Nissan Pathfinder (2007 year). Manual - part 180

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-307

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EC

2007 Pathfinder

BANK 2

BBWA2820E

EC-308

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

2007 Pathfinder

Specification data are reference values and are measured between each terminal and ground.
Pulse signal is measured by CONSULT-II.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECMs transistor. Use a ground other than ECM terminals, such as the ground.

: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

16

BR

A/F sensor 1 (Bank 2)

[Engine is running]

●

Warm-up condition

●

Engine speed: 2,000 rpm

Approximately 1.8V
Output voltage varies with air 
fuel ratio.

24
43

G
G

A/F sensor 1 heater (Bank 2)

[Engine is running]

●

Warm-up condition

●

Idle speed
(More than 140 seconds after starting 
engine)

Approximately 2.9 - 8.8V

40
41
42

V
R
O

Fuel injector No. 6
Fuel injector No. 4 
Fuel injector No. 2

[Engine is running]

●

Warm-up condition

●

Idle speed

NOTE:
The pulse cycle changes depending on 
rpm at idle

BATTERY VOLTAGE

(11 - 14V)

[Engine is running]

●

Warm-up condition

●

Engine speed: 2,000 rpm

BATTERY VOLTAGE

(11 - 14V)

75

P

A/F sensor 1 (Bank 2)

[Ignition switch: ON]

Approximately 2.2V

PBIA8148J

SEC984C

SEC985C

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-309

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Diagnostic Procedure

UBS00K7D

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

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.

PBIB1216E

EC-310

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

2007 Pathfinder

3. 

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect corresponding A/F sensor 1 harness connector.

3.

Disconnect ECM harness connector.

4.

Check harness continuity between A/F sensor 1 terminal and ECM terminal as follows.
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.

4. 

CHECK FUEL PRESSURE

1.

Release fuel pressure to zero. Refer to 

EC-79, "FUEL PRESSURE RELEASE"

 .

2.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-80, "FUEL PRESSURE CHECK"

 .

OK or NG

OK (With CONSULT-II)>>GO TO 6.
OK (Without CONSULT-II)>>GO TO 7.
NG

>> GO TO 5.

A/F sensor 1 terminal

ECM terminal

Bank 1

1

35

2

56

Bank 2

1

16

2

75

Continuity should exist.

Bank 1

Bank 2

A/F sensor 1 terminal

ECM terminal

A/F sensor 1 terminal

ECM terminal

1

35

1

16

2

56

2

75

Continuity should not exist.

BBIA0544E

At idling: 350 kPa (3.57 kg/cm

2

 , 51 psi)

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-311

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2007 Pathfinder

5. 

DETECT MALFUNCTIONING PART

Check the following.

●

Fuel pump and circuit (Refer to 

EC-637, "FUEL PUMP"

 .)

●

Fuel pressure regulator (Refer to 

EC-80, "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.

Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.

OK or NG

OK

>> GO TO 8.

NG

>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or

ground. Refer to 

EC-187

 .

7. 

CHECK MASS AIR FLOW SENSOR

 With GST

1.

Install all removed parts.

2.

Check mass air flow sensor signal in Service $01 with GST.

OK or NG

OK (P0171)>>GO TO 9.
OK (P0174)>>GO TO 11.
NG

>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or

ground. Refer to 

EC-187

 .

8. 

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.

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-312

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

2007 Pathfinder

OK or NG

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-630

 .

9. 

CHECK FUNCTION OF FUEL INJECTOR-I

 Without CONSULT-II

1.

Stop engine.

2.

Disconnect harness connector F44, F101

3.

Turn ignition switch ON.

4.

Check voltage between harness connector F44 terminal 3 and
ground with CONSULT-II or tester.

5.

Turn ignition switch OFF.

6.

Disconnect ECM harness connector.

7.

Check harness continuity between harness connector F44 and
ECM as follows.
Refer to Wiring Diagram.

8.

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

OK or NG

OK

>> GO TO 10.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-630

 .

BBIA0587E

Voltage: Battery voltage

Cylinder

Harness connector F44 

terminal

ECM terminal

1

2

23

3

1

22

5

4

21

Continuity should exist.

PBIB2633E

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

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10. 

CHECK FUNCTION OF FUEL INJECTOR-II

Provide battery voltage between harness connector F101 as follows
and then interrupt it. Listen to each fuel injector operating sound.

OK or NG

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to 

EC-630

 .

11. 

CHECK FUNCTION OF FUEL INJECTOR

1.

Start engine.

2.

Listen to fuel injectors No.2, No.4, No.6 operating sound.

OK or NG

OK

>> GO TO 12.

NG

>> Perform trouble diagnosis for FUEL INJECTOR, refer to

EC-630

 .

12. 

CHECK FUEL INJECTOR

1.

Confirm that the engine is cooled down and there are no fire hazards near the vehicle.

2.

Turn ignition switch OFF.

3.

Disconnect all injector harness connectors.

4.

Remove fuel tube assembly. Refer to 

EM-35, "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 13.

NG

>> Replace fuel injectors from which fuel does not spray

out. Always replace O-ring with new ones.

Cylinder

Harness connector F101 terminal

(+)

(–)

1

3

2

3

3

1

5

3

4

Operating sound should exist.

PBIB2634E

Clicking noise should exist.

PBIB1986E

Fuel should be sprayed evenly for each fuel injector.

PBIB1726E

EC-314

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

2007 Pathfinder

13. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-145, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END