Detonation/Spark Knock
Checks
| Action
|
DEFINITION : A mild to severe ping, usually worse during acceleration. The
engine makes sharp metallic knocks that change with the throttle opening.
|
Preliminary Checks
|
| • | Inspect the powertrain control module (PCM) grounds. Ensure that they
are clean, tight, and in the proper locations. Refer to
Engine Controls Schematics
. |
| • | Refer to supporting text of the Diagnostic System Check-Engine Controls.
If the scan tool readings are normal , and if no engine mechanical faults exist,
fill the fuel tank with a known high-quality fuel that meets the vehicle's minimum
octane requirements. Road test the vehicle, and re-evaluate the vehicle's
performance. |
|
Fuel System
|
| • | Inspect the items that can cause an engine to run lean, with a long-term
fuel trim near 24 percent. For a lean condition, refer to
DTC P0131 or P0151
. |
|
Ignition System
| Inspect the spark plugs for the proper heat range.
|
Engine Cooling System
| Inspect for the following obvious overheating conditions:
|
Engine Mechanical
| Inspect for the following engine mechanical conditions:
| • | Excessive oil in the combustion chamber caused by leaking valve seals--Refer
to
Oil Consumption Diagnosis
in Engine Mechanical-5.7L. |
| • | Excessive carbon buildup in the combustion chambers--Clean the combustion
chamber by using a quality engine cleaner. Follow the instructions on the can. |
| • | Inspect for incorrect basic engine parts. Inspect the following components: |
Refer to
Symptoms - Engine Mechanical
in Engine Mechanical-5.7L.
|
Additional Checks
|
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