Backfires

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

POSSIBLE CAUSE ACTION


Exhaust system leaks ^ Visual inspection


Incorrect Air-Fuel mixture ^ Check Air-Fuel ratio, O2 sensor, perform injector balance test, inspect regulator operation (check vacuum line and return hose), check fuel pressure


EGR malfunction ^ Check EGR system.