GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Caprice WM 🢒 Engine 🢒 Engine Controls and Fuel - 2.8L, 3.0L, 3.2L, or 3.6L 🢒 Backfire

Backfire Petrol

Checks

Action

DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.

Preliminary Checks

Refer to Important Preliminary Checks in Symptoms - Engine Controls .

Ignition System Checks
    • Remove and inspect the spark plugs for the following conditions:
       - Wet plugs
       - Cracks
       - Wear
       - Incorrect gap
       - Burned electrodes
       - Heavy deposits
    • Test for correct ignition system operation.
    • Test for crossfire between spark plugs. Test for spark plug wire failure.

Engine Mechanical Checks
    • Inspect the engine for the following:
       - Intake manifold leaks
       - Incorrect valve timing
       - Correct engine cylinder compression
       - Sticking or leaking intake or exhaust valves
       - Exhaust system leakage
    • Inspect the intake and exhaust system for casting flash.

Fuel System Checks

Perform fuel system diagnosis. Refer to Fuel System Diagnosis .

Additional Checks
    • Review service bulletins for LPG ECM PCM programming updates.
    • Verify that the correct LPG software and calibration has been programmed into the LPG ECM.
    • Test for correct operation of the AFO Enable circuit.

Backfire LPG

Checks

Action

DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.

Preliminary Checks

Refer to Important Preliminary Checks in Symptoms - Engine Controls.

Ignition System Checks
    • Remove and inspect the spark plugs for the following conditions:
       - Wet plugs
       - Cracks
       - Wear
       - Incorrect gap
       - Burned electrodes
       - Heavy deposits
    • Test for correct ignition system operation.
    • Test for crossfire between spark plugs. Test for spark plug wire failure.

Engine Mechanical Checks
    • Inspect the engine for the following:
       - Intake manifold leaks
       - Incorrect valve timing
       - Correct engine cylinder compression
       - Sticking or leaking intake or exhaust valves
       - Exhaust system leakage
    • Inspect the intake and exhaust system for casting flash.

Fuel System Checks

Perform fuel system diagnosis. Refer to Fuel System Diagnosis.

Additional Checks
    • Review service bulletins for LPG ECM PCM programming updates.
    • Verify that the correct LPG software and calibration has been programmed into the LPG ECM.
    • Test for correct operation of the AFO Enable circuit.