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