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EC-222 < COMPONENT DIAGNOSIS > [VQ35HR] P0171, P0174 FUEL INJECTION SYSTEM FUNCTION P0171, P0174 FUEL INJECTION SYSTEM FUNCTION DTC Logic INFOID:0000000000956611 DTC DETECTION LOGIC With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the DTC CONFIRMATION PROCEDURE 1. PRECONDITIONING If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at >> GO TO 2. 2. PERFORM DTC CONFIRMATION PROCEDURE-I 1. Clear the mixture ratio self-learning value. Refer to EC-21, "MIXTURE RATIO SELF-LEARNING VALUE CLEAR : Special Repair Requirement" . 2. Start engine. Is it difficult to start engine? YES >> GO TO 3. NO >> GO TO 4. 3. RESTART ENGINE If it is difficult to start engine, the fuel injection system has a malfunction, too. YES >> Go to NO >> Check exhaust and intake air leak visually. 4. PERFORM DTC CONFIRMATION PROCEDURE-II 1. Keep engine idle for at least 10 minutes. 2. Check 1st trip DTC. Is 1st trip DTC detected? YES >> Go to NO >> GO TO 5. 5. PERFORM DTC CONFIRMATION PROCEDURE-III 1. Turn ignition switch OFF and wait at least 10 seconds. Sensor Input signal to ECM ECM function Actuator A/F sensor 1 Density of oxygen in exhaust gas Fuel injection control Fuel injector DTC No. Trouble diagnosis name DTC detecting condition Possible cause P0171 Fuel injection system too • Fuel injection system does not operate properly. large. (The mixture ratio is too lean.) • Intake air leaks P0174 Fuel injection system too |