For 1990-2009 cars

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

• | Refer to Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Symptoms .

• | Road-test the vehicle in order to determine how severe the condition is.

Cooling System Checks |

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

• | Check for a low engine coolant level.

• | Check for a loose water pump belt.

• | Check for restricted airflow or for restricted coolant flow through the radiator.

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

• | Check for the correct coolant solution. The solution should be a 50/50 mix of coolant and of water. Refer to Coolant Concentration Testing in Engine Cooling.

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

• | Determine if 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 values of the Long Term Fuel Trim will approach 20 percent if a lean fueling condition is present. Refer to DTC P0171 Fuel Trim System Lean Diagnostic Aids.

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

• | Check the fuel injectors. Perform the Fuel Injector Coil Test and the Fuel Injector Balance Test. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and to Sequential Multiport Fuel Injector Balance Test .

• | Check for poor quality fuel and for 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's minimum octane requirements. Road-test the vehicle, and reevaluate vehicle performance.

Ignition System Checks | Check the spark plugs for the correct heat range and for the correct gap.
Engine Mechanical Checks |

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

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

• | Check for excessive oil that is entering the combustion chamber. Repair as necessary.

Additional Checks |

• | Check for the correct shifting and for the correct operation of the transmission. Refer to Road Test in Automatic Transmission.

• | Check for the correct operation of the air induction system.

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