Mass air flow INFINITI M35 2007 Factory Workshop Manual

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-309
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Revision: 2007 April2007 M35/M45
DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTIONPFP:16600
On Board Diagnosis LogicNBS004XS
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 lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
DTC Confirmation ProcedureNBS004XT
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-II
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 CON-
SULT-II.
4. Clear the self-learning control coefficient by touching “CLEAR”.
5. Select “DATA MONITOR” mode with CONSULT-II.
6. Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0171 or P0174 should be detected at this
stage, if a malfunction exists. If so, go to EC-315, "
Diagnostic
Procedure" .
NOTE:
If 1st trip DTC is not detected during above procedure, perform-
ing 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 con-
ditions should be satisfied at the same time.
Sensor Input signal to ECM ECM function Actuator
A/F sensor 1Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injection control Fuel injector
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0171
0171
(Bank 1)
Fuel injection system too
lean

Fuel injection system does not operate properly.

The amount of mixture ratio compensation is too
large. (The mixture ratio is too lean.)

Intake air leaks

A/F sensor 1

Fuel injector

Exhaust gas leaks

Incorrect fuel pressure

Lack of fuel

Mass air flow sensor

Incorrect PCV hose connection P0174
0174
(Bank 2)
SEF968Y
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).

EC-310
[VQ35DE]
DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
Revision: 2007 April2007 M35/M45
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 EC-315, "
Diagnostic Procedure" .
If engine does not start, check exhaust and intake air leak visually.
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 it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness con-
nector.
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 P0171 or P0174
should be detected at this stage, if a malfunction exists. If so, go
to EC-315, "
Diagnostic 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 min-
utes. 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 con-
ditions 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 EC-315, "
Diagnostic Procedure" .
If engine does not start, check exhaust and intake air leak visually.
PBIB2783E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-315
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Revision: 2007 April2007 M35/M45
Diagnostic ProcedureNBS004XV
1. CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1.
OK or NG
OK >> GO TO 2.
NG >> Repair or replace.
2. CHECK FOR INTAKE AIR LEAK
1. Listen for an intake air leak after the mass air flow sensor.
2. Check PCV hose connection.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
PBIB1922E

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-317
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Revision: 2007 April2007 M35/M45
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-88, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-89, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to EC-675, "FUEL PUMP" .)

Fuel pressure regulator (Refer to EC-89, "FUEL PRESSURE CHECK" .)

Fuel lines (Refer to FL-3, "FUEL SYSTEM" .)

Fuel filter for clogging
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
OK or NG
OK (With CONSULT-II)>>GO TO 7.
OK (Without CONSULT-II)>>GO TO 8.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to EC-193, "
DTC P0101 MAF SENSOR" .
7. CHECK FUNCTION OF FUEL INJECTOR
With CONSULT-II
1. Start engine.
2. Perform “POWER BALANCE” in “ACTIVE TEST” mode with
CONSULT-II.
3. Make sure that each circuit produces a momentary engine
speed drop.
OK or NG
OK >> GO TO 10.
NG >> Perform trouble diagnosis for FUEL INJECTOR, refer to
EC-669, "
FUEL INJECTOR" . At idling: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
PBIB0133E

EC-320
[VQ35DE]
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
Revision: 2007 April2007 M35/M45
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTIONPFP:16600
On Board Diagnosis LogicNBS004XW
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 ProcedureNBS004XX
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-II
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 CON-
SULT-II.
4. Clear the self-learning control coefficient by touching “CLEAR”.
5. Select “DATA MONITOR” mode with CONSULT-II.
6. Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0172, P0175 should be detected at this stage,
if a malfunction exists. If so, go to EC-326, "
Diagnostic Proce-
dure" .
NOTE:
If 1st trip DTC is not detected during above procedure, perform-
ing 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 con-
ditions 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.
Sensor Input signal to ECM ECM function Actuator
A/F sensor 1Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injection control Fuel injector
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0172
0172
(Bank 1)
Fuel injection system too
rich

Fuel injection system does not operate properly.

The amount of mixture ratio compensation is too
large. (The mixture ratio is too rich.)

