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 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. Check resistance at
different temperatures. DTC 14
^ PROM/MEM-CAL. Refer to COMPUTERIZED
ENGINE CONTROLS/PROM I.D. for correct
prom number.


FUEL NOTE: To determine if the condition is caused by
a lean system, the vehicle should be driven at the
speed of the complaint. Monitoring block learn will
help identify the problem (Lean - Block learn greater
than 150). DTC 44
CHECK: ^ FUEL PRESSURE.
[1][2]Chart A-7 Fuel System Diagnosis
Poor or contaminated fuel, proper octane rating.


IGNITION CHECK: ^ SPARK PLUGS for proper heat range.
Ignition wires for shorts or faulty insulation.
For DIS misfiring, crossfire or cutting out, see
COMPONENT TESTING (C-CHARTS).
^ ESC system operation.
^ TIMING.


EMISSIONS CHECK: ^ EGR operation. DTC 32
^ 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.