For 1990-2009 cars

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 |

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

• | Search for bulletins.

• | Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views and Engine Controls Schematics .

• | Remove the air filter element and inspect for dirt and for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.

Sensor/System |

• | Test the fuel injectors. Refer to Fuel Injector Diagnosis .

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

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

• | Inspect for the following conditions that may cause the engine to run rich:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

- | Any water intrusion in the heated oxygen sensor (HO2S) connector

- | The engine oil contaminated by fuel

- | Incorrect fuel pressure--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

- | Any leaking fuel injectors--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

- | Any vacuum hoses that are split, kinked, or improperly connected

- | An air intake duct that is collapsed or restricted--Refer to Air Cleaner Inlet Duct Replacement .

- | An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .

• | Inspect for the following conditions that may cause the engine to run lean:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

- | Any water intrusion in the HO2S connector

- | An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage .

- | Any vacuum leaks

- | Incorrect fuel pressure--Refer to Fuel System Diagnosis .

- | Any restricted fuel injectors--Refer to Fuel Injector Diagnosis .

- | Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

- | Any vacuum hoses that are split, kinked, or improperly connected

• | Inspect for throttle body tampering, excessive deposits, or damage.

• | Inspect the crankcase ventilation system for proper operation. Refer to Crankcase Ventilation System Inspection/Diagnosis .

Ignition System |

• | In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:

- | Ignition System Specifications

- | Spark Plug Inspection

- | Spark Plug Replacement

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

- | Correct heat range

- | Wet plugs

- | Cracks

- | Wear

- | Improper gap

- | Burned electrodes

- | Heavy deposits

- | Verify that the spark plugs are of the correct type.

• | Inspect for proper ignition system output. Refer to Electronic Ignition (EI) System Diagnosis .

• | An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.

• | Determine the cause of the fouling before replacing the spark plugs.

• | Inspect for damaged or misaligned spark plug boots.

• | Inspect the electronic ignition (EI) module for proper ground connection.

• | 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 .

Engine Mechanical |

• | Inspect engine mechanical for the following conditions:

- | Compression

- | Sticking or leaking valves

- | Worn camshaft lobes

- | Valve timing

- | Worn rocker arms

- | Broken valve springs

- | Excessive oil in combustion chamber or leaking valve seals.

- | For more information, refer to one or more of the following procedures.

• | Engine Compression Test

• | Symptoms - Engine Mechanical

• | Oil Consumption Diagnosis

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

- | The camshaft--Refer to Camshaft Cleaning and Inspection .

- | The cylinder heads--Refer to Cylinder Head Cleaning and Inspection .

- | The pistons, etc.--Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection .

• | Refer to Symptoms - Engine Mechanical for diagnosis procedures.

• | 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 Camshaft Cleaning and Inspection . This could result in any of the following conditions:

- | A no start

- | A start and stall

- | Erratic performance

Additional Inspections |

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

- | The exhaust system for damaged or collapsed pipes

- | The mufflers for heat distress or possible internal failure

- | The catalytic converters for being plugged--Refer to Restricted Exhaust .

• | Electromagnetic interference (EMI) 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.