cam, the infrared light and the phototransistor The infra-red light, which is a gallium arsenide cell, is kept at a constant intensity by a zener-diode which acts as a stabiliser Infra-red light is then collected by the phototransistor which is constructed of silicon and connected to a second transistor The two transistors that are now connected together form a Darlington amplifier Infra-red light is collected by the phototransistor causing it to be switched on, this signal is then sent to the ignition amplifier As the chopper wheel rotates, it interrupts the flow of light to the phototransistor thus causing the phototransistor to be switched on and off There are as many segments on the chopper wheel as there are cylinders and they are sized to give exactly 66% dwell -14Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Dwell Period and Current Limiting Ignition coil 0.5 ohms Current limiting is used with many electronic ignition systems Contact breaker ignition systems fitted with a low resistance ignition coil (1.5 ohms) used a ballast resistor to limit the current in the ignition coil primary circuit It does beg the question ‘Why not just use a high resistance coil?’ The use of a resistor enables us to bypass it during cranking to give a decent spark when the battery voltage is low (because we are cranking) and then reintroduce it during normal running to prevent coil damage when battery voltage is high (charging) A low resistance coil has less windings on the primary side This has the added advantage of producing less counter electromotive force during coil charge/discharge resulting in a better spark A resistor has no windings and therefore produces no counter electromotive force The current flow in an electronic ignition system can be limited to a predetermined value by the ignition amplifier If a low resistance coil were to be used (0.5 ohms), there could be 24 amps flowing in the ignition coil primary circuit This could damage the electrical components and wiring Advantages of using current limiting ignition system: • lower coil resistance (0.5 - 0.75 ohms) • rapid charging of the ignition coil • amplifier limits the current flow after predetermined value is reached • no external ballast resistor is necessary • variable dwell/ current limiting = “constant energy” -15Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Electronic Ignition Systems Amplifier / Igniter Inductive sensor Amplifier / Igniter +0Hall effect sensor -16Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Computerised Ignition Systems Water temperature sensor Manifold Absolute Pressure sensor The next stage in the development of a modern car’s ignition system was to fully computerise the ignition system The ignition amplifier has been incorporated with the Electronic Control Unit (ECU) The engine speed and engine position signal, usually provided by the distributor trigger, has typically been replaced by a crankshaft trigger/sensor The crankshaft sensor can provide an engine speed signal and the exact position of the crankshaft We also supply the ECU with many other pieces of information such as engine temperature and engine load The timing can be altered dependent on engine operating conditions, which can provide better performance and improved fuel economy The timing can also be optimised for different fuel octane ratings These computerised ignition systems are often linked to electronically controlled fuel systems Two other versions of fully computerised ignition systems, are distributor-less or wasted spark ignition systems and direct ignition systems -17Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Distributor-less or wasted spark ignition systems use an individual coil for each of two cylinders, an ignition amplifier, (that in turn is controlled by the engine electronic control unit), controls the coil In some cases the coil is controlled directly by the engine’s electronic control unit The electronic control unit sends a signal to the amplifier causing current to travel through the primary coil The length of time that the signal is sent is dependent on information received from the crankshaft and camshaft sensors These two sensors allow the electronic control unit to know the engine speed and piston position At the correct time the signal is switched causing secondary voltage to be generated The secondary voltage/current is then sent to two plugs simultaneously, one being fired in the compression stroke and the other in the exhaust stroke This eliminates the need for a distributor Direct ignition systems are now becoming commonplace with most manufacturers The latest systems now place the ignition coils directly onto the spark plugs This eliminates not only the need for distributors but also high-tension cords By eliminating these two items the two main potential areas for current drop are removed, making the system more reliable This type of system also allows for greater control over when the spark is delivered, as each spark plug is now operated individually -18Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Testing Methods for Conventional Ignition System Ignition coil tests Ω The primary coil can be checked for serviceability by the use of an ohmmeter The high-tension cord, together with any wires connected to the coil, must be removed The ohmmeter must then be connected between the positive and negative