Detonation/Spark Knock/Pings

Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

PRELIMINARY CHECKS
^ Refer to Important Preliminary Checks. Testing and Inspection
^ Make sure the customer has an actual problem.

IMPORTANT
^ If scan tool readings are normal and there are no engine mechanical faults, fill fuel tank with a known good grade of gasoline that has a minimum octane rating of 87 to 89 and revaluate vehicle performance.
^ Transmission Range (TR) pressure switch assembly operation.

COOLING SYSTEM
CHECK: For obvious over heating problems.
CHECK: Low engine coolant.
CHECK: Loose water pump belt.
CHECK: Restricted air flow to radiator, or restricted coolant flow.
CHECK: Faulty or incorrect thermostat.
CHECK: Correct coolant solution.

FUEL SYSTEM
CHECK: To determine if the condition is caused by a lean system, the vehicle should be driven at the speed of the complaint. Monitoring fuel trim will help identify the problem.
- Lean - Long term fuel trim greater than 150. Refer to Diagnostic Charts/Trouble Code Charts/Code 44 Oxygen Sensor (Lean Exhaust Indication) - Diagnostic Aids. Powertrain Controls - ECM/PCM
CHECK: Fuel pressure. Refer to Diagnostic Charts/Chart A-6 Fuel System Diagnosis Related Tests, Information and Procedures
CHECK: For poor fuel quality and proper octane rating.

IGNITION SYSTEM
CHECK: Spark plugs for proper heat range and gap.
CHECK: Knock Sensor (KS) system operation.
CHECK: Ignition timing.

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.

ADDITIONAL CHECKS
CHECK: Proper operation of EGR valve.
CHECK: Proper operation of air intake system.
CHECK: For proper transmission shift points.
CHECK: [1][2]Torque Converter Clutch (TCC) operation.
CHECK: Service Bulletins for PROM updates.
CHECK: Combustion chamber pressure by performing a compression test.