For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: A mild to severe ping that is usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
Preliminary Checks |

• | Refer to Diagnostic System Check - Engine Controls .

• | Refer to Symptoms - Engine Controls .

• | Road test the vehicle in order to determine the severity of the condition.

Cooling System Checks |

• | Check for any obvious overheating problems. Refer to Engine Overheating in Engine Cooling.

• | Check for a low engine coolant level. Refer to Loss of Coolant in Engine Cooling.

• | Check for a loose water pump belt.

• | Check for restricted air flow to the engine compartment.

• | Check for restricted coolant flow through the radiator.

• | Check for a faulty or incorrect thermostat. Refer to Thermostat Diagnosis in Engine Cooling.

• | Check for the correct coolant solution. The solution should be a 50/50 mix of anti-freeze and water.

Sensor Check | Check for an engine coolant temperature (ECT) sensor that has a shifted value. Refer to Temperature Versus Resistance .
Fuel System Checks |

• | Determine whether lean fueling is causing the condition. Drive the vehicle at the speed of the complaint. Monitor the Fuel Trim value while listening for engine noise. The long term fuel trim values will be approaching 20 percent if a lean fueling condition is present. Refer to Diagnostic Aids in DTC P0171 and DTC P0174 .

• | Check for the correct fuel pressure. Refer to Fuel System Diagnosis .

• | Check the fuel injectors for correct operation and performance. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and to Fuel Injector Balance Test with Special Tool .

• | Check for inferior quality fuel and the correct octane rating. Refer to Fuel System Specifications . Drain and fill the fuel system with a known high quality fuel that meets the vehicle minimum octane requirements. Road test the vehicle and re-evaluate vehicle performance.

Ignition System Checks | Check the spark plugs for the proper heat range and gap. Refer to Ignition System Specifications
Engine Mechanical Checks |

• | Check for carbon buildup. Remove the carbon buildup with top engine cleaner. Follow the instructions on the container.

• | Check for incorrect basic engine parts such as the camshaft, heads, pistons, etc.

• | Check for an excessive quantity of oil entering the combustion chamber. Refer to Oil Consumption Diagnosis in Engine Mechanical.

Additional Checks |

• | Check for the proper shifting and operation of the transmission.

• | Check for a dirty air filter or restrictions in the air induction system.

• | Check the Service Bulletins for any updates or information.