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 Beginning 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.

Fuel Systems |

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

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

• | Inspect for a restricted fuel filter. 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.

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

- | Purging of a saturated evaporative emission (EVAP) canister

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

- | A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .

- | Leaking fuel injectors--Refer to Fuel System Diagnosis .

- | Proper operation of the manifold absolute pressure (MAP) sensor--Refer to Altitude Versus Barometric Pressure .

- | Vacuum hoses that are split, kinked, or improperly connected

- | An air intake duct that is collapsed or restricted

- | 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.

- | Water intrusion in the HO2S connector

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

- | Vacuum leaks

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

- | Restricted fuel injectors--Refer to Fuel Injector Diagnosis .

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

- | Vacuum hoses that are split, kinked, or improperly connected

Sensor/System |

• | Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance .

• | Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data List .

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

• | Inspect the crankcase ventilation system for proper operation.

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 Replacement

- | Spark Plug Inspection

• | Inspect for proper secondary ignition voltage output with J 26792 HEI Spark Tester.

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

• | If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.

• | Inspect for damaged or misaligned spark plug boots.

• | 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:

- | 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, worn, or damaged basic engine parts, inspect the following:

- | The camshaft--Refer to Camshafts 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 .

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 .

• | Electromagnetic interference (EMI) can cause an engine misfire condition. A sudden increase in indicated RPM parameter 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.