For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: A steady pulsation or jerking that follows engine speed, which is usually more pronounced as the engine load increases. This condition is not normally felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or at low speed.
Preliminary |

• | Refer to Important Preliminary Inspections Before Starting in Symptoms .

• | Search for bulletins.

• | Inspect the ECM grounds for being clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

• | Inspect the intake AIR ducts for leaks and proper location.

• | Remove the air filter element and inspect for dirt or for being restricted. Refer to Air Filter Element and Air Cleaner Assembly . Replace if necessary.

Fuel System |

• | Test the fuel injectors. Refer to Fuel Injector Solenoid Coil Test .

• | Test for proper fuel pressure. Refer to Fuel System Diagnosis .

• | Test for a restricted fuel filter. Refer to Fuel System Diagnosis .

• | Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• | Inspect the items which can cause an engine to run rich (long term fuel trim near -13 percent). For a rich condition, refer to DTC P0172 Fuel Trim System Rich Bank 1 and DTC P0175 Fuel Trim System Rich Bank 2 .

• | Inspect items that can cause an engine to run lean (long term fuel trim near 23 percent). For a lean condition, refer to DTC P0171 Fuel Trim System Lean Bank 1 and DTC P0174 Fuel Trim System Lean Bank 2 .

Sensor/System |

• | Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Detonation/Spark Knock .

• | Inspect the CKP sensor for proper operation or intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Ignition System |

• | Test for proper ignition voltage output with a J 26792 spark tester. Refer to Ignition System Check .

• | Test for secondary ignition system leakage. Perform the procedure in the Diagnostic Aids portion of the Ignition System Check .

• | Remove the spark plugs and inspect for the following conditions:

- | Correct heat range

- | Wet plugs

- | Cracks

- | Wear

- | Improper gap

- | Burned electrodes

- | Heavy deposits

• | An improper spark plug gap may cause a driveability concern. Gap the spark plugs using a wire gauge gap tool. Refer to Spark Plug Replacement in Engine Electrical.

• | Determine the cause of the fouling before replacing the spark plugs if the spark plugs are gas, coolant or oil fouled. Refer to Spark Plug Visual Diagnosis in Engine Electrical.

- | For diagnosis of the rich condition, refer to DTC P0172 Fuel Trim System Rich Bank 1 or DTC P0175 Fuel Trim System Rich Bank 2 .

- | For diagnosis of coolant contaminated spark plugs, refer to Loss of Coolant in Engine Cooling.

- | For diagnosis of oil fouled spark plugs, refer to Oil Consumption Diagnosis in Engine Mechanical.

Engine Mechanical |

• | Inspect engine mechanical for the following:

- | Test compression

- | Sticking or leaking valves

- | Worn camshaft lobes

- | Camshaft timing

- | Broken valve springs

- | Excessive oil in combustion chamber-Leaking valve seals

• | For more information, refer to one or more of the following procedures in Engine Mechanical:

- | Engine Compression Test

- | Timing Belt Timing Adjustment

- | Oil Consumption Diagnosis

• | For incorrect basic engine parts, inspect the following components:

- | Camshafts

- | Cylinder heads

- | Pistons, etc.

• | Refer to Engine Mechanical for diagnosis procedures.

Additional Checks |

• | Inspect the following exhaust system components for possible restrictions:

- | The exhaust system for physical damage

- | The mufflers for heat distress or possible internal failure

- | The catalytic converters for possible plugged pipes by comparing the exhaust system back pressure on each side of engine. Refer to Restricted Exhaust System Check .

• | Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI may be present. Inspect for high voltage components near the ignition control circuits if a condition exists.

• | Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Replacement or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.