Section 90 (Engine Controls - Trouble Shooting - No Codes - EEC-V - Bi-Fuel): Symptoms: Backfires

WARNING: This page is about a different car, the 2002 Ford Pickup and 2002 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article.
Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - BI-FUEL article.
Check engine mechanical condition. Check compression, camshaft, valve train components, etc., and repair as necessary. See appropriate article in ENGINES.
Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & EXHAUST SYSTEMS under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article.