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 changes with throttle opening.
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Preliminary Inspections
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• | 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 heated oxygen sensor (HO2S) connector |
- | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
in Engine Exhaust. |
- | Vacuum hoses that are split, kinked, or improperly connected |
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Sensor/System
| Inspect for an engine coolant temperature (ECT) sensor that has shifted in value. Refer to
Temperature Versus Resistance
.
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Ignition System
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• | Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied. |
• | Remove the spark plugs and inspect for the following conditions: |
• | Determine the cause of the fouling before replacing the spark plugs. |
• | Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. |
• | Inspect for loose ignition coil ground. |
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Engine Cooling System
| Inspect for obvious overheating conditions:
• | Restricted air flow to the radiator or restricted coolant flow through the radiator |
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Engine Mechanical
| Inspect for the following engine mechanical conditions:
• | 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 components: |
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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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