Backfires

Definition: Fuel ignites in intake manifold, or in exhaust System, making a loud popping noise.

^ Check for loose ground at the engine block.
^ Check for crossfire between spark plugs (distributor cap, spark plug wires, and proper routing of plug wires).
^ Check for intermittent condition in ignition system.
^ Check engine timing - see Emission Control Information label.
^ Check for proper valve timing - timing gear and cam gear alignment.
^ Remove rocker covers. Check intake manifold bolt torque. Check for bent push rods, broken or weak valve springs. Check cam lift. Repair as necessary.
^ Check AIR system for air to the exhaust manifold ports at all times.
^ Check for worn distributor gear, cam gear, timing chain and gears.