Detonation/Spark Knock
Checks
| Action
|
DEFINITION: A mild
to severe ping, usually worse under acceleration. The engine makes sharp metallic
knocks that change with throttle opening.
|
Preliminary Checks
|
| • | Verify that the powertrain control module (PCM) grounds are clean,
tight, and in the correct locations. |
| • | If the scan tool readings are normal refer to
Diagnostic System Check - Engine Controls
and there are no engine mechanical faults,
fill the fuel tank with a premium gasoline that has a minimum octane
reading of 92 and re-evaluate the vehicle's performance. |
|
Fuel System
|
| • | Inspect for a restricted fuel filter. |
| • | Inspect the items that can cause an engine to run rich. |
| • | Inspect items that can cause an engine to run lean. |
|
Ignition System
| Inspect the spark plugs for the correct heat range.
|
Engine Cooling System
| Inspect for obvious overheating problems:
| • | A low engine coolant level |
| • | A restricted airflow to the radiator, or restricted water flow
through the radiator |
Refer to
Engine Overheating
in
Engine Cooling.
|
Engine Mechanical
| Inspect for the following conditions:
| • | Any excessive oil in the combustion chambers may indicate leaking
valve seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
| • | Any excessive carbon buildup in the combustion chambers. Clean
the chambers using Top Engine cleaner. Follow the instructions on the container. |
| • | Any incorrect basic engine parts. Inspect the following: |
Refer to
Symptoms - Engine Mechanical
in
Engine Mechanical-3.5L.
|
Additional Checks
|
| • | Inspect for the correct transaxle range switch operation. |
|
