For 1990-2009 cars

Inspection/Tests | Action
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DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
Preliminary Inspections |

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

• | Search for bulletins.

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

• | If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicles minimum octane requirements. Road test the vehicle and re-evaluate the performance of the vehicle.

Fuel System |

• | Test for incorrect fuel pressure. Refer to Fuel Pump Electrical Circuit Diagnosis .

• | Inspect for a restricted fuel filter. Refer to Fuel Pump Electrical Circuit Diagnosis .

• | Test the fuel injectors. Refer to Fuel Injector 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 lean:

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

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

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

- | Vacuum leaks

- | Incorrect fuel pressure--Refer to Fuel Pump Electrical Circuit Diagnosis .

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

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

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

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

Sensor/System | Inspect for an engine coolant temperature (ECT) sensor that has shifted in value . Refer to Temperature Versus Resistance .
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

• | Remove spark plugs and inspect for the following:

- | 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 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 gauge 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.

Engine Cooling System | Inspect for obvious overheating problems:

• | Low engine coolant--Refer to Loss of Coolant .

• | Faulty thermostat--Refer to Thermostat Diagnosis .

• | Restricted air flow to the radiator or restricted coolant flow through the radiator

• | Inoperative cooling fan--Refer to Fan Clutch Diagnosis .

• | Proper tension on the drive belts

• | Correct coolant solution should be a 50/50 mix. Refer to Cooling System Description and Operation .

Engine Mechanical | Inspect for the following engine mechanical problems:

• | Excessive oil in combustion chamber--Leaking valve seals. Refer to Oil Consumption Diagnosis .

• | High cylinder compression--Refer to Engine Compression Test .

• | Combustion chambers for excessive carbon buildup--Clean the combustion chamber by using top engine cleaner. Follow the instructions on the can.

• | Incorrect camshaft timing

• | Inspect 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 transmission torque converter clutch (TCC) operation. Refer to Symptoms - Automatic Transmission for the 4L60-E/4L65-E transmission.