GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 DTS 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Detonation/Spark Knock

Inspection/Test

Action

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

Sensor/System
    • Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance .
    • Inspect for vacuum leaks and any unmetered air.
    • Monitor the knock sensor (KS) system for excessive spark retard activity. Refer to the knock sensor description within the Electronic Ignition (EI) System Description .

Fuel System
    •  Test the fuel system for correct operation, restriction, volume, and pressure. Refer to Fuel System Diagnosis .
    • Test for proper operation of the fuel injectors. Refer to Fuel Injector Diagnosis .
    • Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect the throttle body for coking. Refer to Throttle Body Inspection and Cleaning .
    • Inspect for lean or rich conditions. Refer to DTC P0171, P0172, P0174 or P0175 Conditions for Running the DTC. Refer to DTC P0171 or P0172 or DTC P0174 or P0175 .
    • Ensure that quality fuel is being used. Consult the Vehicle Owner's Manual.

Ignition System
    • Inspect for proper ignition system operation. Refer to Electronic Ignition (EI) System Diagnosis .
    • Inspect the spark plugs. Refer to Spark Plug Inspection .
    • Inspect the spark plugs for correct application. Refer to Ignition System Specifications .
    • Inspect for damaged ignition coils within the ignition coil module assemblies.
    • Inspect for damaged or misaligned spark plug boots.
    • Inspect for a missing or damaged ignition module ground spring.

Engine Mechanical
    • Inspect the engine mechanical for oil consumption, carbon build up within the combustion chamber, correct engine compression, and correct base engine timing. Refer to Symptoms - Engine Mechanical .
    • Inspect the combustion chamber for excessive carbon buildup.
    • Inspect for correct base engine timing. Refer to Symptoms - Engine Mechanical .
    • Inspect the following for incorrect basic engine parts:
      • Camshafts
      • Cylinder heads
      • Pistons

Additional Inspections
    • Inspect the engine cooling system. Refer to Engine Overheating .
    • Inspect the torque converter clutch (TCC) system for proper operation. Refer to Torque Converter Diagnosis .