Detonation/Spark Knock
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.
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Preliminary Inspections
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• | Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. |
• | 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 vehicles performance. |
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Fuel System
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• | 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. |
- | An inaccurate MAF sensor |
- | Vacuum hoses that are split, kinked, or improperly connected |
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Ignition System
| Verify that the spark plugs are of the proper heat range. Refer to
Spark Plug Inspection
.
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Engine
Cooling System
| Inspect for obvious overheating problems:
• | Restricted air flow to the radiator or restricted coolant flow through the radiator. |
• | Inoperative cooling fan. |
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Engine
Mechanical
| Inspect for the following engine mechanical problems:
• | Combustion chambers for excessive carbon buildup--Clean the combustion chamber by using top engine cleaner. Follow the instructions on the can. |
• | Inspect for incorrect basic engine parts. Inspect the following: |
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Additional Inspections
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• | Inspect the park/neutral position (PNP) switch operation. |
• | Inspect the transmission torque converter clutch (TCC) operation. The TCC applying too soon can cause the engine to spark knock. |
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