check engine ISUZU TROOPER 1998 Service Repair Manual

6E±301 ENGINE DRIVEABILITY AND EMISSIONS
2. Remove the PSP switch from the power steering line.

Plug the line to prevent excessive loss of fluid and
possible contamination of the power steering
system.
TS23760
Installation Procedure
1. Install the PSP switch in the power steering line.
TS23760
2. Connect the PSP switch pigtail to the wiring harness.
3. Check the power steering fluid level. Refer to
Power
Steering
.
4. Start the engine. Watch the PSP switch for signs of
fluid leakage.
Throttle Position (TP) Sensor
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the TPS electrical connector.3. Remove the bolts and the TP sensor from the throttle
body.
TS23747
NOTE: Do not clean the TP sensor by soaking it in
solvent. The sensor will be damaged as a result.
Function Check
Use a Tech 2 to check the TP sensor output voltage at
closed throttle.

The voltage should be under 0.85 volt.

If the reading is greater than 0.85 volt, check the
throttle shaft to see if it is binding. Check that the
throttle cable is properly adjusted, also. Refer to
Throttle Cable Adjustment.

If the throttle shaft is not binding and the throttle cable
is properly adjusted, install a new TP sensor.
Installation Procedure
1. Install the TP sensor on the throttle body with the
bolts.
TS23747

6E±303 ENGINE DRIVEABILITY AND EMISSIONS
4. Check the transfer case oil level. Add fluid if
necessary.
5. Connect the negative battery cable.
Air Cleaner/Air Filter
Removal Procedure
1. Loosen the clamp between the air cleaner lid and the
mass air flow sensor.
2. Release the four latches securing the lid to the air
cleaner housing.
3. Remove the air cleaner lid.
TS23973
4. Remove the air filter element.
TS23794
5. Remove the retaining bolts and the air cleaner
housing from the vehicle.
130RT002
Installation Procedure
1. Install the air cleaner housing in the vehicle with the
retaining bolts.
130RT002

6E±306
ENGINE DRIVEABILITY AND EMISSIONS
4. Remove the accelerator control cable (on the
accelerator pedal end).
TS23982
5. Remove the grommet.
6. Remove the accelerator control cable.
TS23983
Inspection Procedure
Check the following items, and replace the control cable if
any abnormality is found:

The control cable should move smoothly.

The control cable should not be bent or kinked.

The control cable should be free of damage and
corrosion.
Installation Procedure
1. Install the accelerator control cable.
TS23983
2. Install the grommet.
3. Install the accelerator control cable (on the
accelerator pedal end).
TS23982

6E±310
ENGINE DRIVEABILITY AND EMISSIONS
Pedal Stroke Adjustment Procedure
1. Loosen the jam nut and rotate the kick-down switch
counterclockwise.
TS24039
2. Fully depress the pedal and hold it by hand. Rotate
the switch clockwise until the switch clicks.
3. Rotate the switch 1/2 turn further and lock it in this
position by tightening the jam nut.
TS24040
4. Step on the accelerator pedal and make sure there is
a clicking sound at the full-stroke position.
Fuel Filter Cap
General Description
The fuel filler cap includes a vacuum valve and a pressure
valve.If high vacuum or high pressure occurs in the fuel tank,
each valve works to adjust the pressure in order to
prevent damage to the tank at the EGR valve.
TS23767
Inspection Procedure
NOTE: Replace the fuel filler cap with the same type of
filler cap that was originally installed on the vehicle.

Check the seal ring in the filler cap for any abnormality
and for seal condition.

Replace the filler cap if any abnormality is found.
Fuel Filter
Removal Procedure
1. Disconnect the negative battery cable.
2. Remove the fuel filler cap.
041RW005

6E±314
ENGINE DRIVEABILITY AND EMISSIONS
3. Connect the wiring connector to the fuel gauge unit.
TS23771
4. Fill the fuel tank with fuel.

Tighten the fuel filler cap.

Check for leaks at the fuel gauge unit gasket.
5. Connect the negative battery cable.
Fuel Injectors
Removal Procedure
NOTE: If the fuel injectors are leaking, the engine oil may
be contaminated with fuel. Check the oil for signs of
contamination and change the oil and the filter if
necessary.
NOTE: Use care in removing the fuel injectors in order to
prevent damage to the fuel injector electrical connector
pins or the fuel injector nozzles. The fuel injector is an
electrical component and should not be immersed in any
type of cleaner as this may damage the fuel injector.
IMPORTANT:Fuel injectors are serviced as a complete
assembly only.
1. Disconnect the negative battery cable.
2. Remove the upper intake manifold. Refer to
Common Chamber in Engine Mechanical..
3. Remove the fuel rail. Refer to
Fuel Rail.
014RW164
4. Remove the injector retainer clip.
055RW009
5. Remove the fuel injector assembly.
6. Remove the O-ring from the fuel injector.
7. Remove the O-ring backup from the fuel injector .
Inspection Procedure
1. Inspect the O-rings for cracks or leaks.
2. Replace worn or damaged O-rings.
3. Lubricate the new O-rings with engine oil before
installation.

