View
375
Download
16
Category
Tags:
Preview:
Citation preview
IGNITION SYSTEM SERVICE
Ignition primary service. Ignition secondary service. Ignition timing and advance. Ignition oscilloscope testing.
Ignition Systems
Types of ignition systems:- Coil Over (late 90’s and on)
- Direct Ignition (Mid 80’s and on)
- Electronic w/distributor (1975- Present)
- Breaker point (1974 and older)
Coil Over Ignition Each spark plug
has its own coil. No secondary
wiring at all. PCM triggers each
coil like a fuel injector.
Direct Ignition No Distributor One Coil for Two
Cylinders Waste Spark
System One Plug Fires
Backwards
Electronic Ignition W/Distributor
Uses one coil for all cylinders.
Distributor times out the sparks to the appropriate cylinder.
Still the most common type.
Breaker Point Ignition Very old type but
there’s still a few around.
Must replace the points every year.
The timing changes as the points wear out.
How an Ignition Coil Works All coils have two windings called the
primary and the secondary. A magnetic field is created in the primary
by current flow. When the current is shut OFF to the
primary, the magnetic field collapses across the secondary winding causing current flow.
Because the secondary has a greater number of windings, the voltage increases from 12 to 20,000 volts!
Ignition System Operation
Battery
Keyswitch
Coil ModulePick-upcoil
Collapse
Ignition Wiring
Module Function
Electro-mechanical Switch Relay
Solid-State Electronic Switch Transistor
Pick-up CoilsThe pick-up assembly tells the module when to fire the coil.
It can be mounted in one of five different locations: #1 Distributor #2 Vibration Damper #3 Flywheel #4 Crankshaft #5 Camshaft
GM V6 Crank Position Sensor CKP
Magnetic Type IgnitionPick-up
Uses an electro-magnetic and a timing disc.
The transistor turns off the primary current and fires the coil when the tooth of the timing disk lines up with the electro-magnet
Hall Effect Type Ignition Pick-up
This type of pick-up uses a semi-conductor material and blocking blade. The electrical polarity changes when the blade lines up with the semi-
conductor material. This is the signal to cause the transistor to switch off and fire the coil.
Diagnosis of the Primary Circuit Faults in the primary ignition circuit
usually result in a no start condition. Since the primary circuit is
responsible for creating the spark and timing it to the cylinder, faults can also include poor performance on cars which need to be timed.
Primary Circuit Tests
#1 Test the ignition system for function. Test at the spark plug.
#2 Test spark at the ignition coil. #3 Test the feed circuit from the battery
to the coil. #4 Test the ignition coil windings. #5 Test the pick-up coil. #6 Test the pick-up unit with a lab scope.
Ignition Secondary CircuitService Spark plug service Distributor cap & rotor Spark plug wires
Spark Plug Service Look up proper
application and gap.
Proper removal. Installation tricks. Firing order! Heat range.
Spark Plug Heat RangeSpark Plug Heat Range
HHeat range has nothing HHeat range has nothing to do with the spark but to do with the spark but with the physical with the physical temperature of the plug temperature of the plug electrodes.electrodes.FWith very short trip FWith very short trip driving an engine needs a driving an engine needs a HOTHOT plug. plug.FWith extensive highway FWith extensive highway driving an engine needs a driving an engine needs a COLDCOLD plug. plug.
Checking Plug Wires Visual inspection Ohmmeter Firing order
Cap and Rotor Service Inspection Check for: Burnt center
button Cracks Burns and carbon
tracking Corrosion
Ignition Timing Manual timing. Mechanical or centrifugal advance. Vacuum advance. Computer controlled timing
advance.
Definition of Ignition Timing The plug fires when the pick-up coil
or crankshaft sensor detects the piston to be in the proper position for combustion. It tells the module to shut off primary current to the ignition coil and the magnetic field collapses firing the spark plug.
Setting Basic Ignition Timing
Methods: Static Using a timing
light. Using a magnetic
timing device.
Why Timing Needs to be Advanced.
Using the Oscilloscope What does the oscilloscope
measure?
VOLTAGE
TIME
Engine Analyzer
These machines contain amulti-function oscilloscope which can be used for the following:-Ignition patterns.-PCM sensor and actuator patterns.
Big Bucks!
We Have 3 Oscilloscopes Old Sun 1160 analog machine. Bear Ace digital scope. Sun 450 the latest in technology.
How is the Scope Hooked Up?
Engines with distributors:One connection is made to the coil wire.One connection is made to the #1 plug wire.
On Direct Ignition Engines:A connection must be made to each plug wire.
On Coil Over Ignitions:Only a primary waveform can be generated offThe negative side of the coil primary.
Secondary Waveform
Ways to View the Secondary Waveform Parade or display Raster Superimposed
Recommended