terminals of the coil The reading taken must be compared with the manufacturers’ specification Ω As with the primary coil, the secondary coil can also be checked using an ohmmeter, but the probes are placed as per the diagram The reading obtained must again be compared with the manufacturers’ specification Ω The final resistance check is carried out on the ballast resistor, if one is fitted to the system The probes are this time connected across the ballast resistor The reading must be taken and compared with the manufacturers’ specifications -19Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Voltage checks also need to be carried out as the coil will not operate if the voltage is to low If the voltage drops below approximately eight volts then insufficient current will travel through the primary coil causing secondary voltage to be low This will lead to engine misfire V Turn the ignition switch to the on position, and connect the voltmeter between the positive terminal of the ballast resistor and body ground If a ballast resistor is not fitted then carry out the next test, both with the ignition on and in the start position Approximately 12 volts should be shown on the meter V Finally connect the voltmeter between the positive terminal of the coil and body ground Place the ignition in the start position and approximately 12 volts should be displayed If the reading is incorrect then check the wire harness -20Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Spark plug and high tension cords test Before any tests are carried out on the spark plugs a visual inspection of the spark plugs must be carried out When this has been completed the electrode gap must be checked While visually checking the spark plugs attention must be paid to both the condition and colour around the two electrodes • If the engine and spark plugs are operating correctly then there will be grey-brown deposits around the electrode The electrode gap should have increased but only by approximately 0.025mm per 1000 miles • When the electrode is contaminated with dry, black, sooty deposits, then carbon fouling is the most probable cause Carbon fouling is usually caused by an over-rich mixture, which in turn will cause a weak spark With the introduction of electronic fuel injection this problem has almost been eliminated, but with engines fitted with carburettors the problem still remains • Oil fouling of the plugs is associated with worn engine components The most common entry points for oil into the combustion chamber, are either past the piston rings (due to either cylinder bore or piston ring wear), or past the valves (due to wear in the valve guides or valve stems) When this problem occurs the plug electrode will be coated in a wet oily deposit and will be black in colour • Overheating of the spark plugs also leaves a visible sign on the electrodes The electrodes become glazed with a white appearance This fault is usually caused by incorrect ignition timing, which causes the combustion pressure and temperature to rise excessively -21Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Electrode gap When the visual inspection has been carried out, then the spark plugs must be cleaned if necessary, and then the electrode gap must be checked The electrode gap will vary depending on the type of ignition system and the type of engine with which the spark plug is being used Manufacturers’ specifications must be used for the spark plug gap When the specification for the spark plug gap has been obtained, then the correct feeler blade must be selected and placed in the electrode gap As the feeler blade is placed in the gap there should be a small amount of friction between the blade and the electrode If the gap is incorrect then the gap must be adjusted An incorrect electrode gap will cause incorrect operation of the spark plug leading to engine misfire After the spark plug has been checked and the electrode gap set, spark checks can be used to check both the high-tension cords and the operation of the spark plugs Remove the spark plugs from the engine and then refit them to the high-tension cords Hold the spark against the engine or body ground and then turn the engine over A spark should be generated across the electrode gap If a spark is not generated then both the spark plug and the high-tension cords can be substituted with new components, one at a time, to decide which component is faulty Complete this test for all spark plugs, if none of the spark plugs are sparking then the fault is earlier in the ignition system This type of test can also be used to test the operation of the ignition coil and high-tension cord between the coil and distributor -22Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Disconnect the high-tension cord that is fitted between the ignition coil and the distributor at the distributor end Hold the metal end of the high-tension cord approximately 10mm from a good body ground and turn over the engine A good spark should be generated while the engine is turning If no spark is generated then the high-tension cord should be checked for serviceability, and if this is found to be correct then the ignition coil checks should be carried out Ω Checking the serviceability of the high-tension cords is a relatively easy task A resistance check needs to be carried out on each individual high-tension cord, both when connected