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DIS SYSTEMS. Ignition Function. Hot spark across spark plug gap Distributes high voltage to each plug in correct sequence Time the spark so it arrives as piston nearing TDC Adjusts spark timing with load & speed. Electronic Ignition Systems.
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Ignition Function • Hot spark across spark plug gap • Distributes high voltage to each plug in correct sequence • Time the spark so it arrives as piston nearing TDC • Adjusts spark timing with load & speed
Electronic Ignition Systems • Uses electronic control circuit to fire ignition coil • More dependable than contact system • Higher secondary ignition voltages
Magnetic Pickup Coil • Produces tiny voltage pulses as magnetic field changes • Trigger Wheel interrupts magnetic field • Signals control unit to fire coil
Computer Controlled Ignition Systems • Produce maximum engine power & fuel efficiency, reduced tailpipe emissions • Ignition spark timing is continuously and accurately adjusted
Magnetic Pulse Generator • Wire wrapped around a weak magnet, timing disk mounted to the crank or cam shaft. Disk has points or windows that interrupt the magnetic field. AC voltage induced is sent to control module to fire coil.
Hall-Effect Sensor • Works similar to MPG • Voltage generated at all times • Rotating shutters interrupt the voltage, turning off the voltage • Schmitt trigger cleans up the signal & converts it to a square wave (digital) signal
Crankshaft Sensor (CKP) Measures crankshaft RPM
Dual Crankshaft Sensor • Two sensors in one Represents #1 cylinder Represents each cylinder
Distributorless Ignition Systems • No Distributor • One coil per two cylinders (waist spark) • One coil per cylinder (coil over plug) • Ignition Module synchronizes the firing sequence in relation to crankshaft position • Ignition module signals ECM when to control each fuel injector • Ignition module provides tachometer signal
Waist Spark • One coil per two cylinders #4 Exhaust Stroke #1 Comp. Stroke
GM’s C3 Ignition System Ignition Control Module
Knock Sensor • Mounted in engine block • Detects preignition and detonation • Vibrations create a small AC voltage which is sent to ignition module or ECM • Computer determines if voltages are frequent enough, if so, timing is retarded