Checks
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DEFINITION: A steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases. The exhaust has a steady spitting sound at idle, low speed or on hard acceleration.
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Preliminary Checks
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Ignition System Checks
| Check for an ignition system misfire:
Important: DO NOT perform this test for more than 2 minutes in order to prevent damage to the catalytic converter.
- Start the engine.
- Remove one spark plug wire at a time with insulated pliers.
- An equal RPM drop on all cylinders (within 50 RPM) indicates a common condition. Refer to
Rough, Unstable, or Incorrect Idle and Stalling .
- No RPM drop on one or more cylinders indicates a cylinder specific condition. Check for spark on the suspected cylinder(s) with a
J 26792 spark tester or equivalent.
- If there is no spark, Refer to
Engine Cranks But Does Not Run .
- If there is spark, check the spark plugs for any of the following conditions:
| - | Wet (fuel fouled) plugs. |
| - | A terminal screw that is bent or loose (rotate and pull). |
| - | A ceramic insulator that has cracks, carbon tracking or deposits (red or black dust) |
| - | A tip insulator that has cracks, carbon tracking, deposits (oil, carbon, glazing, fuel additive), or is loose (rattles). |
| - | A center electrode that is loose (wiggles side to side) |
| - | An incorrect spark plug gap that is too large or too small. |
| - | Platinum pads that are missing. |
| • | Check that the spark plug wire resistance does not exceed 30,000 ohms. |
| • | Check the distributor cap and the distributor rotor. |
| • | Check the ignition system for moisture, dust, cracks, burns, etc. |
| • | Run the engine and spray the secondary ignition system with water in order to check for secondary voltage shorts. |
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Engine Mechanical Checks
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| • | Check for any of the following engine mechanical problems: |
| - | Faulty hydraulic lifter assemblies |
| - | Broken or weak valve springs |
| - | Incorrect or worn camshaft |
| • | Check the intake and exhaust manifold passages for casting flash. |
| • | Refer to Engine Mechanical. |
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Fuel System Checks
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| • | Check for a restricted fuel filter. |
| • | Check the fuel injector solenoid for sticking, erratic operation. |
| • | Check for water contamination of the fuel. |
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Additional Checks
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| • | Check the PCM grounds for being clean, tight, and in their proper locations. Refer to PCM Power and Ground electrical schematic. |
| • | Check the Service Bulletins for any updates or information. |
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