For 1990-2009 cars

#### Detonation/Spark Knock Symptom

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 Powertrain 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 Check
4 | If scan tool readings are normal (refer to Typical Scan Values) and there are no engine mechanical faults, 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 Transaxle Range switch circuit; use a scan tool and be sure the scan tool indicates that the vehicle is in drive with gear selector in drive or overdrive.
2. If a problem is found, diagnose and repair Transaxle Range switch as necessary Refer to 4T60-E Automatic Transaxle Diagnosis.

Was a problem found?

--

Go to Step 14

Go to Step 6

6 |

1. Check TCC operation. Refer to 4T60-E 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.

• | Restricted air flow to radiator, or restricted water flow through radiator.

• | Inoperative electric cooling fan circuit(s), use the Electric Cooling Fan Diagnosis.

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

• | EGR operation-refer to DTC P0401.

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 Diagnosis.
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 an engine to run lean (long term fuel trim significantly in the positive range). For a Lean condition, refer to Diagnostic Aids on diagnostic support page of DTC P0171.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 14

Go to Step 10

10 |

1. Spark plugs for proper heat range. Refer to General Information.
2. If incorrect spark plugs are installed, replace spark plugs as necessary.

Did any spark plugs require replacement?

--

Go to Step 14

Go to Step 11

11 |

1. Remove excessive carbon buildup with a top engine cleaner. Refer to instructions on top engine cleaner can.
2. Re-evaluate vehicle performance.

Is detonation still present?

--

Go to Step 12

Go to Step 14

12 |

1. Check for an engine mechanical problem. Perform a cylinder compression check (refer to Engine Mechanical section).
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.

• | Scan Tool data.

• | 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 Service Bulletins

14 | Operate the vehicle to duplicate conditions present when the original symptom was noted. Is symptom still present? | -- | Go to Step 3 | Repair complete