Nissan Frontier D22. Manual - part 430

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-823

[VG33E]

C

D

E

F

G

H

I

J

K

L

M

A

EC

BANK 2

BBWA1083E

EC-824

[VG33E]

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

Diagnostic Procedure

UBS00DIT

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 FOR PCV HOSE

Check PCV hose for loose connection or disconnection.

OK or NG

OK

>> GO TO 4.

NG

>> Repair or replace.

SEC502D

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-825

[VG33E]

C

D

E

F

G

H

I

J

K

L

M

A

EC

4. 

CHECK HEATED OXYGEN SENSOR 1 CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect corresponding heated oxygen sensor 1 harness connector.

3.

Disconnect ECM harness connector.

4.

Check harness continuity between ECM terminal and HO2S1 terminal as follows.
Refer to Wiring Diagram.

5.

Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows.
Refer to Wiring Diagram.

6.

Also check harness for short to power.

OK or NG

OK

>> GO TO 5.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

5. 

CHECK FUEL PRESSURE

1.

Release fuel pressure to zero.
Refer to 

EC-616, "FUEL PRESSURE RELEASE"

 .

2.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-617, "FUEL PRESSURE CHECK"

 .

OK or NG

OK

>> GO TO 7.

NG

>> GO TO 6.

6. 

DETECT MALFUNCTIONING PART

Check the following.

●

Fuel pump and circuit (Refer to 

EC-1149

 .)

●

Fuel pressure regulator (Refer to 

EC-617

 .)

●

Fuel lines (Refer to 

MA-28, "Checking Fuel Lines"

 .)

●

Fuel filter for clogging

>> Repair or replace.

DTC

Terminals

Bank

ECM

Sensor

P0171

50

2

Bank 1 

P0174

51

2

Bank 2

Continuity should exist. 

DTC

Terminals

Bank

ECM or sensor

Ground

P0171

50 or 2

Ground

Bank 1 

P0174

51 or 2

Ground

Bank 2

Continuity should not exist.

At idling:

When fuel pressure regulator valve 
vacuum hose is connected.

235 kPa (2.4 kg/cm

2

 , 34 psi)

When fuel pressure regulator valve 
vacuum hose is disconnected.

294 kPa (3.0 kg/cm

2

 , 43 psi)

EC-826

[VG33E]

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

7. 

CHECK MASS AIR FLOW SENSOR

 With CONSULT-II 

1.

Install all parts removed.

2.

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

 With GST

1.

Install all parts removed.

2.

Check mass air flow sensor signal in MODE 1 with GST.

OK or NG

OK

>> GO TO 8.

NG

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

engine grounds. Refer to 

EC-720

 .

8. 

CHECK FUNCTION OF INJECTORS

 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.

 Without CONSULT-II

1.

Start engine.

2.

Listen to each injector operating sound.

OK or NG

OK

>> GO TO 9.

NG

>> Perform trouble diagnosis for 

EC-1140, "INJECTOR CIRCUIT"

 .

3.3 - 4.8 g·m/sec

: at idling

12.0 - 14.9 g·m/sec

: at 2,500 rpm

3.3 - 4.8 g·m/sec

: at idling

12.0 - 14.9 g·m/sec

: at 2,500 rpm

SEF070Y

Clicking noise should be heard.

MEC703B