For 1990-2009 cars

Checks | Action
--- | ---
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.
Preliminary Checks |

• | Refer to Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Symptoms .

Ignition System Checks | Check for an ignition system misfire:

1. Start the engine.
2. Remove one spark plug wire at a time with insulated pliers.
3. An equal RPM drop on all cylinders (within 50 RPM) indicates a common condition. Refer to Rough, Unstable, or Incorrect Idle and Stalling .
4. No RPM drop on one or more cylinders indicates a cylinder specific condition. Check for spark on the suspected cylinders with a J 26792 spark tester or equivalent.
5. If there is no spark, Refer to Engine Cranks but Does Not Run .
6. 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.

Engine Mechanical Checks |

• | Check for any of the following engine mechanical problems:

- | Faulty hydraulic lifter assemblies

- | Broken or weak valve springs

- | Incorrect valve timing

- | Incorrect or worn camshaft

• | Check the intake and exhaust manifold passages for casting flash.

• | Refer to Engine Compression Test in Engine Mechanical.

Fuel System Checks |

• | Check for a restricted fuel filter.

• | Check for the correct fuel pressure. Refer to Fuel System Diagnosis .

• | Check the fuel injector solenoid for sticking, erratic operation.

• | Check for water contamination of the fuel.

Additional Checks |

• | Check the PCM grounds for being clean, tight, and in their proper locations. Refer to Ground Distribution Schematics in Wiring Systems.

• | Check the Service Bulletins for any updates or information.