Isuzu Trooper (1998-2002 year). Manual - part 633

6E–180

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Surges and/or Chuggles Symptom

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

1. Check the exhaust system for possible restriction:

D

Inspect the exhaust system for damaged or
collapsed pipes.

D

Inspect the muffler for heat distress or possible
internal failure.

D

Check for a possible plugged catalytic
converter by checking the exhaust system
back pressure.  Refer to 

Restricted Exhaust

System Check.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 11

11

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

D

Visual/physical inspection

D

Tech 2 data

D

Freeze Frame data/Failure Records buffer

D

All electrical connections within a suspected
circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Contact

Technical

Assistance

6E–181

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Lack of Power, Sluggish or Spongy Symptom

 

Step

Action

Value(s)

Yes

No

1

DEFINITION:
Engine delivers less than expected power.  Little or no
increase in speed when accelerator pedal is pushed
down part-way.

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

—

Verify repair

Go to 

Step 3

3

Was a visual/physical check performed?

—

Go to 

Step 4

Go to 

Visual/

Physical

Check

4

1. Remove and check the air filter element for dirt or

restrictions.  Refer to 

Air Intake System in

On-Vehicle Service.

2. Replace the air filter element if necessary.

Was a repair required?

—

Verify repair

Go to 

Step 5

5

1. Check AP sensor system.  Refer to 

AP sensor

diagnostic.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 6

6

1. Check for water-or alcohol-contaminated fuel.
2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 7

7

1. Using a Tech 2, Injector test.
2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 8

8

1. Check the ECM grounds for the cleanliness,

tightness and proper locations.  Refer to the ECM
wiring diagrams in 

Electrical Diagnosis.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 9

9

1. Check the exhaust system for possible restriction:

D

Inspect the exhaust system for damaged or
collapsed pipes.

D

Inspect the muffler for heat distress or possible
internal failure.

D

Check for a possible plugged catalytic
converter by checking the exhaust system
back pressure.  Refer to 

Restricted Exhaust

System Check.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 10

10

1. Check the torque converter clutch (TCC) for proper

operation.  Refer to 

Transmission Diagnosis.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 11

6E–182

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Lack of Power, Sluggish or Spongy Symptom

  (Cont'd)

Step

No

Yes

Value(s)

Action

11

1. Check for an engine mechanical problem.  Check

for low compression, incorrect or worn camshaft,
loose timing belt, etc.  Refer to 

Engine Mechanical.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 12

12

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

D

Visual/physical inspection

D

Tech 2 data

D

Freeze Frame data/Failure Records buffer

D

All electrical connections within a suspected
circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Contact

Technical

Assistance

6E–183

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

 

Step

Action

Value(s)

Yes

No

1

DEFINITION:
Engine runs unevenly at idle.  If severe, the engine or
vehicle may shake.  Engine idle speed may vary in
RPM.   Either condition may be severe enough to stall
the engine.

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

—

Go to 

Step 6

Go to 

Step 3

3

Was a visual/physical check performed?

—

Go to 

Step 4

Go to 

Visual/

Physical

Check

4

1. Check the ECM grounds for cleanliness, tightness

and proper routing.  Refer to the ECM wiring
diagrams in 

Electrical Diagnosis.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step  5

5

1. Check for incorrect idle speed.  Ensure that the

following conditions are present:

D

The engine is fully warm.

D

The accessories are “OFF.”

2. Using a Tech 2, monitor the AP position.

Is the AP position within the specified values?

0%

Go to 

Step 10

Go to 

Step 9

6

1. Visually/physically inspect for the following

conditions:

D

Restricted air intake system.  Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to 

Step 7

7

1. Injector Test

Operate the each injector by Tech 2 with the
ignition “ON” and check if the working noise
confirm.

2. If a problem is found, check the harness or replace

the injector.

Is the action complete?

—

Verify repair

Go to 

Step 8

8

1. Check the transmission range switch circuit.  Use a

Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.

2. If a problem is found, diagnose and repair the

transmission range switch as necessary (Refer to
Automatic Transmission Diagnosis).

Was a problem found?

—

Verify repair

Go to 

Step 9