Detonation/Spark Knock
Checks 
 | Action 
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DEFINITION: A mild to severe ping,
usually worse during acceleration. The engine makes        sharp metallic
knocks    that  change  with the throttle opening. 
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Preliminary Checks 
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|     •  | Search for service bulletins. |  
  
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Fuel System 
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|     •  | Inspect  for items that can cause an engine to run lean. Where
long term fuel trim significantly in the positive range. Refer to Diagnostic
Aids  for 
DTC P0171 
     . |  
  
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Ignition System 
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|     •  | Inspect  the knock sensor (KS) system for no retard timing. |  
  
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Engine Cooling System 
 | Inspect  for obvious overheating problems: 
|     •  | Restricted air flow to the radiator, or restricted water flow
through the radiator |  
  
|     •  | Inoperative electric cooling fan circuits |  
  
|     •  | Correct coolant solution should be a 50/50 mix of DEX-COOL®
or an equivalent antifreeze coolant and water. Refer to 
Engine Overheating 
 in Engine Cooling. |  
  
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Engine Mechanical 
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|     •  | Inspect the combustion chambers for excessive carbon buildup.
Clean the chambers using a good-quality engine cleaner. Follow the instructions
on the container. |  
  
|     •  | For incorrect basic engine parts. Inspect the following: |  
  
|        -  | Other engine parts, as appropriate |  
  
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Additional
Checks 
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|     •  | Inspect  the transaxle range switch input with the vehicle in
Drive and with the gear selector in Drive or Overdrive. |  
  
|     •  | Inspect  the torque converter clutch (TCC) operation. Applying
the TCC  too soon can cause the engine to spark knock. Refer to 
Torque Converter Diagnosis 
 in Automatic
Transaxle 3T40. |  
  
|     •  | If the scan tool readings are normal, and if there are no engine
mechanical malfunctions, fill the fuel tank with a known quality gasoline
that has a     minimum octane rating of 87 and re-evaluate the vehicle performance. |  
  
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