GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Alero 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 Backfire

Backfire

Tests/Inspections

Actions

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

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

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

Ignition System
    • Test for the correct ignition voltage output with the J 36012-A spark plug jumper wires and J 26792 spark tester or equivalent.
    • Inspect the spark plugs for the following conditions:
       - Any wet or fuel fouled plugs
       - Any cracks
       - An incorrect gap
       - Any burnt electrodes or heavy deposits
    • If the spark plugs are fouled, the cause of the fouling must be determined before replacing the spark plugs.
    • Inspect the ignition control module (ICM) for a correct ground connection.
    • Inspect the ignition coils for cracks or carbon tracking.

Engine Mechanical
    • Inspect for the following conditions:
       - A low compression. Refer to Engine Compression Test in Engine Mechanical.
       - Any broken valve springs.
       - Any sticking or leaking valves.
       - Any worn camshafts lobes.
       - Any valve timing.
       - Any excessive oil in a combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
       - Refer to Symptoms - Engine Mechanical in Engine Mechanical.
    • Check for incorrect basic engine parts. Inspect the following:
       - The camshafts
       - The cylinder head
       - The pistons, etc.
       - Refer to Symptoms - Engine Mechanical in Engine Mechanical.

Additional
    • Inspect the intake manifold and the exhaust manifolds for casting flash. Refer to Symptoms - Engine Mechanical in Engine Mechanical .
    • Inspect the exhaust system for the following conditions:
       - Any damaged or collapsed pipes
       - Any heat distress or internal failure of the muffler
       - A plugged 3-way catalytic converter. Refer to Restricted Exhaust in Engine Exhaust .