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.
CTS with a changed value. Compare to
resistance chart in COMPONENT TESTS
^ KNOCK SENSOR.
Refer to COMPONENT TESTING.




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.