IGNITION SYSTEM SERVICE Ignition primary service. Ignition secondary service. Ignition timing and advance. Ignition oscilloscope testing

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Slide 2 IGNITION SYSTEM SERVICE Ignition primary service. Ignition secondary service. Ignition timing and advance. Ignition oscilloscope testing. Slide 3 Ignition Systems Types of ignition systems: - Coil Over (late 90s and on) - Direct Ignition (Mid 80s and on) - Electronic w/distributor (1975- Present) - Breaker point (1974 and older) Slide 4 Coil Over Ignition Each spark plug has its own coil. No secondary wiring at all. PCM triggers each coil like a fuel injector. Slide 5 Direct Ignition No Distributor One Coil for Two Cylinders Waste Spark System One Plug Fires Backwards Slide 6 Electronic Ignition W/Distributor Uses one coil for all cylinders. Distributor times out the sparks to the appropriate cylinder. Still the most common type. Slide 7 Breaker Point Ignition Very old type but theres still a few around. Must replace the points every year. The timing changes as the points wear out. Slide 8 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! Slide 9 Ignition System Operation Battery Key switch Coil Module Pick-up coil Collapse Slide 10 Ignition Wiring Slide 11 Module Function Electro-mechanical Switch Relay Solid-State Electronic Switch Transistor Slide 12 Pick-up Coils The 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 Slide 13 GM V6 Crank Position Sensor CKP Slide 14 Magnetic Type Ignition Pick-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 Slide 15 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. Slide 16 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. Slide 17 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. Slide 18 Ignition Secondary Circuit Service Spark plug service Distributor cap & rotor Spark plug wires Slide 19 Spark Plug Service Look up proper application and gap. Proper removal. Installation tricks. Firing order! Heat range. Slide 20 Spark Plug Heat Range HHeat range has nothing to do with the spark but with the physical temperature of the plug electrodes. HHeat range has nothing to do with the spark but with the physical temperature of the plug electrodes. FWith very short trip driving an engine needs a HOT plug. FWith very short trip driving an engine needs a HOT plug. FWith extensive highway driving an engine needs a COLD plug. FWith extensive highway driving an engine needs a COLD plug. Slide 21 Checking Plug Wires Visual inspection Ohmmeter Firing order Slide 22 Cap and Rotor Service Inspection Check for: Burnt center button Cracks Burns and carbon tracking Corrosion Slide 23 Ignition Timing Manual timing. Mechanical or centrifugal advance. Vacuum advance. Computer controlled timing advance. Slide 24 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. Slide 25 Setting Basic Ignition Timing Methods: Static Using a timing light. Using a magnetic timing device. Slide 26 Why Timing Needs to be Advanced. Slide 27 Using the Oscilloscope What does the oscilloscope measure? V O L T A G E TIME Slide 28 Engine Analyzer These machines contain a multi-function oscilloscope which can be used for the following: -Ignition patterns. -PCM sensor and actuator patterns. Big Bucks! Slide 29 We Have 3 Oscilloscopes Old Sun 1160 analog machine. Bear Ace digital scope. Sun 450 the latest in technology. Slide 30 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 off The negative side of the coil primary. Slide 31 Secondary Waveform Slide 32 Ways to View the Secondary Waveform Parade or display Raster Superimposed