Up to VIn #386333

DTC P0172 FUEL INJECTION SYSTEM FUNCTION





On Board Diagnosis 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 air fuel ratio (A/F) sensor 1. The
ECM calculates 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

NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

WITH CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON and select "SELF-LEARNING CONT" in "WORK SUPPORT" mode with CONSULT-III.
4. Clear the self-learning control coefficient by touching "CLEAR".
5. Start engine again and let it idle for at least 10 minutes.
6. Check 1st trip DTC.
The 1st trip DTC P0172 should be detected at this stage, if a malfunction exists. If so, go to "Diagnosis Procedure".

NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for 10 minutes. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following conditions should be satisfied at the same time.





7. If it is difficult to start engine at step 6, the fuel injection system has a malfunction, too.
8. Crank engine while depressing accelerator pedal.
If engine starts, go to "Diagnosis Procedure". If engine does not start, remove ignition plugs and check for fouling, etc.

WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.





3. Disconnect mass air flow sensor (1) harness connector.
4. Restart engine and let idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. Select Service $03 with GST. Make sure DTC P0102 is detected.
7. Select Service $04 with GST and erase the DTC P0102.
8. Start engine again and let it idle for at least 10 minutes.
9. Select Service $07 with GST. The 1st trip DTC P0172 should be detected at this stage, if a malfunction exists. If so, go to


NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for 10 minutes. Refer to the table below.
Hold the accelerator pedal as steady as possible.
The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following conditions should be satisfied at the same time.





10. If it is difficult to start engine at step 8, the fuel injection system has a malfunction.
11. Crank engine while depressing accelerator pedal.
If engine starts, go to "Diagnosis Procedure". If engine does not start, remove ignition plugs and check for fouling, etc.




Wiring Diagram















Diagnosis Procedure
1.CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).





OK or NG
OK >> GO TO 2.
NG >> Repair or replace.
2.CHECK FOR INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3.CHECK AIR FUEL RATIO (A/F) SENSOR 1 CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.





2. Disconnect air fuel ratio (A/F) sensor 1 harness connector (1).
- Air fuel ratio (A/F) sensor 1 (2)
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals. Refer to Wiring Diagram.






Continuity should exist.

5. Check harness continuity between ECM terminals 49, 53 or A/F sensor 1 terminals 1, 2 and ground. Refer to Wiring Diagram.

Continuity should not exist.


6. Also check harness for short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to Up to VIn #386333.
2. Install fuel pressure gauge and check fuel pressure. Refer to Up to VIn #386333.

At idling: Approximately 350 kPa (3.57 kg/cm2, 51 psi)


OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to Up to VIn #386333 Up to VIn #386333.)
- Fuel pressure regulator (Refer to Up to VIn #386333.)
>> Repair or replace.
6.CHECK MASS AIR FLOW SENSOR
With CONSULT-III
1. Install all removed parts.
2. Start engine and warm it up to normal operating temperature.
3. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-III.





With GST
1. Install all removed parts.
2. Start engine and warm it up to normal operating temperature.
3. Check mass air flow sensor signal in Service $01 with GST.






OK or NG
OK >> GO TO 7.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to P0101 P0101 P0101 P0101.
CHECK FUNCTION OF FUEL INJECTORS
With CONSULT-III
1. Let engine idle.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-III.
3. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT-III
1. Let engine idle.





2. Listen to each fuel injector operating sound.

Clicking noise should be heard.

OK or NG
OK >> GO TO 8.
NG >> Perform trouble diagnosis for Up to VIn #386333 Up to VIn #386333.
8.CHECK FUEL INJECTOR
1. Remove fuel injector assembly. Refer to Component Removal and Installation.
Keep fuel hose and all fuel injector connected to fuel tube.
2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Reconnect all harness connectors disconnected.
4. Disconnect all injector harness connectors.
5. Disconnect all ignition coil harness connectors.
6. Prepare pans or saucers under each fuel injector.
7. Crank engine for about 3 seconds.
Make sure fuel does not drip from fuel injector.
OK or NG
OK (Does not drip.)>>GO TO 9.
NG (Drips.)>>Replace the fuel injectors from which fuel is dripping. Always replace O-ring with new one.
9.CHECK INTERMITTENT INCIDENT
Refer to Up to VIn #386333 Up to VIn #386333.
>> INSPECTION END