Detonation/Spark Knock. Chevrolet Corvette 1999

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 Detonation/Spark Knock

Detonation/Spark Knock

Checks

Action

DEFINITION: A mild to severe ping which usually occurs worse while under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

Preliminary Checks

•	Refer to Important Preliminary Checks Before Starting in Symptoms .

•	Search for bulletins.

•	Inspect the PCM grounds for being clean, tight, and in their proper locations. Refer to Engine Controls Schematics .

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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 tanks with a known high quality fuel that meets the vehicle's minimum octane requirements. Refer to Fuel System Specifications . Road test the vehicle and re-evaluate the vehicle's performance.

Fuel System

•	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .

•	Test for a restricted fuel filter. Refer to Fuel System Diagnosis .

•	Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Test the items that can cause an engine to run lean (long term fuel trim near 23%). For a lean condition, refer to DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 and DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1 .

Ignition System

Inspect the spark plugs for being the proper heat range. Refer to Spark Plug Usage in Engine Electrical.

Engine Cooling System

Test for obvious overheating problems:

•	Low engine coolant. Refer to Cooling System Draining and Filling 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.

•	Inoperative electric cooling fan circuits. Refer to Electric Cooling Fan Diagnosis .

Engine Mechanical

Inspect for the following engine mechanical problems:

•	Excessive oil in combustion chamber-Leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.

•	Low cylinder compression. Refer to Engine Compression Test in Engine Mechanical.

•	Combustion chambers for excessive carbon buildup. Clean the combustion chamber by using top engine cleaner. Follow the instructions on the can.

•	Inspect for incorrect basic engine parts. Inspect the following:

Camshaft

-	Cylinder heads

-	Pistons, etc.

•	Refer to Engine Mechanical.

Additional Checks

•	Test the Park/Neutral Position (PNP) switch operation. Refer to DTC P0705 Trans Range Switch Circuit or DTC P0706 Trans Range Switch Performance .

•	Test the Transmission Torque Converter Clutch (TCC) for proper operation. Applying the TCC too soon can cause the engine to spark knock. Refer to Functional Test in Automatic Transmission-4L60 E.