Checks
| Action
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DEFINITION: A mild to severe ping that is usually worse under acceleration.
The engine makes sharp metallic knocks that change with throttle opening.
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Preliminary Checks
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• | Road test the vehicle in order to determine the severity of the condition. |
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Cooling System Checks
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• | Check for any obvious overheating problems. Refer to
Engine Overheating
in Engine Cooling. |
• | Check for a low engine coolant level. Refer to
Loss of Coolant
in Engine Cooling. |
• | Check for a loose water pump belt. |
• | Check for restricted air flow to the engine compartment. |
• | Check for restricted coolant flow through the radiator. |
• | Check for the correct coolant solution. The solution should be a 50/50
mix of anti-freeze and water. |
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Sensor Check
| Check for an engine coolant temperature (ECT) sensor that has a shifted value.
Refer to
Temperature Versus Resistance - Engine Coolant Temperature Sensor
.
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Fuel System Checks
|
• | Check to determine if a lean system causes the condition. Drive the vehicle
at the speed of the complaint. Monitoring the fuel trim will help identify the problem.
If the system is lean, the long term fuel trim will be more than 20 percent. |
• | Check for inferior quality fuel and the proper octane rating. Refer to
Alcohol/Contaminants-in-Fuel Diagnosis
. Fill
the fuel tank with a known high quality fuel that meets the vehicles minimum octane
requirements. Road test the vehicle and re-evaluate the vehicle performance. |
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Ignition System Checks
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• | Inspect the spark plugs for excessive deposits that can glow and pre-ignite
the air/fuel mixture. Refer to
Spark Plug Inspection
. |
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Engine Mechanical Checks
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• | Check for carbon buildup. Remove the carbon with a top engine cleaner
product. Follow the manufacturer instructions on the container. |
• | Check for incorrect basic engine parts such as the cam, the heads, the
pistons, etc. |
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Additional Checks
|
• | Check for a dirty air filter or a restriction in the air induction system. |
• | Check for any Service Bulletins or updates. |
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