check engine ISUZU TROOPER 1998 Service Repair Manual

6E±185 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Fuel economy, as measured by an actual road test, is
noticeably lower than expected. Also, economy is
noticeably lower than it was on this vehicle at one time,
as previously shown by an actual road test. (Larger than
standard tires will cause odometer readings to be
incorrect, and that may cause fuel economy to appear
poor when it is actually normal.)
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
4Check owner's driving habits.

Is the A/C ªONº full time (defroster mode ªONº)?

Are tires at the correct pressure?

Are excessively heavy loads being carried?

Is acceleration too much, too often?

Is engine oil correct?
Was a problem found?
ÐGo to Step 5Go to Step 6
5Review the items in Step 4 with the customer and
advise as necessary.
Is the action complete?
ÐSystem OKÐ
61. Visually/physically check: Vacuum hoses for splits,
kinks, and improper connections and routing as
shown on the ªVehicle Emission Control
Informationº label.
2. If a problem is found, repair as necessary.
Was a repair required?
ÐVerify repairGo to Step 7
71. Remove and check the air filter element for dirt or for
restrictions. Refer to
Air Intake System.
2. Replace the air filter element if necessary.
Was a repair required?
ÐVerify repairGo to Step 8
81. Check for low engine coolant level. Refer to Engine
Cooling
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Check for an incorrect or faulty engine thermostat.
Refer to
Engine Cooling.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
101. Check for low engine compression. Refer to Engine
Mechanical
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11

6E±186
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

 
StepNo Ye s Value(s) Action
111. Check the TCC operation. Refer to Transmission
Diagnosis
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Check the exhaust system for possible restriction:

Inspect the exhaust system for damaged or
collapsed pipes.

Inspect the muffler for heat distress or possible
internal failure.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
13Check for proper calibration of the speedometer.
Does the speed indicated on the speedometer closely
match the vehicle speed displayed on the Tech 2?
ÐGo to Step 15Go to Step 14
14Diagnose and repair an inaccurate speedometer
condition as necessary. Refer to
Vehicle Speed
Sensor
in Electrical Diagnosis.
Was a problem found?
ÐVerify repairÐ
151. Check the air intake system and the crankcase for
air leaks. Refer to
Air Intake System and
Crankcase Ventilation System.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 16
161. Review all diagnostic procedures within this table.
2. When all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All connections within a suspected circuit
and/or system.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 17
17Perform the procedure in Injector Test.
Was the fuel pressure normal?
Ð
Contact
Technical
Assistance
Verify repair

6E±187 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Excessive Exhaust Emissions or Odors Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Vehicle fails an emission test. Vehicle has excessive
ªrotten eggº smell. (Excessive odors do not necessarily
indicate excessive emissions.)
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a thorough visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Check for vacuum leaks. Check vacuum lines,
intake manifold, throttle body, etc.
2. If a problem is found, repair as necessary.
Were any vacuum leaks located?
ÐVerify repairGo to Step 5
51. Check the fuel cap for proper installation.
2. Secure the fuel cap if necessary.
Was the fuel cap installed properly?
ÐGo to Step 6Verify repair
61. Injector Test
Operate the each injector by Tech 2 with the
ignition ªONº and check if the working noise
confirm.
2. If a problem is found, check the harness or replace
the injector.
Is the action complete?
ÐVerify repairGo to Step 7
71. Refer to Engine Cooling for cooling system
diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check for an engine mechanical problem.
Perform a cylinder compression check (Refer to
Engine Mechanical).
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±188
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Dieseling, Run-On Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Engine continues to run after key is turned ªOFF,º but
runs very rough. If engine runs smooth, check ignition
switch and adjustment.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Check for a short between B+ and any of the ignition
feed circuits.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±189 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Symptom

StepActionValue(s)Ye sNo
1DEFINITION:
Steady pulsation or jerking that follows engine speed;
usually more pronounced as engine load increases.
Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. 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?
ÐGo to Step 7Go to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
41. Check the ECM grounds for clearness, 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?
ÐVerify repairGo to Step 5
51. Check for incorrect idle speed. Ensure that the
following conditions are present:

The engine is fully warm.

