Infiniti Q45. Manual - part 421

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-323

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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.

PBIB3134E

EC-324

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

4. 

CHECK FUEL PRESSURE

1.

Release fuel pressure to zero. Refer to 

EC-80, "FUEL PRESSURE RELEASE"

 .

2.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-80, "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-534, "DTC P1220 FUEL PUMP CONTROL MODULE (FPCM)"

 , 

EC-

715, "FUEL PUMP"

 .)

●

Fuel pressure regulator (Refer to 

EC-80, "FUEL PRESSURE CHECK"

 .)

●

Fuel lines (Refer to 

MA-15, "Checking 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.

 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-195, "DTC P0101 MAF SENSOR"

 .

At idling: 350 kPa (3.57 kg/cm

2

 , 51 psi)

3.8 - 5.2 g·m/sec:

at idling

16.0 - 21.5 g·m/sec:

at 2,500 rpm

3.8 - 5.2 g·m/sec:

at idling

16.0 - 21.5 g·m/sec:

at 2,500 rpm

DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-325

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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 

EC-706, "FUEL INJECTOR"

 .

PBIB0133E

EC-326

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 F21, F201 (bank 1) and F41, F221 (bank 2).

3.

Turn ignition switch ON.

4.

Check voltage between the following;
harness connector F21 terminal 5 and ground,
harness connector F41 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 

EC-706, "FUEL INJECTOR"

 .

Voltage: Battery voltage

Cylinder

Harness connector terminal

ECM terminal

1

F21 terminal 3

23

3

F21 terminal 2

22

5

F21 terminal 1

21

7

F21 terminal 6

44

2

F41 terminal 3

42

4

F41 terminal 2

41

6

F41 terminal 1

40

8

F41 terminal 6

63

Continuity should exist.

PBIB2438E

PBIB0180E