Nissan Xterra. Manual — part 254

EC-142

< DTC/CIRCUIT DIAGNOSIS >

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TROUBLE DIAGNOSIS - SPECIFICATION VALUE

JMBIA1468GB

TROUBLE DIAGNOSIS - SPECIFICATION VALUE

EC-143

< DTC/CIRCUIT DIAGNOSIS >

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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-141, "Testing Condition"

.

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

indication is within the SP value.

NOTE:

PBIB3214E

EC-144

< DTC/CIRCUIT DIAGNOSIS >

[VQ40DE]

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 check 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 check 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 check 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-494, "Fuel Pressure Check"

.)

OK or NG

OK

>> GO TO 9.

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

EC-494, "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-467, "Description"

.)

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

If OK, replace fuel pressure regulator. Refer to

FL-11, "Removal and Installation"

.

TROUBLE DIAGNOSIS - SPECIFICATION VALUE

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>> GO TO 8.

8.

CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”

1. Start engine.

2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and check that each

indication is within the SP value.

OK or NG

OK

>> INSPECTION END

NG

>> GO TO 9.

9.

PERFORM POWER BALANCE TEST

1. Perform “POWER BALANCE” in “ACTIVE TEST” mode.

2. Check that the each cylinder produces a momentary engine speed drop.
OK or NG

OK

>> GO TO 12.

NG

>> GO TO 10.

10.

DETECT MALFUNCTIONING PART

1. Check the following below.

-

Ignition coil and its circuit (Refer to

EC-470, "Component Description"

.)

-

Fuel injector and its circuit (Refer to

EC-463, "Component Description"

.)

-

Intake air leakage

-

Low compression pressure (Refer to

EM-22, "Compression Pressure"

.)

2. If NG, repair or replace the malfunctioning part.

If OK, replace fuel injector. (It may be caused by leakage from fuel injector or clogging.) Refer to

EM-45,

"Exploded View"

.

>> GO TO 11.

11.

CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”

1. Start engine.

2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and check that each

indication is within the SP value.

OK or NG

OK

>> INSPECTION END

NG

>> GO TO 12.

12.

CHECK A/F SENSOR 1 FUNCTION

Perform all DTC Confirmation Procedure related with A/F sensor 1.

• For DTC P0130, P0150, refer to

EC-200, "DTC Confirmation Procedure"

.

• For DTC P0131, P0151, refer to

EC-204, "DTC Confirmation Procedure"

.

• For DTC P0132, P0152, refer to

EC-207, "DTC Confirmation Procedure"

.

• For DTC P014C, P014D, P014E, P014F, P015A, P015B, P015C, P015D, refer to

EC-229, "DTC Logic"

.

• For DTC P2096, P2097, P2098, P2099 refer to

EC-420, "DTC Confirmation Procedure"

.

OK or NG

OK

>> GO TO 15.

NG

>> GO TO 13.

13.

CHECK A/F SENSOR 1 CIRCUIT

Perform Diagnostic Procedure according to corresponding DTC.

>> GO TO 14.

14.

CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”

1. Start engine.

2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and check that each

indication is within the SP value.