A/F sensor 1

Fuel injector

Exhaust gas leaks

Incorrect fuel pressure

Mass air flow sensor P0175
0175
(Bank 2)
SEF968Y
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-321
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Revision: 2007 April2007 M35/M45
If engine starts, go to EC-326, "Diagnostic Procedure" . If engine does not start, remove spark 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. Then
restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness con-
nector.
5. Select Service $03 with GST. Make sure DTC P0102 is
detected.
6. Select Service $04 with GST and erase the DTC P0102.
7. Start engine again and let it idle for at least 10 minutes.
8. Select Service $07 with GST. The 1st trip DTC P0172 or P0175
should be detected at this stage, if a malfunction exists. If so, go
to EC-326, "
Diagnostic 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 min-
utes. 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 con-
ditions should be satisfied at the same time.
9. If it is difficult to start engine at step 7, the fuel injection system has a malfunction.
10. Crank engine while depressing accelerator pedal.
If engine starts, go to EC-326, "
Diagnostic Procedure" . If engine does not start, remove spark plugs and
check for fouling, etc.
PBIB2783E
Engine speed Engine speed in the freeze frame data ± 400 rpm
Vehicle speed Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
Engine coolant temperature
(T) conditionWhen the freeze frame data shows lower than 70 °C (158 °F),
T should be lower than 70 °C (158 °F).
When the freeze frame data shows higher than or equal to 70 °C (158 °F),
T should be higher than or equal to 70 °C (158 °F).

EC-326
[VQ35DE]
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
Revision: 2007 April2007 M35/M45
Diagnostic ProcedureNBS004XZ
1. CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1.
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.
PBIB1922E

EC-328
[VQ35DE]
DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
Revision: 2007 April2007 M35/M45
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-88, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-89, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to EC-675, "FUEL PUMP" .)

Fuel pressure regulator (Refer to EC-89, "FUEL PRESSURE CHECK" .)
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in “Service $01” with GST.
OK or NG
OK (With CONSULT-II)>>GO TO 7.
OK (Without CONSULT-II)>>GO TO 8.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to EC-193, "
DTC P0101 MAF SENSOR" .
7. CHECK FUNCTION OF FUEL INJECTOR
With CONSULT-II
1. Start engine.
2. Perform “POWER BALANCE” in “ACTIVE TEST” mode with
CONSULT-II.
3. Make sure that each circuit produces a momentary engine
speed drop.
OK or NG
OK >> GO TO 10.
NG >> Perform trouble diagnosis for FUEL INJECTOR, refer to
EC-669, "
FUEL INJECTOR" . At idling: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
PBIB0133E

EC-358
[VQ35DE]
DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MIS-
FIRE
Revision: 2007 April2007 M35/M45
16. REPLACE AIR FUEL RATIO (A/F) SENSOR 1
Replace malfunctioning air fuel ratio (A/F) sensor 1.
CAUTION:

Discard any A/F sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.

Before installing new A/F sensor, clean exhaust system threads using Oxygen Sensor Thread
Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
>>INSPECTION END
17. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Start engine and warm it up to normal operating temperature.
3. Check mass air flow sensor signal in “DATA MONITOR” mode with CONSULT-II.
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 18.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
ground. Refer to EC-193, "
DTC P0101 MAF SENSOR" .
18. CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in EC-99, "
Symptom Matrix Chart" .
OK or NG
OK >> GO TO 19.
NG >> Repair or replace.
19. ERASE THE 1ST TRIP DTC
Some tests may cause a 1st trip DTC to be set.
Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to EC-68, "
HOW TO ERASE
EMISSION-RELATED DIAGNOSTIC INFORMATION" .
>> GO TO 20.
20. CHECK INTERMITTENT INCIDENT
Refer to EC-153, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END 2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm
2.0 - 6.0 g·m/sec: at idling
7.0 - 20.0 g·m/sec: at 2,500 rpm

EC-382
[VQ35DE]
DTC P0420, P0430 THREE WAY CATALYST FUNCTION
Revision: 2007 April2007 M35/M45
Diagnostic ProcedureNBS004ZF
1. CHECK EXHAUST SYSTEM
Visually check exhaust tubes and muffler for dent.
OK or NG
OK >> GO TO 2.
NG >> Repair or replace.
2. CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before the three way catalyst 1.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3. CHECK INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace.
4. CHECK IGNITION TIMING
Check the following items. Refer to EC-78, "
Basic Inspection" .
OK or NG
OK >> GO TO 5.
NG >> Follow the EC-78, "
Basic Inspection" .
PBIB1922E
Items Specifications
Target idle speed 650 ± 50 rpm (in P or N position)
Ignition timing 15 ± 5° BTDC (in P or N position)