{"model":"mk3","model_name":"MK3 Supra","vehicle":"Toyota Supra A70 (1986.5–1992, 7M-GE / 7M-GTE)","document":"Repair Manual","section":"FI","section_name":"EFI System","page":19,"pages_in_section":126,"title":"Symptom — Engine BACKFIRES-Lean Fuel Mixture","section_header":"EFI System — Troubleshooting","ocr_text":"EFI SYSTEM — Troubleshooting                                                                                                    FI-19\n\nSYMPTOM — ENGINE BACKFIRES-Lean Fuel Mixture\n\nCHECK DIAGNOSIS SYSTEM\n(Check for output of diagnostic code.\n(See page FI-23)\n\nNormal code\n\nCHECK FOR VACUUM LEAKS IN AIR\nINTAKE LINE\n\nOK\n\nCHECK IGNITION TIMING\n1. Connect terminals TE1 and E1 of the\n   check connector.\n2. Check ignition timing.\n   STD: 10° BTDC @ idle\n   (w/ connect terminals TE1 and E1)\n\nOK\n\nCHECK COLD START INJECTOR\n(See page FI-77)\n\nOK\n\nCHECK FUEL PRESSURE\n(See page FI-71)\n\nOK\n\nCHECK INJECTORS\n(See page FI-83)\n\nOK\n\nCHECK EFI ELECTRONIC CIRCUIT\nUSING VOLT/OHMMETER\n(See pages FI-30, 49)\n\nMalfunction\ncode(s)\n\nBAD\n\nNO\n\nBAD\n\nBAD\n\nBAD\n\nBAD\n\nDiagnostic code(s) (See page FI-26)\n\n1. Oil filler cap\n2. Oil dipstick\n3. Hose connections\n4. PCV hoses\n\nAdjust ignition timing (See page IG-20)\n\n1. Cold start injector\n2. Cold start injector time switch\n   (See page FI-112)\n\n1. Fuel pump (See page FI-70)\n2. Fuel filter\n3. Fuel pressure regulator (See page FI-81)\n\nInjectors — Clogged\n\n1. Wiring connection\n2. Power to ECU\n   (1) Fusible links\n   (2) Fuses\n   (3) EFI main relay\n3. Air flow meter\n4. Water temp. sensor\n5. Air temp. sensor\n6. Throttle position sensor\n7. Injection signal circuit\n   (1) Injection wiring\n   (2) Resistor (7M-GTE)\n   (3) ECU\n   (4) Fuel cut signal\n8. Oxygen 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transcript of a scanned Toyota factory manual page; verify critical values (torque specs, part numbers) against the image."}