Transcript Ignition Systems II

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
Represents #1 cylinder
Represents each cylinder
• Two sensors in one
Distributorless Ignition
Systems
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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
•One coil per two cylinders
#4
Exhaust
Stroke
#1
Comp.
Stroke
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