| DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. This condition is not normally felt above 1,500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or low speed. |
| Preliminary |
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| Fuel Systems |
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| Sensor/System |
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| Ignition System |
- In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:
- Inspect for proper secondary ignition voltage output with J 26792
HEI Spark Tester. See Special Tools
.
- An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.
- If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.
- Inspect for damaged or misaligned spark plug boots.
- Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300
.
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| Engine Mechanical |
- Inspect engine mechanical for the following:
- For incorrect, worn, or damaged basic engine parts, inspect the following:
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| Additional Inspections |
- Inspect the exhaust system for possible restrictions. Inspect for the following:
- Inspect the exhaust system for damaged or collapsed pipes.
- Inspect the mufflers for heat distress or possible internal failure.
- Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust
in Engine Exhaust.
- Electromagnetic interference (EMI) can cause an engine misfire condition. A sudden increase in indicated RPM parameter with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control circuits if a condition exists.
- Inspect the intake manifold and the exhaust manifold passages for casting flash.
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