GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Tracker - 4WD 🢒 Engine 🢒 Engine Controls - 2.5L (LE8) 🢒 Backfire

Checks

Action

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

Preliminary Check
    • Refer to Symptoms - Engine Controls .

Ignition System Checks
    • Check for adequate ignition coil voltage with a J 26792 Spark Tester or equivalent. Refer to Electronic Ignition (EI) System Diagnosis .
    • Check for damaged or worn spark plugs. Refer to Spark Plug Inspection .
    • Check for the correct ignition timing. Refer to Ignition System Timing Adjustment .
    • Check for crossfiring between cylinders. Check for the correct routing of the ignition coil electrical connectors.

Engine Mechanical Checks
    • Check for any of the following engine mechanical problems:
       - Incorrect valve lash
       - Broken or weak valve springs
       - Low compression. Refer to Engine Compression Test in Engine Mechanical.
       - Sticking or leaking valves
       - Incorrect valve timing
       - Worn or incorrect camshaft
    • Refer to Symptoms - Engine Mechanical in Engine Mechanical.
    • Check the intake and exhaust system for casting flash or other restrictions.

Additional Checks
    • Check for the proper fuel pressure. Refer to Fuel System Diagnosis .
    • Verify the PCM grounds are clean, tight, and in the proper locations. Refer to Engine Controls Schematics .
    • Check the Service Bulletins for any updates or information.