Infiniti M35/M45 Y50. Manual - part 639

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-1029

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3. 

CHECK AIR FUEL RATIO (A/F) SENSOR 1 INPUT SIGNAL CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect corresponding air fuel ratio (A/F) sensor 1 harness connector.

3.

Disconnect ECM harness connector.

4.

Check harness continuity between the following terminals.
Refer to Wiring Diagram.

5.

Check harness continuity between the following terminals and ground.
Refer to Wiring Diagram.

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.

: Vehicle front

1.

A/F sensor 1 (bank 2) 
harness connector

2.

A/F sensor 1 (bank 1) 
harness connector

A/F sensor 1 terminal

ECM terminal

Bank 1

1

16

2

75

5

35

6

56

Bank 2

1

76

2

77

5

57

6

58

Continuity should exist.

Bank 1

Bank 2

A/F sensor 1 terminal

ECM terminal

A/F sensor 1 terminal

ECM terminal

1

16

1

76

2

75

2

77

5

35

5

57

6

56

6

58

Continuity should not exist.

PBIB2715E

EC-1030

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DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

4. 

CHECK FUEL PRESSURE

1.

Release fuel pressure to zero. Refer to 

EC-790, "FUEL PRESSURE RELEASE"

 .

2.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-791, "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-1395, "FUEL PUMP"

 .)

●

Fuel pressure regulator (Refer to 

EC-791, "FUEL PRESSURE CHECK"

 .)

●

Fuel lines

●

Fuel filter for clogging

>> Repair or replace.

6. 

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” 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 (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-906, "DTC P0101 MAF SENSOR"

 .

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

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

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7. 

CHECK FUNCTION OF FUEL INJECTOR

 With CONSULT-II

1.

Perform “POWER BALANCE” in “ACTIVE TEST” mode with
CONSULT-II.

2.

Make sure that each circuit produces a momentary engine
speed drop.

OK or NG

OK

>> GO TO 9.

NG

>> Perform trouble diagnosis for 

EC-1389, "FUEL INJECTOR"

 .

8. 

CHECK FUNCTION OF FUEL INJECTOR

 Without CONSULT-II

Listen to each fuel injector operating sound.

OK or NG

OK

>> GO TO 9.

NG

>> Perform trouble diagnosis for 

EC-1389, "FUEL INJEC-

TOR"

 .

9. 

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.

Disconnect all fuel injector harness connectors.

4.

Remove fuel tube assembly. Refer to 

EM-193, "FUEL INJECTOR AND FUEL TUBE"

 .

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

5.

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

6.

Disconnect all ignition coil harness connectors.

7.

Prepare pans or saucers under each fuel injector.

8.

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 10.

NG

>> Replace fuel injectors from which fuel does not spray

out. Always replace O-ring with new ones.

PBIB0133E

Operating sound should exist.

PBIB1986E

Fuel should be sprayed evenly for each fuel injector.

PBIB1726E

EC-1032

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DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

10. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-857, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END