Backfires and Afterfires

Fuel ignites in the intake manifold or in exhaust system making a loud popping noise.

POSSIBLE CAUSE ACTION


EGR open all the time, (Except Montero) Check EGR system in "Testing
leaking gasket Procedures" in Emissions



Air management valves, Check Air Injection system in
Deceleration valve, "Testing Procedures" in Emissions
Check valves malfunctioning