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

• 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.

MP Generator Waveform

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

Cylinder Arraignment

Waist Spark

#4

Exhaust

Stroke

#1

Comp.

Stroke

•One coil per two cylinders

Coil Over Plug

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