Infiniti M35/M45 Y50. Manual - part 461

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-317

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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-318

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DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

8. 

CHECK FUNCTION OF FUEL INJECTOR-I

 Without CONSULT-II

1.

Turn ignition switch OFF.

2.

Disconnect harness connectors F221 (1), F33 (2).

–

: vehicle front

–

Cylinder head (bank 2) (3)

3.

Turn ignition switch ON.

4.

Check voltage between harness connector F33 terminal 5 and
ground with CONSULT-II or tester.

5.

Turn ignition switch OFF.

6.

Disconnect ECM harness connector.

7.

Check harness continuity between the following terminals.

8.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 9.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-669, "FUEL INJECTOR"

 .

PBIB2785E

Voltage: Battery voltage

Cylinder

Harness connector F33 terminal

ECM terminal

1

6

23

2

4

42

3

2

22

4

3

41

5

1

21

6

7

40

Continuity should exist.

PBIB2323E

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

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9. 

CHECK FUNCTION OF FUEL INJECTOR-II

Provide battery voltage between the following terminals, and then
interrupt it. Listen to each fuel injector operating sound.

OK or NG

OK

>> GO TO 10.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-669, "FUEL INJECTOR"

 .

10. 

CHECK FUEL INJECTOR

1.

Turn ignition switch OFF.

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 fuel injector harness connectors.

5.

Remove fuel tube assembly. Refer to 

EM-47, "FUEL INJECTOR AND FUEL TUBE"

 .

Keep fuel hose and all fuel injectors connected to fuel tube.

6.

For DTC P0171, reconnect fuel injector harness connectors on bank 1.
For DTC P0174, reconnect fuel injector harness connectors on bank 2.

7.

Disconnect all ignition coil harness connectors.

8.

Prepare pans or saucers under each fuel injector.

9.

Crank engine for about 3 seconds.
For DTC P0171, make sure that fuel sprays out from fuel injec-
tors on bank 1.
For DTC P0174, make sure that fuel sprays out from fuel injec-
tors on bank 2.

OK or NG

OK

>> GO TO 11.

NG

>> Replace fuel injectors from which fuel does not spray

out. Always replace O-ring with new ones.

11. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-153, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

Cylinder

Harness connector F221 terminal

(+)

(–)

1

5

6

2

4

3

2

4

3

5

1

6

7

Operating sound should exist.

PBIB2497E

Fuel should be sprayed evenly for each fuel injector.

PBIB1726E

EC-320

[VQ35DE]

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION

PFP:16600

On Board Diagnosis Logic

NBS004XW

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

NBS004XX

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 1

Density 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) condition

When 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).