SYMPTOM — ENGINE BACKFIRES-Lean Fuel Mixture CHECK DIAGNOSIS SYSTEM Check for output of diagnostic code. (See page FI-22) Normal code CHECK FOR VACUUM LEAKS IN AIR INTAKE LINE OK CHECK IGNITION TIMING 1. Short both terminals of the check connector. 2. Check ignition timing. STD: 10° BTDC (w/short terminals of the check connector) OK CHECK COLD START INJECTOR (See page FI-49) OK CHECK FUEL PRESSURE (See page FI-45) OK CHECK INJECTORS (See page FI-53) OK CHECK EFI ELECTRONIC CIRCUIT USING VOLT/OHMMETER Malfunction code(s) BAD BAD BAD BAD BAD BAD Diagnostic code(s) (See page FI-22) 1. Oil filler cap 2. Oil level gauge 3. Hose connections 4. PCV hoses 5. EGR system — EGR valve stays open Ignition system (See page IG-2) 1. Cold start injector 2. Start injector time switch (See page FI-71) 1. Fuel pump (See page FI-44) 2. Fuel filter 3. Fuel pressure regulator (See page FI-52) Injectors — clogged 1. Wiring connection 2. Power to ECU (1) Fusible link (2) No.1 and No. 2 main relay 3. Air flow meter 4. Water temp. sensor 5. Air temp. sensor 6. Throttle position sensor 7. Injection signal circuit (1) Injection wirings (2) Resistor (3) ECU (4) Fuel cut signal 8. Oxygen sensor