| DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening. |
| Preliminary Inspections |
- Perform the Diagnostic System Check - Vehicle
in Vehicle DTC Information
- 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
in Wiring Systems.
- 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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| Ignition System |
Inspect the spark plugs for proper heat range and reach. |
| Engine Cooling System |
Inspect for obvious overheating conditions:
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| Engine Mechanical |
- Excessive oil in combustion chamber-Leaking valve seals-Refer to Oil Consumption Diagnosis
in Engine Mechanical - 3.8L.
- Low cylinder compression-Refer to Engine Compression Test
in Engine Mechanical - 3.8L.
- Combustion chambers for excessive carbon buildup-Clean using top engine cleaner. Follow instructions on can.
- For incorrect basic engine parts-Inspect the following:
- Camshaft
- Cylinder heads
- Pistons, etc.
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| Additional Inspections |
- Test for proper exhaust gas recirculation (EGR) system operation. Refer to DTC P0401
.
- Inspect the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive.
- Test torque converter clutch (TCC) operation. TCC applying too soon can cause the engine to spark knock. Refer to Torque Converter Diagnosis Procedure
in Automatic Transaxle - 4T65-E.
- If scan tool readings are normal and there are no engine mechanical faults, fill the fuel tank with a known quality gasoline that has a minimum octane reading of 87 and re-evaluate vehicle performance.
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