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P0172 FUEL INJECTION SYSTEM FUNCTION EC-301 < DTC/CIRCUIT DIAGNOSIS > [MR FOR NISMO RS MODELS] C D E F G H I J K L M A EC N P O P0172 FUEL INJECTION SYSTEM FUNCTION DTC Logic INFOID:0000000012197848 DTC DETECTION LOGIC With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the A/F sensors 1. The ECM calcu- lates the necessary compensation to correct the offset between the actual and the theoretical ratios. In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic). DTC CONFIRMATION PROCEDURE 1. PRECONDITIONING If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test. 1. Turn ignition switch OFF and wait at least 10 seconds. 2. Turn ignition switch ON. 3. Turn ignition switch OFF and wait at least 10 seconds. >> GO TO 2. 2. PERFORM DTC CONFIRMATION PROCEDURE-I 1. Clear the mixture ratio self-learning value. Refer to 2. 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. Crank engine while depressing accelerator pedal. NOTE: When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the engine. Do not depress accelerator pedal too much. YES >> Proceed to . NO >> Check exhaust and intake air leak visually. 4. PERFORM DTC CONFIRMATION PROCEDURE-II 1. Start engine and let it idle for at least 5 minutes. 2. Check 1st trip DTC. YES >> Proceed to . NO >> GO TO 5. 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 (Trouble diagnosis con- tent) DTC detecting condition Possible cause P0172 FUEL SYS-RICH-B1 • Fuel injection system does not operate properly. large. (The mixture ratio is too rich.) • A/F sensor 1 |