Nissan Frontier D22. Manual - part 283

DTC P0172 FUEL INJECTION SYSTEM FUNCTION

EC-235

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Diagnostic Procedure

UBS00D58

1. 

 CHECK FOR 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 HEATED OXYGEN SENSOR 1 CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect heated oxygen sensor 1 harness connector and
ECM harness connector.

3.

Check harness continuity between ECM terminal 50 and HO2S1
terminal 2.
Refer to Wiring Diagram.

4.

Check harness continuity between ECM terminal 50 or HO2S1
terminal 2 and ground.
Refer to Wiring Diagram.

5.

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

OK or NG

OK

>> GO TO 3.

NG

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

3. 

CHECK FUEL PRESSURE

1.

Release fuel pressure to zero.
Refer to 

EC-46, "FUEL PRESSURE RELEASE"

 .

2.

Install fuel pressure gauge and check fuel pressure.

OK or NG

OK

>> GO TO 5.

NG

>> GO TO 4.

SEC502D

Continuity should exist.

Continuity should not exist.

BBIA0430E

At idling

When fuel pressure regulator valve 
vacuum hose is connected.

Approximately 235 kPa (2.4 kg/cm

2

 , 34 psi)

When fuel pressure regulator valve 
vacuum hose is disconnected.

Approximately 294 kPa (3.0 kg/cm

2

 , 43 psi)

EC-236

[KA24DE]

DTC P0172 FUEL INJECTION SYSTEM FUNCTION

4. 

DETECT MALFUNCTIONING PART

Check the following.

●

Fuel pump and circuit (Refer to 

EC-548

 .)

●

Fuel pressure regulator (Refer to 

EC-48

 .)

>> Repair or replace.

5. 

CHECK MASS AIR FLOW SENSOR

Refer to 

EC-238, "Component Inspection"

 .

OK or NG

OK

>> GO TO 6.

NG

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

engine grounds. Refer to 

EC-143, "DTC P0102, P0103 MAF SENSOR"

 .

6. 

CHECK FUNCTION OF INJECTORS

 With CONSULT-II

1.

Install all parts removed.

2.

Start engine.

3.

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

4.

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

 Without CONSULT-II

1.

Install all parts removed.

2.

Start engine.

3.

Listen to each injector operating sound.
Clicking noise should be heard.

OK or NG

OK

>> GO TO 7.

NG 

>> Perform trouble diagnosis for injectors, 

EC-539, "INJEC-

TOR CIRCUIT"

 .

7. 

REMOVE INJECTOR

1.

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

2.

Turn ignition switch OFF.

3.

Remove injector assembly.
Keep fuel hose and all injectors connected to injector gallery.

>> GO TO 8.

SEF981Z

MEC703B

DTC P0172 FUEL INJECTION SYSTEM FUNCTION

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8. 

CHECK INJECTOR

Refer to 

EC-238, "Component Inspection"

 .

OK or NG

OK (Does not drip)>>GO TO 9.
NG (Drips)>>Replace the injectors from which fuel is dripping. Always replace O-ring with new one.

9. 

CHECK INTERMITTENT INCIDENT

Perform 

EC-120, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END.

EC-238

[KA24DE]

DTC P0172 FUEL INJECTION SYSTEM FUNCTION

Component Inspection

UBS00D59

MASS AIR FLOW SENSOR

 With CONSULT-II

1.

Start engine and warm it up to normal operating temperature.

2.

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

 With GST

1.

Start engine and warm it up to normal operating temperature.

2.

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

INJECTOR

1.

Disconnect all injector harness connectors.

2.

Disconnect all ignition coil harness connectors.

3.

Prepare pans or saucers under each injectors.

4.

Crank engine for about 3 seconds.
Make sure fuel does not drip from injector.

at idling

: 0.9 - 5.8 g·m/sec

at 2,500 rpm

: 7.5 - 13.2 g·m/sec

 at idling

: 0.9 - 5.8 g·m/sec

at 2,500 rpm

: 7.5 - 13.2 g·m/sec