For 1990-2009 cars

#### Detonation/Spark Knock

Tests/Inspections | Action
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DEFINITION: A mild to severe Ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
Preliminary |

• | Refer to Diagnostic System Check - Engine Controls .

• | Refer to Symptoms - Engine Controls .

• | Search for service bulletins.

Fuel System |

• | Test the fuel pressure. Refer to Fuel System Diagnosis .

• | Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• | Inspect the items that can cause an engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 .

Ignition System |

• | Inspect the spark plugs for the correct heat range and size. Refer to Ignition System Specifications .

• | Use a scan tool in order to verify that the ignition timing is not retarding.

Cooling System | Inspect for obvious overheating problems:

• | A low coolant level

• | An incorrect coolant mix.

• | A restricted air flow to the radiator, or a restricted water flow through radiator

• | Any inoperative cooling fans

• | An incorrect thermostat operation. Refer to Thermostat Diagnosis in Engine Cooling.

Engine Mechanical |

• | Any excessive oil in the combustion chamber and leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.

• | A high cylinder compression. Refer to Engine Compression Test in Engine Mechanical.

• | For any incorrect basic engine parts. Inspect the following:

- | The camshafts

- | The cylinder head

- | The pistons, etc.

Additional |

• | Test for the correct operation of the manifold absolute pressure (MAP) sensor. Verify that the MAP sensor is not out of range.

• | Inspect the Park/Neutral position switch input with the vehicle in drive and the gear selector in drive or overdrive.

• | Test for correct operation of the TCC. A TCC applying too soon can cause the engine to spark knock. Refer to Road Test in Automatic Transaxle.

• | If scan tool readings are normal and there are no engine mechanical malfunctions, fill the fuel tank with a known good gasoline that has a minimum octane reading of 87 and re-evaluate the vehicle's performance.