Engine Controls - Trouble Shooting - No Codes: Symptoms: Backfire

NOTE: Fuel ignites in intake manifold, or in exhaust system, making a loud popping noise.

Check for:

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, see SYSTEM & COMPONENT TESTING article.
Check engine timing. See "Emission Control Information" label.
Check firing order.
Check for proper valve timing, timing gear and cam gear alignment. See 4.5L V8 article in ENGINE.
Remove rocker covers, check intake manifold bolt torque, check for bent push rods, broken or weak valve springs and check cam lift. Repair as necessary. See 4.5L V8 article in ENGINE.
Check AIR system for air to the exhaust manifold ports at all times.
Check for worn distributor gear, cam gear, timing chain and gear. See 4.5L V8 article in ENGINE.