Detonation/Spark Knock

Checks	Action
DEFINITION: A mild to severe ping which usually occurs worse while under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
Preliminary Checks	Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls . Search for bulletins. Verify that the engine control module (ECM) grounds are clean, tight, and in the correct locations. If the scan tool readings are normal and there are no engine mechanical conditions, fill the fuel tank with a known high quality fuel that meets the vehicle's minimum octane requirements. Refer to Symptoms - Engine Controls . Road test the vehicle and re-evaluate the vehicle's performance.
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (W/O Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (W/Special Tool) . Test the fuel injectors. Refer to Fuel Injector Coil Test . Test or inspect items that can cause an engine to run lean. For a lean condition, refer to DTC P0171 .
Sensor/System	Use a scan tool to monitor the knock sensor (KS) system. Refer to Knock Sensor (KS) System Description and DTC P0327 .
Ignition System	Verify that the spark plugs are of the correct heat range. Refer to Ignition System Specifications .
Engine Cooling System	Test for obvious overheating conditions. Test or inspect for the following conditions: Low engine coolant level Incorrect engine coolant Restricted air flow to the radiator or restricted coolant flow through the radiator Engine coolant leaks Incorrect fan operation Refer to the following procedures in Engine Cooling: Draining and Filling Cooling System Engine Overheating Symptoms - Engine Cooling
Engine Mechanical	Inspect for the following engine mechanical conditions: Excessive oil in the combustion chambers and for leaking valve seals. High cylinder compression. Refer to Engine Compression Test in Engine Mechanical - 1.6L (L91). Excessive carbon buildup in the combustion chambers. Clean the chambers with top engine cleaner. Follow the instructions on the can. Inspect the following for incorrect basic engine parts: The camshaft The cylinder heads The pistons, connecting rods, and bearings Refer to the following procedures in Engine Mechanical - 1.6L (L91): Cylinder Head Replacement Camshaft Replacement Piston, Connecting Rod, and Bearings Cleaning and Inspection
Additional Checks	Test the transmission torque converter clutch (TCC). Applying the TCC too soon can cause the engine to spark knock. Refer to Symptoms - Automatic Transmission in Automatic Transmission - Aisin (81-40LE).