GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Chevy K Silverado - 4WD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Fuel Knock/Combustion Noise

Checks

Action

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

Preliminary Checks
    • Refer to Symptoms - Engine Controls .
    • Ensure the vehicle has an actual problem.
    • Inspect for smoke associated with the combustion noise. Refer to Fuel System Checks below.

Cooling System Checks
    • Inspect for obvious overheating problems. Refer to Engine Overheating .
    • Inspect for a low engine coolant level.
    • Inspect for any restricted air flow through the radiator. Refer to Radiator Cleaning .
    • Inspect for a malfunctioning or incorrect thermostat.
    • Inspect for a correct coolant solution. The solution should be a 50/50 mix of anti-freeze and water.

Sensor Inspection
    • Inspect the engine coolant temperature (ECT) sensor by using the scan tool in order to compare the ECT with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or the sensor itself.
    • Inspect for an intermittent crankshaft position (CKP) sensor signal. Refer to Testing for Intermittent Conditions and Poor Connections .
    • Inspect the CKP sensor reluctor wheel. Remove the CKP sensor and attempt to move the reluctor wheel front to back or side to side with a probe. If there is any movement the reluctor wheel retaining bolts are loose.

Fuel System Checks

Important: Fuel additives are not recommended.

Inspect for the following:

    • Fuel contamination--Refer to Contaminants-in-Fuel Diagnosis .
    • A stuck fuel injector--Refer to Fuel Injector Balance Test with Tech 2 .

Engine Mechanical Checks
    • Inspect for incorrect basic engine parts such as cam, heads, pistons, etc.
    • If the engine control module (ECM) glow plug control module (GPCM) or a fuel injector has recently been replaced, it may be necessary to confirm the fuel injector flow rate values. Refer to Fuel Injector Flow Rate Programming .
    • Inspect for any excessive oil entering combustion chamber.

Additional Checks

Compare the scan tool data at idle with the scan tool data list. Refer to Scan Tool Data List .