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 PCM grounds are clean, tight, and in the correct
locations. |
| • | If the scan tool readings are normal, refer to supporting text
of the
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
|
| • | Check for a restricted fuel filter. |
| • | Check the items that can cause an engine to run rich. |
| • | Check items that can cause an engine to run lean. |
|
Ignition System
| Check the spark plugs for the correct heat range.
|
Engine Cooling System
| Check for
obvious overheating problems:
| • | A low engine coolant level |
| • | A restricted air flow to the radiator, or restricted water flow
through the radiator |
| • | Check for any inoperative cooling fans. Refer to Electric Cooling
Fan Diagnosis. |
|
Engine Mechanical
| Check 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 parts: |
Refer to
Symptoms - Engine Mechanical
in Engine Mechanical.
|
Additional Checks
|
| • | Check for the correct transaxle range switch operation. |
|
