1998 ISUZU TROOPER 6b engine cooling

6E±275 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.
(Non-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/Physic
al 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?
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 problem found?
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. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Spark Plug Replacement.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. 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 10

6E±276
ENGINE DRIVEABILITY AND EMISSIONS
Poor Fuel Economy Symptom

 
StepNo Ye s Value(s) Action
101. 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 11
111. 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 12
121. Check the TCC operation. Refer to 4L30-E
Transmission Diagnosis
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 13
131. 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.

Check for a possible plugged three-way
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?
ÐVerify repairGo to Step 14
14Check for proper calibration of the speedometer.
Does the speed indicated on the speedometer closely
match the vehicle speed displayed on Tech 2?
ÐGo to Step 16Go to Step 15
15Diagnose and repair an inaccurate speedometer
condition as necessary. Refer to
Vehicle Speed
Sensor
in Electrical Diagnosis.
Was a problem found?
ÐVerify repairÐ
161. 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 17
171. 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 18
18Perform the procedure in Fuel System Pressure Test.
Was the fuel pressure normal?
Ð
Contact
Technical
Assistance
Verify repair

6E±277 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?
ÐGo to Step 12Go to Step 3
3Was a thorough visual/physical check performed?
ÐGo to Step 4
Go to
Visual/Physic
al 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?
ÐGo to Step 12Go 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 6Go to Step 12
61. Check the fuel pressure. Perform the procedure in
Fuel System Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 7
71. Check for a faulty, plugged, or incorrectly installed
crankcase ventilation valve; also check the
crankcase ventilation system for plugging.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 8
81. Check the injector connections.
2. If any of the injectors are connected to an incorrect
cylinder, correct as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 9
91. Perform the ªInjector Coil/Balance Testº in Fuel
Metering System
.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 10
101. Refer to Engine Cooling for cooling system
diagnosis.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 12Go to Step 11
111. Remove excessive carbon buildup with a top engine
cleaner. Refer to the instructions on the top engine
cleaner can.
2. Perform the exhaust emission test.
Does the vehicle pass the test?
ÐSystem OKGo to Step 13
12Perform the exhaust emission test.
Does the vehicle pass the test?
ÐSystem OKGo to Step 13

6E±289 ENGINE DRIVEABILITY AND EMISSIONS
Symptoms Default Section(s)Initial Diagnosis
Lack of Power, Sluggish or Spongy1. OBD system check.
2. Fuel system diagnosis.
3. Ignition system.
4. Knock sensor.
5. EGR operation.
6. EGR system check.Refer to Exhaust System in
Engine Exhaust, TCC Operation,
Calibration ID/Service Bulletins
Detonation/Spark Knock1. OBD system check.
2. Transmission range switch.
3. EGR operation.
4. EGR system check.
5. TCC operation.
6. Fuel system diagnosis.
7. Ignition system.
8. Knock sensor.TCC operation, Cooling System,
Ignition System Check,
Calibration ID/Service Bulletins
Hesitation, Sag, Stumble1. OBD system check.
2. TP.
3. MAP output check.
4. Fuel system diagnosis.
5. Fuel injector and fuel injector
balance test.
6. Ignition system.EGR Operation, EGR System
Check, Generator Output
Voltage (refer to
Chassis
Electrical
), Calibration ID/Service
Bulletins, Ignition System Check
Cuts Out, Misses1. OBD system check.
2. Cylinder balance test.Ignition System Check
Rough, Unstable, or Incorrect Idle,
Stalling1. OBD system check.
2. Fuel injector and fuel injector
balance test.
3. Ignition system.
4. IAC operation.
5. EGR operation.MAP Output Check, Throttle
Linkage, IAC System Check,
EGR System Check, A/C Clutch
Control Circuit Diagnosis,
Crankcase Ventilation System,
Calibration ID/Service Bulletins,
Generator Output Voltage (refer
to
Chassis Electrical), Exhaust
Diagnosis
Poor Fuel Economy1. OBD system check.
2. Careful visual/physical inspection.
3. Ignition system.
4. Cooling system.TCC Operation, Exhaust System
(refer to
Engine Exhaust)
Engine Cranks But Will Not Run1. OBD system check.Fuel System Electrical
Diagnosis, Fuel System
Diagnosis, Fuel Injector and Fuel
Injector Balance Test.
Excessive Exhaust Emissions or
Odors1. OBD system check.
2. Emission test.
3. Cooling system.
4. Fuel system diagnosis.
5. Fuel injector and fuel injector
balance test.
6. Crankcase ventilation system.
7. Ignition system.
8. MAP output check.EGR System Check, Exhaust
Diagnosis, Calibration ID/Service
Bulletins
Dieseling, Run-On1. OBD system check.
2. Careful visual/physical inspection.
3. Fuel system diagnosis.Ð

