Chart C-4 Ignition Misfire Check

Chart C-4 - Misfire:

Ignition Coil Assembly Wiring Circuit:

Circuit Description:
The Electronic Ignition (El) system uses a waste spark method of distribution. In this type of system, the ignition coil assembly triggers the #1/4 coil pair resulting in both #1 and #4 spark plugs firing at the same time. #1 cylinder is on the compression stroke at the same time #4 is on the exhaust stroke, resulting in a lower energy requirement to fire #4 spark plug. This leaves the remainder of the high voltage to be used to fire #1 spark plug. On this application, the Crankshaft Position (CKP) sensor is mounted to the engine block and protrudes through the block to within approximately .050 inch of the crankshaft reluctor. Since the reluctor is a machined portion of the crankshaft and the Crankshaft Position (CKP) sensor is mounted in a fixed position on the block, timing adjustments are not possible or necessary.

Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
1. The Electronic Ignition (El) system uses two plugs and cables to complete the circuit of each coil. The companion cylinder spark plug cable in the circuit must be connected to a good ground to create a spark. Test each spark plug cable with the engine idling (the ignition must be cycled "OFF" when moving the ST-125 tester to a different spark plug cable).
^ Keep disconnected spark plug leads away from sensors and other electronic components.
^ Move quickly through this test. Don't leave any spark plug lead disconnected for longer than 15 seconds.
^ Let the engine run normally for 30 seconds between tests to avoid an excessive buildup of fuel.
2. The test light should flash, indicating that the ECM is controlling the injector(s). How bright the light flashes is not important.
3. Nominal voltage reading of each injector should be 5.7 - 6.6 volts at 100 - 35°C (500 - 95°F). To check the mechanical (fuel delivery) portion of the fuel injector, perform injector balance test.
4. The spark plug cables should be measured with a ohmmeter for correct resistance (each wire should be less than 30,000 ohms).
5. Damage to the ECM injector driver may occur if injector driver CKT 467 or CKT 468 shorts to ignition CKT 439.