Detonation/Spark Knock

WARNING: This page is about a different variant/trim than selected.

Inspection/Tests	Action
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. Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems 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 vehicles performance.
Fuel System	Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) . Inspect the fuel injectors. Refer to Fuel Injector Coil Test . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. 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 leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 . Manifold absolute pressure (MAP) sensor operation-Refer to DTC P0106 . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Ignition System	Verify that the spark plugs are of the proper heat range. Refer to Spark Plug Inspection .
Engine Cooling System	Inspect for obvious overheating problems: Low engine coolant-Refer to Loss of Coolant (M 35) or Loss of Coolant (M 82) in Engine Cooling for the type and amount of engine coolant to be used. Restricted air flow to the radiator or restricted coolant flow through the radiator. Proper tension on the drive belts-Refer to Drive Belt Tensioner Diagnosis . Inoperative cooling fan-Refer to Cooling Fan Inoperative .
Engine Mechanical	Inspect for the following engine mechanical problems: Excessive oil in combustion chamber-Leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical. Incorrect cylinder compression-Refer to Engine Compression Test Engine Mechanical. Combustion chambers for excessive carbon buildup-Clean the combustion chamber by using top engine cleaner. Follow the instructions on the can. Inspect for incorrect, worn or damaged basic engine parts. Inspect the following: The camshaft-Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection in Engine Mechanical. Refer to Symptoms - Engine Mechanical in Engine Mechanical.