6E±325 ENGINE DRIVEABILITY AND EMISSIONS
Spark Plug Gap Check

Check the gap of all spark plugs before installation.

Use a round wire feeler gauge to ensure an accurate
check.

Plugs installed with the wrong gap can cause poor
engine performance and excessive emissions.
Installation Procedure
NOTE: The plug must thread smoothly into the cylinder
head and be fully seated. Use a thread chaser if
necessary to clean the threads in the cylinder head.
Cross-threading or failure to fully seat the spark plug can
cause plug overheating, exhaust blow-by gas, or thread
damage. Do not overtighten the spark plugs. Over
tightening can cause aluminum threads to strip.
1. Install the spark plug in the engine. Use the
appropriate spark plug socket.
Tighten

Tighten the spark plug to 18 N´m (13 lb ft.).
2. Install the ignition coil and spark plug boot over the
spark plug.
014RW108
3. Secure the ignition coil to the rocker cover with two
screws.
014RW091
4. Connect the electrical connector at the ignition coil.
5. Connect the negative battery cable.
Catalytic Converter
Removal and Installation Procedure
Refer to Engine Exhaust in Engine.
Air Conditioning Relay
Removal Procedure
1. Remove the fuse and relay box cover from under the
hood.
2. Consult the diagram on the cover to determine which
is the correct relay.
3. Insert a small screwdriver into the catch slot on the
forward side of the fuel pump relay.

The screwdriver blade will release the catch inside.
T321092

6E±330
ENGINE DRIVEABILITY AND EMISSIONS
Wiring and Connectors
Wiring Harness Service
The control module harness electrically connects the
control module to the various solenoids, switches and
sensors in the vehicle engine compartment and
passenger compartment.
Replace wire harnesses with the proper part number
replacement.
Because of the low amperage and voltage levels utilized
in powertrain control systems, it is essential that all wiring
in environmentally exposed areas be repaired with crimp
and seal splice sleeves.
The following wire harness repair information is intended
as a general guideline only. Refer to
Chassis Electrical for
all wire harness repair procedures.
Connectors and Terminals
Use care when probing a connector and when replacing
terminals. It is possible to short between opposite
terminals. Damage to components could result. Always
use jumper wires between connectors for circuit
checking. NEVER probe through Weather-Pack seals.
Use an appropriate connector test adapter kit which
contains an assortment of flexible connectors used to
probe terminals during diagnosis. Use an appropriate
fuse remover and test tool for removing a fuse and to
adapt the fuse holder to a meter for diagnosis.
Open circuits are often difficult to locate by sight because
oxidation or terminal misalignment are hidden by the
connectors. Merely wiggling a connector on a sensor, or
in the wiring harness, may temporarily correct the open
circuit. Intermittent problems may also be caused by
oxidized or loose connections.
Be certain of the type of connector/terminal before
making any connector or terminal repair. Weather-Pack
and Com-Pack III terminals look similar, but are serviced
differently.
PCM Connectors and Terminals
Removal Procedure
1. Remove the connector terminal retainer.
2. Push the wire connected to the affected terminal
through the connector face so that the terminal is
exposed.
3. Service the terminal as necessary.
Installation Procedure
1. Bend the tab on the connector to allow the terminal to
be pulled into position within the connector.
2. Pull carefully on the wire to install the connector
terminal retainer.
Wire Harness Repair: Twisted
Shielded Cable
Removal Procedure
1. Remove the outer jacket.
2. Unwrap the aluminum/mylar tape. Do not remove the
mylar.
047
3. Untwist the conductors.
4. Strip the insulation as necessary.
048

6E±344
ENGINE DRIVEABILITY AND EMISSIONS
0006
Run Mode
The run mode has the following two conditions:

Open loop

Closed loop
When the engine is first started the system is in ªopen
loopº operation. In ªopen loop,º the PCM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAF sensors.
The system remains in ªopen loopº until the following
conditions are met:

The HO2S has a varying voltage output showing that
it is hot enough to operate properly (this depends on
temperature).

The ECT has reached a specified temperature.