6E±292
ENGINE DRIVEABILITY AND EMISSIONS
Crankshaft Position (CKP)
Sensor
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical connector to the CKP
sensor.
3. Remove one bolt and the CKP sensor from the right
side of the engine block, just behind the mount.
NOTE: Use caution to avoid any hot oil that might drip
out.
TS22909
Inspection Procedure
1. Inspect the sensor O-ring for cracks or leaks.
2. Replace the O-ring if it is worn or damaged.
3. Lubricate the new O-ring with engine oil.
4. Install the lubricated O-ring.
Installation Procedure
1. Install the CKP sensor in the engine block.
2. Install the CKP sensor mounting bolt.
Tighten

Tighten the mounting bolt to 9 N´m (78 lb in.).
TS22909
3. Connect the electrical connector to the CKP sensor.
4. Connect the negative battery cable.
Engine Coolant Temperature
(ECT) Sensor
Removal Procedure
NOTE: Care must be taken when handling the engine
coolant temperature (ECT) sensor. Damage to the ECT
sensor will affect proper operation of the fuel injection
system.
1. Disconnect the negative battery cable.
2. Drain the radiator coolant. Refer to
Draining and
Refilling Cooling System
in Engine Cooling.
3. Disconnect the electrical connector.
014RW127

6E±293 ENGINE DRIVEABILITY AND EMISSIONS
4. Remove the ECT sensor from the coolant crossover.
014RW086
Installation Procedure
1. Apply sealer or the equivalent to the threads of the
ECT sensor.
2. Install the ECT sensor in the coolant crossover.
Tighten

Tighten the ECT sensor to 30 N´m (22 lb ft.).
014RW086
3. Connect the electrical connector.
014RW085
4. Fill the radiator with coolant. Refer to Draining and
Refilling Cooling System
in Engine Cooling.
5. Connect the negative battery cable.
Heated Oxygen Sensor (HO2S)
Removal Procedure
1. Disconnect the negative battery cable.
2. Locate the oxygen sensors.

Bank 1 sensor 1 is mounted on the right-hand front
exhaust pipe.
TS22912

6E±296
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor (KS)
Removal Procedure
1. Disconnect the negative battery cable.
2. Drain the cooling system. Refer to
Draining and
Filling the Cooling System
in Engine Cooling.
3. Remove the engine cover.
4. Remove the common chamber assembly.
Refer to Common Chamber in Engine Mechanical.
014RW106
5. Disconnect the electrical connector from the knock
sensor.
014RW103
6. Unscrew the knock sensor from the engine block.
Installation Procedure
NOTE: Do not apply thread sealant to the sensor threads.
The sensor is coated at the factory and applying
additional sealant will affect the sensor's ability to detect
detonation.
1. Screw the knock sensor into the engine block.
Tighten

Tighten the knock sensor to 20 N´m (177 lb in.).
014RW103
2. Connect the electrical connector to the knock sensor.
3. Install the common chamber assembly.
Refer to Common Chamber in Engine Mechanical.
014RW106
4. Install the engine cover.
5. Fill the cooling system.
Refer to Draining and Filling the Cooling System in
Engine Cooling.
6. Connect the negative battery cable.

6E±323 ENGINE DRIVEABILITY AND EMISSIONS
11. Connect the fuel filler fuse at the tank.
12. Connect the air breather hose at the tank.
TS23796
13. Fill the fuel tank with fuel.
14. Tighten the fuel filler cap.
15. Connect the negative battery cable.
Throttle Body (TB)
Removal Procedure
1. Disconnect the negative battery cable.
2. Drain the cooling system. Refer to
Cooling System.
3. Remove the accelerator cable assembly. Refer to
Accelerator Cable in Engine Speed Control System..
4. Disconnect the electrical connectors:

Throttle position (TP) sensor.

Idle air control (IAC) solenoid.

Intake air temperature (IAT) sensor. Refer to
Intake Air Temperature Sensor.
035RW023
5. Disconnect the vacuum hose below the air horn.
6. Remove the intake air duct clamp.
7. Disconnect the intake air duct.
8. Disconnect the coolant lines from the throttle body.
9. Remove the bolts from the common chamber.
10. Remove the throttle body from the common chamber.
11. Remove the gasket from the upper intake manifold.
035RW024
12. Remove the IAC. Refer to Idle Air Control (IAC)
Solenoid
.
13. Remove the TP sensor. Refer to
Throttle Position
(TP) Sensor
.
Inspection Procedure
NOTE: Do not use solvent of any type when you clean the
gasket surfaces on the intake manifold and the throttle
body assembly. The gasket surfaces and the throttle
body assembly may be damaged as a result.

If the throttle body gasket needs to be replaced,
remove any gasket material that may be stuck to the
mating surfaces of the manifold.

Do not leave any scratches in the aluminum casting.
Installation Procedure
1. Install the TP sensor. Refer to Throttle Position (TP)
Sensor
.
2. Install the IAC. Refer to
Idle Air Control (IAC)
Solenoid
.
3. Install the gasket on the common chamber.
4. Install the throttle body on the common chamber.