Detonation/Spark Knock

SYMPTOM DESCRIPTION:
A mild or severe ping, usually worse under acceleration. The engine makes a sharp metallic knock as engine rpm varies.



SYSTEM OR COMPONENT TO CHECK ACTION



COOLING CHECK: - For obvious over heating problems.
- Low engine coolant level and leaks.
- Water pump operation, loose belts.
- Restricted air flow to radiator or
restricted coolant flow.
- Faulty or incorrect thermostat.
- Correct coolant solution - should be a 50/50
mix of anti-freeze (coolant) and water.
- Fan operation (electric or belt driven).



COMPUTER INPUTS/OUTPUTS CHECK: - COOLANT TEMPERATURE SENSOR.

- KNOCK SENSOR.





FUEL NOTE: To determine if the condition is caused by
a lean system, the vehicle should be driven at the
speed of the complaint. Refer to DIAGNOSTIC CHARTS.
CHECK: - FUEL PRESSURE
Refer to TESTING PROCEDURES under FUEL SYSTEMS
- FUEL QUALITY.
Poor or contaminated fuel, proper octane rating.



IGNITION CHECK: - SPARK PLUGS for proper heat range.
- SPARK CONTROL system operation.
- TIMING




EMISSIONS CHECK: - EGR operation.
- THERMOSTATIC AIR CLEANER operation.




ENGINE/TRANSMISSION CHECK: - Carbon buildup. Remove carbon with
top engine cleaner. Follow instructions on can.
- For incorrect basic engine parts such as cam,
heads, pistons, etc.
- For excessive oil entering combustion chamber.
- Proper transmission shift points.
- Torque Converter Clutch (TCC) operation.