GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Firefly (Canada) 🢒 Engine 🢒 Engine Controls - 1.3L 🢒 Backfire

Checks

Action

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

Preliminary Check
    • Refer to Symptoms .

Ignition System Checks
    • Check for adequate ignition coil voltage with a J 26792 spark tester or with an equivalent.
    • Check the spark plugs for any of the following conditions:
       - Wet plugs
       - A bent or loose terminal screw
       - A ceramic insulator that has cracks, has carbon tracking, or has deposits
       - A tip insulator that has cracks, has carbon tracking, has deposits, or is loose
       - A center electrode that is loose
       - An incorrect spark plug gap that is too large or too small.
       - Refer to Spark Plug Visual Diagnosis in Engine Electrical.
    • Check for crossfiring between spark plugs

Engine Mechanical Checks
    • Check for any of the following engine mechanical conditions:
       - An incorrect valve lash
       - Broken valve springs or weak valve springs
       - Low compression
       - Sticking valves or leaking valves
       - Incorrect valve timing
       - An incorrect camshaft or a worn camshaft
    • Check the intake and the exhaust system for casting flash or for other restrictions.

Additional Checks
    • Check for the correct fuel pressure. Refer to Fuel System Diagnosis .
    • Check the PCM grounds for being clean, tight, and in the correct locations. Refer to

Cell 21: Power and Ground
Object Number: 278544 Size: FS
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    • Check the Service Bulletins for any updates or for any information.