For 1990-2009 cars

#### Detonation/Spark Knock

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

--

Go to Step 14

Go to Step 3

3 | Was visual/physical check performed? | -- | Go to Step 4 | Go to Visual/Physical Checks
4 | If scan tool readings are normal (refer to Engine Scan Tool Data List ) and there are no engine mechanical malfunctions, fill fuel tank with a known quality gasoline that has a minimum octane reading of 87 and re-evaluate vehicle performance. Is detonation present? | -- | Go to Step 5 | Go to Step 14
5 |

1. Check the Transaxle Range switch. Refer to DTC P0706 Trans Range Switch Performance .
2. If a problem is found, adjust the Transaxle Range switch as necessary. Refer to 4T60-E Transaxle On-Vehicle Service in section 7A.

Was a problem found?

--

Go to Step 14

Go to Step 6

6 |

1. Check TCC operation Refer to 4T60-E Automatic Transaxle Diagnosis .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 7

7 |

1. Check for obvious overheating problems:

• | Low engine coolant. Refer to Cooling and Radiator .

• | Restricted water flow through radiator. Refer to Cooling and Radiator .

• | Restricted air flow to radiator. Refer to Cooling and Radiator .

• | Inoperative electric cooling fan circuit(s). Refer to Electric Cooling Fan Diagnosis .

• | Correct coolant solution should be a 50/50 mix of approved antifreeze/coolant and water. Refer to Cooling and Radiator .

• | EGR operation. Refer to DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient .

2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 8

8 |

1. Check fuel pressure. Refer to Fuel System Pressure Test .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 9

9 |

1. Check items that can cause the engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids in DTC P0171 Fuel Trim System Lean .
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 10

10 |

1. Check spark plugs for proper heat range.
2. If incorrect spark plugs are installed, replace spark plugs as necessary. Refer to Ignition System .

Was a problem found?

--

Go to Step 14

Go to Step 11

11 |

1. Remove excessive carbon buildup with top engine cleaner. Refer to instructions included with the top engine cleaner.
2. Re-evaluate vehicle performance.

Is detonation still present?

--

Go to Step 12

Go to Step 14

12 |

1. Perform a cylinder compression check. Refer to Engine Compression Test in Engine General Information.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 13

13 |

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no malfunctions have been found, review/inspect the following:

• | Visual/physical inspection. Refer to Visual/Physical Checks .

• | Scan tool data. Refer to Engine Scan Tool Data List .

• | Freeze Frame data/Failure Records data.

• | All electrical connections within a suspected circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Review technical bulletins

14 | Operate the vehicle to duplicate conditions present when the original symptom was noticed. Is symptom still present? | -- | Go to Step 3 | System OK