The accessories are ªoff.º
2. Using a Tech 2, monitor the AP position.
Is the AP position within the specified values?
0%Go to Step 6Go to Step 7
61. Visually/physically inspect for the following
conditions:

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

Check the Throttle body.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty VSV or brake
booster hose disconnected .
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
7Using a Tech 2, monitor the AP angle with the engine
idling.
Is the AP angle at the specified value and steady?
0%Go to Step 8
Refer to DTC
P0123
for
further
diagnosis
81. 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.
Was a problem found?
ÐVerify repairGo to Step 9

6E±190
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Symptom

 
StepNo Ye s Value(s) Action
91. Injector Test
Operate the each injector by Tech 2 with the
ignition ªONº and check if the working noise
confirm.
2. If a problem is found, check the harness or replace
the injector.
Is the action complete?
ÐVerify repairGo to Step 10
101. Check the following engine mechanical items.
Refer to
Engine Mechanical for diagnosis
procedures:

Low compression

Sticking or leaking valves

Worn camshaft lobe(s)

Camshaft drive belt slipped or stripped

Incorrect valve timing

Broken valve springs
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11
111. Check for faulty motor mounts. Refer to Engine
Mechanical
for inspection of mounts.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±191 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Starter Motor Doesn't Rotate

StepActionValue(s)Ye sNo
1DEFINITION:
As starter motor doesn't rotate, engine is not cranked.
1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was the bulletin found?
ÐVerify repairGo to Step 2
2Was a visual/physical check performed?
ÐGo to Step 3
Go to Visual/
Physical
Check
31. Check battery cord terminal for looseness & poor
contact due to corrosion.
2. Check battery voltage.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 4
41. Check fan belt for looseness & damage.
2. If a problem is found, adjust or replace as
necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check fuse bull link for disconnection & short.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Check generator for mount & damage (Refer to
Engine Mechanical).
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check starter SW and starter relay for looseness
and damage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check starter motor for mount and damage. (Refer
to
Engine Mechanical)
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance

6E±192
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Starting Difficulty In Case Fuel Doesn't Come to Injector

StepActionValue(s)Ye sNo
1DEFINITION:
Engine is cranked, but not started for a long time. Steps
soon.
Was OBD System check performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin research.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found?
ÐVerify repairGo to Step 3
3Was a visual/physical check performed?
ÐGo to Step 4
Go to Visual/
Physical
Check
4Check fuel shortage. If short, replenish.
Was fuel short?
Ð
Verify
replenish
Go to Step 5
51. Check fuel pipeline for leak.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Check fuel pipeline & filter for deformation &
clogging.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check fuel pump for damage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
8Check the Injector test by Tech 2.
Does the working noise confirm?
ÐGo to Step 11Go to Step 9
91. Check the injector connector for damage.
2. Check the injector harness for damage.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
10Replace the injector. (Refer to the injector group sign
programming)
Is the action complete?ÐVerify repairÐ
111. Indicate RPCV Data List by Tech 2 to check
operation. Perform RPCV test.
2. If a problem is found, replace RP sensor or RPCV
as necessary.
Was a problem found?
ÐVerify repairGo to Step 12

6E±194
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Lubrication System Trouble

StepActionValue(s)Ye sNo
1DEFINITION:
In road tests oil pressure doesn't rise, or oil is foul to
excess.
Was OBD System check performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Perform a bulletin research.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found?
ÐVerify repairGo to Step 3
31. Check if a correct engine oil is used.
2. If a problem is found, change engine oil.
Was a problem found?
ÐVerify repairGo to Step 4
41. Check the oil pressure meter for damage.
2. Check the oil unit harness and connector for
damage.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Check oil pipe connections for leakage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 6
61. Check oil filter for clogging.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 7
71. Check valve clearance.
2. If a problem is found, adjust as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Check camshaft bearing for wear.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Check crankshaft & connecting rod bearings for
wear.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 10
101. Check oil pump for damage.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 11

6E±195 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Lubrication System Trouble

 
StepNo Ye s Value(s) Action
111. Check cylinder head & cam carrier gaskets for
damage.
2. If a problem is found, repair or replace as
necessary.
Was a problem found?
ÐVerify repairGo to Step 12
121. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records butter

All electrical connections within a suspected
circuit and/or system
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repair
Contact
Technical
Assistance