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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Sunfire 🢒 Engine 🢒 Engine Controls - 2.2L (LN2) 🢒 Backfire

Backfire

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

Preliminary Checks
    • Refer to Symptoms - Engine Controls .
    • Search for service bulletins.

Fuel System
    • Inspect for low fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Ensure that each injector harness is connected to the correct injector/cylinder. Refer to Engine Controls Schematics .

Ignition System
    • Ensure proper ignition voltage output with the J 26792 Spark Tester or equivalent.
    • Inspect the spark plugs for the following conditions:
       - Wet or fuel fouled spark plugs
       - Cracks on the spark plugs
       - Wear
       - Improper spark plug gap
       - Burned electrodes or heavy deposits
    • If the spark plugs are fuel or oil-fouled, determine the cause of the fouling before replacing the spark plugs.
    • Inspect the ignition control module (ICM) for proper ground connection.
    • Inspect the ignition coils for cracks or carbon tracking.
    • Inspect the spark plug wires for proper resistance and condition.

Engine Mechanical
    • Inspect the engine mechanical for the following conditions:
       - Incorrect compression
       - Sticking or leaking valves
       - Worn camshaft lobes
       - Incorrect valve timing
       - Bent push rods
       - Worn rocker arms
       - Broken valve springs
       - Excessive oil in combustion chamber due to leaking valve seals
       - Low cylinder compression
    • Inspect for incorrect basic engine parts. Inspect the following components:
       - The camshaft
       - The cylinder heads
       - The pistons
       - Other engine parts, as appropriate
    • Refer to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical-2.2L.

Additional Checks
    • Inspect the intake and exhaust manifolds for casting flash. Refer to Symptoms - Engine Mechanical in Engine Mechanical-2.2L.
    • Inspect the exhaust system for a possible restriction. Inspect the following conditions:
       - The exhaust system for damaged or collapsed pipes.
       - The mufflers for heat distress, or for possible internal failure.
       - A possible plugged three-way catalytic converter (TWC). Refer to Restricted Exhaust in Engine Exhaust.