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	Perform the Diagnostic System Check - Vehicle in Vehicle DTC Information Refer to Important Preliminary Checks Before Starting. Refer to Visual/Physical Checks. Search for bulletins.
Fuel System	Test for low 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 items that can cause an engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 .
Ignition System	Inspect the spark plugs for proper heat range and reach.
Engine Cooling System	Inspect for obvious overheating conditions: Low engine coolant. Refer to Loss of Coolant in Engine Cooling. Restricted air flow to radiator, or restricted water flow through radiator Inoperative electric cooling fan circuits. Refer to Cooling Fan Inoperative in Engine Cooling. Correct coolant solution. Refer to Draining and Filling Cooling System in Engine Cooling.
Engine Mechanical	Excessive oil in combustion chamber-Leaking valve seals Low cylinder compression 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.
Additional	Test for proper exhaust gas recirculation (EGR) system operation. Refer to Exhaust Gas Recirculation (EGR) System Description . 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.