Detonation/Spark Knock
Inspection/Test
| Action
|
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine
makes sharp metallic knocks that change with throttle opening.
|
Preliminary
|
| • | Refer to Important Preliminary Checks Before Starting. |
| • | Refer to Visual/Physical Checks. |
|
Fuel System
|
| • | Inspect items that can cause an engine to run lean (long term fuel trim
significantly in the positive range). Refer to Diagnostic Aids for
DTC P0171
. |
|
Ignition System
| Inspect the spark plugs for proper heat range and reach.
|
Engine Cooling System
| Inspect for obvious overheating conditions:
| • | Restricted air flow to radiator, or restricted water flow through radiator |
|
Engine Mechanical
|
| • | Excessive oil in combustion chamber--Leaking valve seals |
| • | Low cylinder compression |
| • | Combustion chambers for excessive carbon buildup--Clean using top
engine cleaner. Follow instructions on can. |
| • | For incorrect basic engine parts--Inspect the following: |
|
Additional
|
| • | Inspect the Transaxle Range Switch input with the vehicle in drive and
the gear selector in drive or overdrive. |
| • | Test torque converter clutch (TCC) operation. TCC applying too soon can
cause the engine to spark knock. Refer to
Torque Converter Diagnosis
in Automatic Transaxle-4T65-E. |
| • | If scan tool readings are normal and there are no engine mechanical faults,
fill the fuel tank with a known quality gasoline that has a minimum octane reading
of 87 and re-evaluate vehicle performance. |
|
