Cuts Out, Misses
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Cuts Out, Misses
| Inspections |
Action |
| 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 System |
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| Sensor/System |
Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. An extended travel brake switch that is mis-adjusted or an extended travel brake circuit that is open causes a perceived misfire under heavy load conditions from a stop. Use a scan tool in order to monitor the Extended Travel Brake Switch parameter. |
| Ignition System |
Refer to Spark Plug Inspection
and Ignition System Specifications
.
- Determine the cause of the fouling before replacing the spark plugs.
- Visually and physically inspect the secondary ignition for the following:
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| Engine Mechanical |
- Inspect engine mechanical for the following:
- Inspect compression-Refer to Engine Compression Test
in Engine Mechanical.
- 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. Refer to Oil Consumption Diagnosis
in Engine Mechanical.
- For incorrect, worn or damaged basic engine parts inspect the following:
- Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearings Cleaning and Inspection
in Engine Mechanical. This could result in any of the following conditions:
- A no start
- A start and stall
- Erratic performance
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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) on the reference circuit can cause an engine misfire condition. A sudden increase in indicated RPM 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. Refer to Intake Manifold Cleaning and Inspection
or Exhaust Manifold Cleaning and Inspection
in Engine Mechanical.
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