Detonation/Spark Knock

If engine exhibits a mild-to-severe ping or knock (usually worse under acceleration) as throttle position changes, check the following items:

• Perform VISUAL/PHYSICAL INSPECTION  .
• Check for contaminated or poor quality fuel. Replace fuel with 92 octane rated fuel and revaluate vehicle performance.
• Check fuel pressure.
• Ensure ignition timing and controls are working properly.
• Ensure spark plug application and gap is correct.
• Check ignition wires for shorts, bad insulation, misfiring, crossfiring or cutting out under a load.
• Check EGR valve and solenoid operation.
• Ensure PCV valve system is operating properly.
• Determine if condition is caused by a rich or lean system. Using scan tool, measure O2S/HO2S output voltage while driving vehicle when condition exists. Voltage less than .45 volt, indicates a lean system. Voltage greater than .45 volt, indicates a rich system.
• Check O2S/HO2S operation and for RTV sealant or silicone contamination. Also check for sensor cracking or glycol contamination. This will cause a false high voltage signal to ECM. ECM will respond by reducing (leaner) air/fuel ratio.
• Ensure transaxle/transmission shift points are correct.
• Check Torque Converter Clutch (TCC) operation.
• Ensure correct ECM application. Check with dealer for latest ECM application.
• Check for engine overheating.
• Check for restricted air flow or coolant flow through radiator.
• Check water pump drive belt adjustment.
• Check for correct thermostat and coolant solution.
• Check coolant temperature sensor.
• Check for incorrect or damaged basic engine parts such as camshaft, cylinder heads or pistons.
• Check for excessive carbon build-up on engine components.
• Check for excessive oil entering the engine.