Detonation/Spark Knock/Pings

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 overheating 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.
^ MAP for proper operation.
^ PROM/MEM-CAL, refer to parameter
P.1.7 or ED17 or ED99.



FUEL NOTE: To determine if the condition is caused by
a lean system, the vehicle should be driven at the
speed of the complaint. If closed loop is achieved,
the fuel system has to checked for rich, lean or
improper fuel control. The DFI system has ECM
parameter ED19 "Integrator" which monitors the
oxygen sensor rich lean status and drives the fuel
system richer if the 02 sensor is lean or
leaner if the sensor is rich.
To help identify the problem
Refer to DFI SYSTEM CHECK. Or codes E44, EO44
for lean conditions and E45, EO45 for rich
NOTES ON INTERMITTENTS
CHECK: ^ FUEL PRESSURE.
Refer to DIAGNOSTIC CHARTS/A-CHARTS
^ FUEL QUALITY.
Poor or contaminated fuel, proper octane rating.



IGNITION CHECK: ^ SPARK PLUGS for proper heat range.
^ EST 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.
^ Viscous Converter Clutch (VCC) operation.