Detonation/Spark Knock/Pings
DETONATION/SPARK KNOCKDefinition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
PRELIMINARY CHECKS
^ Perform the careful/physical visual checks as described at start of "Symptoms".
^ Make sure the customer has an actual problem.
^ Remove air filter and check air filter for dirt, or for being plugged, replace as necessary.
^ CHECK: PCV system for proper operation by placing finger over inlet hole in valve end several times with the engine idling. Valve should snap back. If not, check [1][2]PCV hose for blockage or deterioration and replace if necessary. If PCV still fails this test, replace it with the correct part number PCV valve.
ADDITIONAL CHECKS
^ CHECK: EGR operation. Refer to "Exhaust Gas Recirculation (EGR) System,"
^ CHECK: For proper transmission shift points.
^ CHECK: Torque Converter Clutch (TCC) operation. Use CHART C-8.
^ CHECK: For correct PROM or ECM (see Service Bulletins).
COOLING SYSTEM
^ CHECK: For obvious over heating problems.
^ CHECK: Low engine coolant.
^ CHECK: Restricted air flow to radiator, or restricted water flow thru radiator.
^ CHECK: Faulty or incorrect thermostat.
^ CHECK: Correct coolant solution - should be a 50/50 mix of anti-freeze coolant (or equivalent) and water.
SENSOR
^ CHECK: Engine Coolant Temperature (ECT) sensor, which has shifted in value.
Compare ECT resistance to the "Diagnostic Aids" chart in DTC 15 chart.
FUEL SYSTEM
NOTICE: To determine if the condition is caused by a rich or lean system, the vehicle should be driven at the speed of the complaint. Monitoring LT fuel trim will help identify the problem. Lean - LT fuel trim greater than 150. Refer to "Diagnostic Aids" in DTC 44.
Rich - LT fuel trim less than 115. Refer to "Diagnostic Aids" in DTC 45.
^ CHECK: Fuel pressure
^ CHECK: For poor fuel quality, proper octane rating.
NOTICE: If scan tool readings are normal ("On-Board Diagnostic System Check") and there are no engine mechanical faults, fill fuel tank with a premium gasoline that has a minimum octane rating of 92 and re-evaluate vehicle performance.
IGNITION SYSTEM
^ CHECK: Ignition timing. See "Vehicle Emission Control Information" label.
^ CHECK: Spark plugs for proper heat range.
^ CHECK: Ignition wires for shorts or faulty insulation.
^ CHECK: For misfiring, crossfiring or cutting out under load. Refer to "Ignition System Check" chart in "Distributor Ignition (DI),"
ENGINE MECHANICAL
^ CHECK: For carbon buildup. Remove carbon with top engine cleaner. Follow instructions on can.
^ CHECK: For incorrect basic engine parts such as cam, heads, pistons, etc.
^ CHECK: For excessive oil entering combustion chamber.