Spark Knock/Detonation

Check cooling system.
Check fuel pressure.
Check spark plugs.
Check ignition and valve timing.
Check for clogged fuel filter.
Check for vacuum leaks.
Check for excessive combustion chamber deposits.
Check for faulty throttle position sensor (if equipped).
Check for faulty coolant (water) temperature sensor.
Check for faulty MAP (pressure) sensor (if equipped).
Check for malfunctioning electronic fuel injection system.
Check for malfunctioning EGR valve (if equipped).
Ensure sufficient secondary spark is available.