Detonation/Spark Knock

Inspection/Test	Action
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
Preliminary	Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls . Search for bulletins.
Fuel System	Test the fuel pressure. Refer to Fuel System Diagnosis . Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (With Special Tool) . Inspect the following that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Any water intrusion into the HO2S connector. An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Any vacuum leaks. Incorrect fuel pressure-Refer to Fuel System Diagnosis . Any lean fuel injectors-Refer to Fuel Injector Balance Test with Tech 2 and Fuel Injector Balance Test with Special Tool . An inaccurate mass air flow (MAF) sensor. Fuel Contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (With Special Tool) . Vacuum hoses for splits, kinks and proper connections.
Ignition System	Inspect the spark plugs. Refer to Spark Plug Inspection
Engine Cooling System	Inspect for causes of overheating: Low engine coolant level. Refer to Loss of Coolant in Engine Cooling. Restricted air flow to radiator, or restricted coolant flow through the radiator. Refer to Engine Overheating in Engine Cooling. Insufficient cooling fan operation. Refer to Cooling Fan Inoperative in Engine Cooling.
Engine Mechanical	Inspect for excessive oil in the combustion chamber-leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical. Engine compression-Refer to Engine Compression Test in Engine Mechanical. Inspect the combustion chamber for excessive carbon buildup. Clean using Top Engine Cleaner. Follow instructions on can. Inspect the following for incorrect basic engine parts: Camshafts Cylinder heads Pistons, etc.
Additional	Inspect the torque converter clutch (TCC) system for proper operation. Refer to Torque Converter Diagnosis Procedure in Automatic Transaxle. If the scan tool readings are normal, and there are no engine mechanical faults, fill the fuel tank with a premium gasoline that has a minimum octane reading of 92 and re-evaluate the vehicle.