GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Geo 🢒 1997 🢒 Prizm 🢒 Engine 🢒 Engine Controls - 1.6L 🢒 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 .

Ignition System Checks
    • Check for the proper ignition coil output voltage with a spark tester (J 26792 or equivalent).
    • Check the spark plugs for any of the following conditions:
       - Wet (fuel fouled) plugs.
       - A terminal screw that is bent or loose (rotate and pull).
       - A ceramic insulator that has cracks, carbon tracking or deposits (red or black dust)
       - A tip insulator that has cracks, carbon tracking, deposits (oil, carbon, glazing, fuel additive), or is loose (rattles).
       - A center electrode that is loose (wiggles side to side)
       - An incorrect spark plug gap that is too large or too small.
       - Platinum pads that are missing.

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