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
Symptoms
Important
Preliminary Checks Before Starting. |
• | Refer to
Symptoms
Visual/Physical
Checks |
|
Fuel System
|
• | Check items that can cause an engine to run lean (Long Term FT
significantly in the positive range). Refer to Diagnostic Aids for
DTC P0171 Fuel Trim System Lean
. |
|
Ignition System
| Check the spark plugs for proper heat range and reach.
Refer to
Maintenance Items
|
Engine Cooling System
| Check for obvious overheating problems:
• | Restricted air flow to radiator, or restricted water flow through
radiator. |
|
Engine Mechanical
|
• | Combustion chambers for excessive carbon buildup. Clean using
top engine cleaner. Follow instructions on can. |
• | For incorrect basic engine parts. Inspect the following: |
|
Additional Checks
|
• | Check the transaxle range switch input with the vehicle in drive
and the gear selector in drive or overdrive. |
• | 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 (for VIN K, 91 for VIN 1) and re-evaluate
vehicle performance. |
|