| DEFINITION: Fuel ignites in the intake manifold, or in the exhaust system, making loud popping noise. |
| Preliminary |
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| Sensor/System |
- Inspect for the following intermittent ignition system conditions:
- Monitor the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Test all CKP sensor A and CMP sensor circuits for intermittents. Refer to Testing for Intermittent Conditions and Poor Connections
in Wiring Systems.
- Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the CKP sensor B and circuits for intermittents. Inspect the ignition control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a diagnostic trouble code (DTC) immediately, but are capable of causing driveability complaints. Refer to Testing for Intermittent Conditions and Poor Connections
in Wiring Systems.
- Test the CKP sensor B for an internal short. Refer to Electronic Ignition (EI) System Diagnosis .
- Inspect the mass air flow (MAF) sensor conditions. Ensure that the MAF sensor honeycomb is not damaged.
|
| Fuel System |
|
| Ignition System |
- Inspect for proper ignition voltage output using the following steps:
- Attach the J 26792
Spark Tester to engine ground.
- Connect the spark plug end of the spark plug wire to the J 26792
. Leave the other end of the spark plug wire connected to the coil being tested.
- Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
- Crank the engine while observing the J 26792
. A spark should be observed.
- Repeat the above steps for each coil.
- If spark is not present at the coils, inspect for the following conditions:
- Coils-Cracks, carbon tracking/arcing, or a resistance value outside the specified range
Coil Resistance:
5000-8000 Ω (5K-8K Ω)
- Spark plug wires-Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range
Spark Plug Wire Resistance:
9 686 Ω per meter (3,000 Ω per foot)
IMPORTANT:
Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition voltage will arc to ground when a secondary component is faulty.
- Defective ignition module
- Ignition system wiring-Loose ignition module feed or ground connection, or damaged system wiring
- Remove spark plugs and inspect for the following conditions:
- Fouled plugs
- Cracks
- Wear
- Improper gap
- Burned or damaged electrodes
- Improper heat range or reach
- If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs. Refer to Spark Plug Inspection
.
|
| Engine Mechanical |
Inspect engine mechanical for the following conditions:
- Test compression
- Sticking or leaking valves
- Worn camshaft lobes
- Valve timing
- Bent push rods
- Worn rocker arms
- Broken valve springs
- Excessive oil in combustion chamber-Leaking valve seals
- Low cylinder compression
|
| Additional |
- Inspect intake and exhaust manifolds for casting flash.
- Test the torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis Procedure
in Automatic Transaxle.
- Inspect the exhaust system for possible restriction:
- Inspect exhaust system for damaged or collapsed pipes.
- Inspect mufflers for heat distress or possible internal failure.
- For possible plugged catalytic converter
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