Nissan Frontier. Manual - part 509

TROUBLE DIAGNOSIS - SPECIFICATION VALUE

EC-607

< DTC/CIRCUIT DIAGNOSIS >

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DTC/CIRCUIT DIAGNOSIS

TROUBLE DIAGNOSIS - SPECIFICATION VALUE

Description

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The specification (SP) value indicates the tolerance of the value that is displayed in “SPEC” of “DATA MONI-

TOR” mode of CONSULT during normal operation of the Engine Control System. When the value in “SPEC” of

“DATA MONITOR” mode is within the SP value, the Engine Control System is confirmed OK. When the value

“SPEC” of “DATA MONITOR” mode is NOT within the SP value, the Engine Control System may have one or

more malfunctions.

The SP value is used to detect malfunctions that may affect the Engine Control System, but will not illuminate

the MIL.

The SP value will be displayed for the following three items:

• B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board correc-

tion)

• A/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)

• MAS A/F SE-B1 (The signal voltage of the mass air flow sensor)

Testing Condition

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• Vehicle driven distance: More than 5,000 km (3,107 miles)
• Barometric pressure: 98.3 - 104.3 kPa (1.003 - 1.064 kg/cm

2

, 14.25 - 15.12 psi)

• Atmospheric temperature: 20 - 30

°C (68 - 86°F)

• Engine coolant temperature: 75 - 95

°C (167 - 203°F)

• Transmission: Warmed-up*

1

• Electrical load: Not applied*

2

• Engine speed: Idle

*1: After the engine is warmed up to normal operating temperature, drive vehicle until “FLUID TEMP SE” (A/T

fluid temperature sensor signal) indicates more than 60

°C (140°F).

*2: Rear window defogger switch air conditioner switch, lighting switch are OFF. Steering wheel is straight

ahead.

Inspection Procedure

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NOTE:

Perform “SPEC” of “DATA MONITOR” mode in maximum scale display.
1. Perform 

EC-584, "Basic Inspection"

.

2. Confirm that the testing conditions indicated above are met.
3. Select “B/FUEL SCHDL”, “A/F ALPHA-B1”, “A/F ALPHA-B2” and “MAS A/F SE-B1” in “SPEC” of “DATA

MONITOR” mode with CONSULT.

4. Make sure that monitor items are within the SP value.
5. If NG, go to 

EC-607, "Diagnosis Procedure"

.

Diagnosis Procedure

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OVERALL SEQUENCE

EC-608

< DTC/CIRCUIT DIAGNOSIS >

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TROUBLE DIAGNOSIS - SPECIFICATION VALUE

JMBIA1468GB

TROUBLE DIAGNOSIS - SPECIFICATION VALUE

EC-609

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DETAILED PROCEDURE

1.

CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”

1. Start engine.

2. Confirm that the testing conditions are met. Refer to 

EC-607, "Testing Condition"

.

3. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that

each indication is within the SP value.

NOTE:

PBIB3214E

EC-610

< DTC/CIRCUIT DIAGNOSIS >

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TROUBLE DIAGNOSIS - SPECIFICATION VALUE

Check “A/F ALPHA-B1”, “A/F ALPHA-B2” for approximately 1 minute because they may fluctuate. It is NG

if the indication is out of the SP value even a little.

OK or NG

OK

>> GO TO 17.

NG (Less than the SP value)>>GO TO 2.

NG (More than the SP value)>>GO TO 3.

2.

CHECK “B/FUEL SCHDL”

Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the

SP value.
OK or NG

OK

>> GO TO 4.

NG (More than the SP value)>>GO TO 19.

3.

CHECK “B/FUEL SCHDL”

Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the

SP value.
OK or NG

OK

>> GO TO 6.

NG (More than the SP value)>>GO TO 6.

NG (Less than the SP value)>>GO TO 25.

4.

CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”

1. Stop the engine.

2. Disconnect PCV hose, and then plug it.

3. Start engine.

4. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that

each indication is within the SP value.

OK or NG

OK

>> GO TO 5.

NG

>> GO TO 6.

5.

CHANGE ENGINE OIL

1. Stop the engine.

2. Change engine oil.

NOTE:

This symptom may occur when a large amount of gasoline is mixed with engine oil because of driving

conditions (such as when engine oil temperature does not rise enough since a journey distance is too

short during winter). The symptom will not be detected after changing engine oil or changing driving con-

ditions.

>> INSPECTION END

6.

CHECK FUEL PRESSURE

Check fuel pressure. (Refer to 

EC-959, "Fuel Pressure Check"

.)

OK or NG

OK

>> GO TO 9.

NG (Fuel pressure is too high)>>Replace fuel pressure regulator, refer to 

EC-959, "Fuel Pressure Check"

.

GO TO 8.

NG (Fuel pressure is too low)>>GO TO 7.

7.

DETECT MALFUNCTIONING PART

1. Check the following.

-

Clogged and bent fuel hose and fuel tube

-

Clogged fuel filter

-

Fuel pump and its circuit (Refer to 

EC-932, "Description"

.)

2. If NG, repair or replace the malfunctioning part. (Refer to Diagnosis Procedure.)

If OK, replace fuel pressure regulator.