A specific amount of time has elapsed since starting
the engine.

Engine speed has been greater than a specified RPM
since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters ªclosed loopº operation. In
ªclosed loop,º the PCM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.
Starting Mode
When the ignition is first turned ªON,º the PCM energizes
the fuel pump relay for two seconds to allow the fuel pump
to build up pressure. The PCM then checks the engine
coolant temperature (ECT) sensor and the throttle
position (TP) sensor to determine the proper air/fuel ratio
for starting.
The PCM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors are
energized by pulsing the injectors for very short times.
Throttle Body Unit
The throttle body has a throttle plate to control the amount
of air delivered to the engine. The TP sensor and IAC
valve are also mounted on the throttle body. Vacuum
ports located behind the throttle plate provide the vacuum
signals needed by various components.
Engine coolant is directed through a coolant cavity in the
throttle body to warm the throttle valve and to prevent
icing.
0019
General Description (Electronic
Ignition System)
Camshaft Position (CMP) Sensor
As the camshaft sprocket turns, a magnet in the sprocket
activates the Hall-effect switch in the CMP sensor. When
the Hall-effect switch is activated, it grounds the signal
line to the PCM, pulling the camshaft position sensor
signal circuit's applied voltage low. This is a CMP signal.
The CMP signals is created as piston #1 is approximately
25
after top dead counter on the power stroke. If the
correct CMP signal is not received by the PCM, DTC
P0341 will be set.

6E±348
ENGINE DRIVEABILITY AND EMISSIONS
oil to enter the cylinder, particularly if the deposits are
heavier on the side of the spark plug facing the intake
valve.
TS23995
Excessive gap means that the air space between the
center and the side electrodes at the bottom of the spark
plug is too wide for consistent firing. This may be due to
improper gap adjustment or to excessive wear of the
electrode during use. A check of the gap size and
comparison to the gap specified for the vehicle in
Maintenance and Lubrication will tell if the gap is too wide.
A spark plug gap that is too small may cause an unstable
idle condition. Excessive gap wear can be an indication
of continuous operation at high speeds or with engine
loads, causing the spark to run too hot. Another possible
cause is an excessively lean fuel mixture.
TS23992
Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear. The plug
and the cylinder head seats must be in good contact for
proper heat transfer and spark plug cooling. Dirty or
damaged threads in the head or on the spark plug cankeep it from seating even though the proper torque is
applied. Once spark plugs are properly seated, tighten
them to the torque shown in the Specifications Table. Low
torque may result in poor contact of the seats due to a
loose spark plug. Overtightening may cause the spark
plug shell to be stretched and will result in poor contact
between the seats. In extreme cases, exhaust blow-by
and damage beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re-gapping, or heat shock to the insulator material. Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.
TS23994
A broken or cracked lower insulator tip (around the center
electrode) may result from damage during re-gapping or
from ªheat shockº (spark plug suddenly operating too
hot).
TS23993

6F±3 ENGINE EXHAUST
For Isuzu General Motors (IGM)
150RW058
When inspecting or replacing exhaust system
components, make sure there is adequate clearance
from all points on the underbody to prevent overheating
the floor pan and possible damage to the passenger
compartment insulation and trim materials.
Check complete exhaust system and nearby body areas
and rear compartment lid for broken, damaged, missing
or mispositioned parts, open seams, holes, loose
connections or other deterioration which could permit
exhaust fumes to seep into the rear compartment or
passenger compartment. Dust or water in the rear
compartment may be an indication of a problem in one of
these areas. Any faulty areas should be corrected
immediately.
Hangers
Various types of hangers are used to support exhaust
system(s). These include conventional rubber straps,
rubber rings, and rubber blocks.
The installation of exhaust system supports is very
important, as improperly installed supports can cause
annoying vibrations which can be difficult to diagnose.
Three Way Catalytic Converter
The three way catalytic converter is an emission control
device added to the exhaust system to reduce pollutants
from the exhaust gas stream.
CAUTION: The catalytic converter requires the use
of unleaded fuel only.
Periodic maintenance of the exhaust system is not
required. If the vehicle is raised for other service, it is
advisable to check the condition of the complete exhaust
system.
A dual bed monolith catalytic converter is used in
combination with three way catalytic converter.
Catalytic Types:
Three way (Reduction/Oxidation) catalyst
The catalyst coating on the three way (reduction)
converter contains platinum and rhodium which lowers
the levels of nitrous oxide (NOx) as well as hydrocarbons
(HC) and carbon monoxide (Co).
Gasket
The gasket must be replaced whenever a new exhaust
pipe, muffler or catalytic converter is installed.