Detonation/Spark Knock

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Inspection	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	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Inspect the engine control system grounds for being clean, tight, and in the correct locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Ensure the resistance between the engine control module (ECM) housing and the battery negative cable is less than 0.5 ohms. Verify that the ECM and ECM bracket fasteners are at the correct torque. If the scan tool readings are normal and there are not any engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicle's minimum octane requirements. 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 restricted fuel filter. 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 the items that can cause an engine to run lean. For a lean condition, refer to DTC P2177 or DTC P2187 .
Sensor/System	Use a scan tool to monitor the knock sensor (KS) system. Refer to Knock Sensor (KS) System Description .
Ignition System	Ensure that the spark plugs are 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 Refer to the following procedures in Engine Cooling: Draining and Filling Cooling System Engine Overheating
Engine Mechanical	Inspect for the following engine mechanical conditions: Excessive oil in combustion chambers and for leaking valve seals. High cylinder compression. Incorrect camshaft timing. Excessive carbon buildup in the combustion chambers. Clean the chambers using top engine cleaner. Follow the instructions on the can. For more information, refer to the following procedures in Engine Mechanical - 3.6L (LY7): Oil Consumption Diagnosis Engine Compression Test Camshaft Timing Drive Chain Alignment Diagram Setting Camshaft Timing Symptoms - Engine Mechanical Inspect the following components for incorrect basic engine parts: Camshafts Cylinder heads Pistons, connecting rods or bearings. Refer to the following procedures in Engine Mechanical - 3.6L (LY7): Camshaft Timing Drive Components Cleaning and Inspection Camshaft Cleaning and Inspection Cylinder Head Cleaning and Inspection Piston, Connecting Rod, and Bearings Cleaning and Inspection
Additional	Test the transmission torque converter clutch (TCC) for the correct operation. Applying the TCC too soon can cause the engine to spark knock. Refer to Torque Converter Diagnosis Procedure in Automatic Transaxle - 4T65-E.