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
|
| • | Refer to Important Preliminary Checks Before Starting in
Symptoms
. |
| • | If the scan tool readings are normal refer to supporting text
of the Powertrain On-Board Diagnostic (OBD) System Check and there are
no engine mechanical faults, fill the fuel tank with a
known high quality fuel that meets the vehicles minimum octane requirements.
Refer to Fuel System Specifications
.
Road test the vehicle and re-evaluate the vehicles performance. |
|
Fuel System
|
|
Ignition System
| Check the spark plugs for being the proper heat range.
Refer to
Spark Plug Visual Diagnosis
in Engine Electrical.
|
Engine Cooling System
| Check for obvious
overheating problems:
| • | Low engine coolant -- Refer to
Loss of Coolant
in Engine Cooling for the type and amount of
engine coolant to be used. |
| • | Restricted air flow to the radiator or restricted coolant flow
through the radiator. |
|
Engine Mechanical
| Check for the following engine mechanical problems:
| • | Excessive oil in combustion chamber -- Leaking valve seals.
Refer to
Oil Consumption Diagnosis
in Engine Mechanical 4.8L, 5.3L, 6.0L. |
| • | Combustion chambers for excessive carbon buildup -- Clean
the combustion chamber by using top engine cleaner. Follow the instructions
on the can. |
| • | Check for incorrect basic engine parts. Inspect the following: |
| • | Refer to Engine/Engine Mechanical. |
|
Additional Checks
|
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