to the distributor cap and when removed from it An ohmmeter should be used to this The two test probes from the ohmmeter should be placed one at either end of the high-tension cord and a reading should then be taken This should then be repeated for each of the high-tension cords, and a reading of no higher that 25kΩ should be obtained When completed the process must be carried out with the high-tension cords attached to the distributor cap Distributor cap/rotor arm Distributor caps can break down due to cracks within the cap itself This is very hard to diagnose visually so a substitute cap usually needs to be fitted to eliminate the cap from the diagnostic process Other problems relating to the distributor cap are fouling or wear of the side electrodes As the side electrodes wear then the air gap between the side electrode and the rotor arm increases and this will cause a reduction in secondary current leading to engine misfire -23Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue The rotor arm, as with the distributor cap, is very hard to diagnose visually so a substitute unit is normally required Wear of the rotor arm will have the same effect as wear on the side electrode of the distributor cap so a misfire of the engine will occur Contact breaker points adjustment As with the spark plugs, adjusting the breaker points is a relatively easy task that needs to be carried out during routine maintenance There are two ways in which the breaker points can be adjusted and, depending on the manufacturer, one of the two methods explained below will be used Measuring the gap between the two breaker contacts is the most common method The distributor cam is rotated until the ribbing block is positioned on one of the cam lobes and the contact breaker points are open The gap needed between the two contacts must be obtained from the manufacturers’ specification A correct feeler gauge must then be selected and placed between the two contact surfaces When the feeler gauge is inserted a very small resistance should be felt, but the breaker points should not move If either of the breaker points moves or there is no resistance when inserting the feeler gauge then the breaker points should be adjusted The breaker points can be adjusted by slackening the screw or screws securing them to the breaker plate, and rotating them until the desired gap is achieved The screws should then be locked up and the breaker point gap re-checked A possible problem with this method is that fouling of the points can occur if the feeler gauge used is not perfectly clean -24Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue The second method eliminates this problem by measuring the gap between the rubbing block and the distributor cam This time the distributor cam is rotated until the flat side of the cam is in line with the rubbing block and the contact breaker points are closed A feeler gauge is used to measure the clearance between the rubbing block and the distributor cam Manufacturers’ specifications must be referenced for rubbing block clearance If the clearance is incorrect then adjustment must be carried out as in the previous method, but using the rubbing block clearance as a reference point Vacuum and governor advancer tests In order to test the vacuum advancer a vacuum pump will be required The vacuum hose connected to the distributor must be removed and the vacuum pump connected in its place Vacuum must then be applied to the vacuum advancer and a visual check that the advancer moves carried out When the vacuum is removed then the advancer should return to its original position The governor advance check is easy to carry out and requires no special equipment The rotor arm must be turned anti-clockwise by hand and then released, it should return quickly to it original position While carrying out this check the rotor should be checked to see how it is secured to the distributor cam If it is loose then it should be replaced While checking the governor and vacuum advancer, if faults are found then the units must be replaced or repaired -25Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Battery test – 8v Battery performance can also affect the ignition system When the engine is cranked the voltage across the battery terminals should not drop below eight volts If the battery does drop below eight volts then the current travelling through the primary coil will be insufficient, as a result the secondary voltage will also be insufficient resulting in non-starting of the vehicle To test for low battery voltage, place a voltmeter across the positive and negative terminals of the battery and crank the engine using the starter motor If the voltage displayed by the voltmeter drops below eight volts then replace the battery -26Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue ... Reserved LV22: Ignition Systems (2) Issue 19 19 21 23 24 25 26 -2Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Introduction Conventional ignition systems. .. Reserved LV22: Ignition Systems (2) Issue Dwell Period and Current Limiting Ignition coil 0.5 ohms Current limiting is used with many electronic ignition systems Contact breaker ignition systems. .. systems and direct ignition systems -17Copyright © Automotive Skills Limited 2003 All Rights Reserved LV22: Ignition Systems (2) Issue Distributor-less or wasted spark ignition systems use an individual