Detonation - Pings, Spark Knock

Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

1. Was the "On-Board Diagnostic (OBD) System Check" performed?

[YES] Go to Step 2.
[NO] Go to OBD System Check. Initial Inspection

2. a. Perform a bulletin search.
b. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.
c. Was a bulletin found that addresses the symptom?

[YES] Verify repair.
[NO] Go to Step 3.

3. Was a visual/physical check performed?

[YES] Go to Step 4.
[NO] Go to Visual/Physical Check. Visual/Physical Check

4. a. If scan tool reading are normal and there are no engine mechanical faults, fill the fuel tank with a known quality gasoline that has a minimum octane rating of 87.
b. Re-evaluate the vehicle performance.
c. Is detonation present?

[YES] Go to Step 5.
[NO] Verify repair.

5. a. Check the transmission range switch circuit. Use a scan tool and be sure the scan tool indicates that the vehicle is in drive with the gear selector in drive or overdrive.
b. If a problem is found, diagnose and repair the transmission range switch as necessary.
c. Was a problem found?

[YES] Verify repair.
[NO] Go to Step 6.

6. a. Check Torque Converter Clutch (TCC) operation.
b. If a problem is found, repair as necessary.
c. Was a problem found?

[YES] Verify repair.
[NO] Go to Step 7.

7. a. Check for obvious overheating problems:
- Low engine coolant.
- Restricted air flow to radiator, or restricted water flow through radiator.
- Correct coolant solution should be a 50/50 mix of approved antifreeze/coolant and water.
- Exhaust Gas Recirculation (EGR) operation. Refer to DTC PO401.
b. If a problem is found, repair as necessary.
c. Was a problem found?

[YES] Verify repair.
[NO] Go to Step 8.

8. a. Check fuel pressure. Refer to Fuel System Pressure Test.
b. c. Was a problem found?

[YES] Verify repair.
[NO] Go to Step 9.

9. a. 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 in DTC PO171.
b. If a problem is found, repair as necessary.
c. Was a problem found?

[YES] Go to Step 10.
[NO] Verify repair.

10. a. Check spark plugs for proper heat range.
b. If incorrect spark plugs are installed, replace spark plugs as necessary.
c. Did any spark plugs require replacement?

[YES] Verify repair.
[NO] Go to Step 11.

11. a. Remove excessive carbon buildup with a top engine cleaner. Refer to instructions on the top engine cleaner can.
b. Re-evaluate vehicle performance.
c. Is detonation still present?

[YES] Go to Step 12.
[NO] Verify repair.

12. a. Check for an engine mechanical problem.
b. Perform a cylinder compression check.
c. If a problem is found, repair as necessary.
d. Was a problem found?

[YES] Verify repair.
[NO] Go to Step 13.

13. a. Review all diagnostic procedures within this table.
b. 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 buffer.
- All electrical connections within a suspected circuit and/or system.
c. If a problem is found, repair as necessary.
d. Was a problem found?

[YES] Verify repair.
[NO] Contact Technical Assistance.