Download Automotive Ignition Systems

Automotive
Ignition Systems
Ignition System Purpose
Create a high voltage spark
 Deliver the spark at correct time
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Ignition Timing
BTDC
 ATDC
 Engine RPM
 Engine Load
 Firing Order
 Retard
 Advance
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Firing Order
Firing Order
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1,3,4,2
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1,2,5,4,3,2
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1,5,6,3,4,2,7,8
Firing Order
Ignition System Circuits
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Primary Circuit
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(Low Voltage)
Ignition Switch
Resistor
Coil Primary Winding
Ignition Module
Pick-up Assembly
Secondary Circuit
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(High Voltage)
Coil Secondary
Winding
Coil Wire
Distributor Cap &
Rotor
Plug Wires
Spark Plugs
Ignition Primary Circuit
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Battery
Ignition Switch
Resistor
Coil Winding
Ignition Module
Pick-up Assembly
Low voltage side
Ignition Coils
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Step-up transformer
Primary winding
Secondary winding
Uses electromagnetic induction
to operate
Magnetic field must
be built up and then
collapsed
Ignition Coil
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High Voltage wire
+ Battery
- ign module
Primary Windings
Secondary Windings
Making & Breaking Fields
Ignition Modules
Old Systems Used
Breaker Points
 Modules Contain a
Switching Transistor
 Externally Mounted
 Distributor Mounted
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Ignition Pick-up
Assemblies
Can be mounted in one of
five different locations:
#1
#2
#3
#4
#5
Distributor
Vibration Damper
Flywheel
Crankshaft
Camshaft
Distributor
A mechanical timing
device
 Drives off engine
camshaft
 Can controls both
primary and
secondary circuits
 May contain
advance units
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The Rotor at Work
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Rotates around to
DISTRIBUTE voltage
to each spark plug
http://www.hows
tuffworks.com/igni
tion-system4.htm
Ignition Secondary Circuit
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Coil Winding
Coil Wire
Distributor Cap &
Rotor
Spark Plug Wire
Spark Plug
Distributor Cap & Rotor
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Cap fits on top of the
distributor housing
Made of lexon plastic
Has an index mark for
proper installation
Rotor fits on top of
distributor shaft
Also is indexed
Spark Plug Wires
Very high resistance
wire 1000 ohms per
inch
 Mostly insulation
material
 Small conductor
material
 Must follow firing
order
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Spark Plug Placement
Spark Plugs
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Shell w/threads
Ceramic insulator
Center electrode
Side electrode
Plug gap
Heat range
Plug designation
Resistor Plugs
Heat Rages of Plugs
The difference
between a "hot" and
a "cold" spark plug
is in the shape of the
ceramic tip.
The difference between a "hot" and a "cold" spark plug is in the shape of the ceramtip.
The carmaker will select the right-temperature plug for each car.
Some cars with high-performance engines naturally generate
more heat, so they need colder plugs. If the spark plug gets too
hot, it could ignite the fuel before the spark fires; so it is important
to stick with the right type of plug for your car.
Spark Plugs tell a story
Normal
Over Heating
Worn
Carbon
Lead Erossion
Fuel/Additive
Deposits
Insulator Breakage
Lead Fouled
Lead Fouled
Minor Melting
Oil
Old Breaker Point Ignition
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Used 1920’s - 1974
mechanical switch in
distributor
build-up - collapse
coil magnetic field
Points wear out
Must be replaced
each year
Breaker Point (dwell angle)
Breaker Point Parts
Making & Collapsing field
Electronic Ignition with
Distributor (HEI)
1970’s
 Transistor in ignition
module turns coil
on/ off
 Module mounted
externally or in
distributor
 Pick-up in distributor
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High Energy Ignition (HEI)
Trigger Wheel
No Points
 Rotating Reluctor
Wheel
 Fewer Tune-Ups
 More Efficient
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Optical Trigger (Chrysler)
Photo Electric
Sensor
 (Photo = Light)
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CKPS (crankshaft position sensor)
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Fewer Parts
No Points
No Distributor
No Rotor
Computer Controlled
More Efficient
Crank Trigger Wheel
Direct Ignition
No Distributor
 One Coil for Two
Cylinders
 Waste Spark System
 One Plug Fires
Backwards
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Wasted Spark
1st plug fires
forward
 2nd fires backwards
 Sister cylinders
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Direct Ignition
Coil Over
Business End of the Ignition
System
Size
 Reach
 Heat Range
 Spark.Air Gap
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Ignition System
Maintenance
Replace Spark Plugs every
30,000mi/36mo
 Inspect Cap and Rotor (replace if
necessary)
 Inspect Spark Plug wires (replace if
necessary)
 Check Firing Order
 Check Ignition Timing (if necessary)
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Timing
Engine Warm
 At Idle
 Defeat Advance
 #1 Plug wire
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