1998 ISUZU TROOPER Service Repair Manual

MPG alternator wiper size fuel fill door release climate settings ABS

Page 1465 of 3573

ISUZU TROOPER 1998 Service Repair Manual 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 th

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

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ISUZU TROOPER 1998 Service Repair Manual 6E±349 ENGINE DRIVEABILITY AND EMISSIONS
Damage during re-gapping can happen if the gapping
tool is pushed against the center electrode or the
insulator around it, causing the insulator to crack.
Wh

6E±349 ENGINE DRIVEABILITY AND EMISSIONS
Damage during re-gapping can happen if the gapping
tool is pushed against the center electrode or the
insulator around it, causing the insulator to crack.
When re-gapping a spark plug, make the adjustment
by bending only the ground side terminal, keeping the
tool clear of other parts.
ºHeat shockº breakage in the lower insulator tip
generally occurs during several engine operating
conditions (high speeds or heavy loading) and may be
caused by over-advanced timing or low grade fuels.
Heat shock refers to a rapid increase in the tip
temperature that causes the insulator material to
crack.
Spark plugs with less than the recommended amount of
service can sometimes be cleaned and re-gapped , then
returned to service. However, if there is any doubt about
the serviceability of a spark plug, replace it. Spark plugs
with cracked or broken insulators should always be
replaced.
A/C Clutch Diagnosis
A/C Clutch Circuit Operation
A 12-volt signal is supplied to the A/C request input of the
PCM when the A/C is selected through the A/C control
switch.
The A/C compressor clutch relay is controlled through the
PCM. This allows the PCM to modify the idle air control
position prior to the A/C clutch engagement for better idle
quality. If the engine operating conditions are within their
specified calibrated acceptable ranges, the PCM will
enable the A/C compressor relay. This is done by
providing a ground path for the A/C relay coil within the
PCM. When the A/C compressor relay is enabled,
battery voltage is supplied to the compressor clutch coil.
The PCM will enable the A/C compressor clutch
whenever the engine is running and the A/C has been
requested. The PCM will not enable the A/C compressor
clutch if any of the following conditions are met:
The throttle is greater than 90%.
The engine speed is greater than 6315 RPM.
The ECT is greater than 119C (246F).
The IAT is less than 5C (41F).
The throttle is more than 80% open.
A/C Clutch Circuit Purpose
The A/C compressor operation is controlled by the
powertrain control module (PCM) for the following
reasons:
It improvises idle quality during compressor clutch
engagement.
It improvises wide open throttle (WOT) performance.
It provides A/C compressor protection from operation
with incorrect refrigerant pressures.
The A/C electrical system consists of the following
components:
The A/C control head.
The A/C refrigerant pressure switches.
The A/C compressor clutch.
The A/C compressor clutch relay.The PCM.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning on the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for A/C electrical system.
General Description (Exhaust Gas
Recirculation (EGR) System)
EGR Purpose
The exhaust gas recirculation (EGR) system is use to
reduce emission levels of oxides of nitrogen (NOx). NOx
emission levels are caused by a high combustion
temperature. The EGR system lowers the NOx emission
levels by decreasing the combustion temperature.
057RW002
Linear EGR Valve
The main element of the system is the linear EGR valve.
The EGR valve feeds small amounts of exhaust gas back
into the combustion chamber. The fuel/air mixture will be
diluted and combustion temperatures reduced.
Linear EGR Control
The PCM monitors the EGR actual positron and adjusts
the pintle position accordingly. The uses information from
the following sensors to control the pintle position:
Engine coolant temperature (ECT) sensor.
Throttle position (TP) sensor.
Mass air flow (MAF) sensor.
Linear EGR Valve Operation and Results
of Incorrect Operation
The linear EGR valve is designed to accurately supply
EGR to the engine independent of intake manifold
vacuum. The valve controls EGR flow from the exhaust

Page 1467 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±350
ENGINE DRIVEABILITY AND EMISSIONS
to the intake manifold through an orifice with a PCM
controlled pintle. During operation, the PCM controls
pintle position by monitoring the pintle position

6E±350
ENGINE DRIVEABILITY AND EMISSIONS
to the intake manifold through an orifice with a PCM
controlled pintle. During operation, the PCM controls
pintle position by monitoring the pintle position feedback
signal. The feedback signal can be monitored with Tech 2
as ªActual EGR Pos.º ªActual EGR Pos.º should always
be near the commanded EGR position (ºDesired EGR
Pos.º). If a problem with the EGR system will not allow the
PCM to control the pintle position properly, DTC P1406
will set. The PCM also tests for EGR flow. If incorrect flow
is detected, DTC P0401 will set. If DTCs P0401 and/or
P1406 are set, refer to the DTC charts.
The linear EGR valve is usually activated under the
following conditions:
Warm engine operation.
Above-idle speed.
Too much EGR flow at idle, cruise or cold operation may
cause any of the following conditions to occur:
Engine stalls after a cold start.
Engine stalls at idle after deceleration.
Vehicle surges during cruise.
Rough idle.
Too little or no EGR flow may allow combustion
temperatures to get too high. This could cause:
Spark knock (detonation).
Engine overheating.
Emission test failure.
DTC P0401 (EGR flow test).
Poor fuel economy.
0017
EGR Pintle Position Sensor
The PCM monitors the EGR valve pintle position input to
endure that the valve responds properly to commands
from the PCM and to detect a fault if the pintle position
sensor and control circuits are open or shorted. If the
PCM detects a pintle position signal voltage outside the
normal range of the pintle position sensor, or a signal
voltage that is not within a tolerance considered
acceptable for proper EGR system operation, the PCM
will set DTC P1406.
General Description (Positive
Crankcase Ventilation (PCV) System)
Crankcase Ventilation System Purpose
The crankcase ventilation system is use to consume
crankcase vapors in the combustion process instead of
venting them to the atmosphere. Fresh air from the
throttle body is supplied to the crankcase and mixed with
blow-by gases. This mixture is then passed through the
positive crankcase ventilation (PCV) valve into the
common chamber.
Crankcase Ventilation System Operation
The primary control is through the positive crankcase
ventilation (PCV) valve. The PCV valve meters the flow at
a rate that depends on the intake vacuum. The PCV valve
restricts the flow when the inlet vacuum is highest. In
addition, the PCV valve can seal the common chamber
off in case of sudden high pressure in the crankcase.
028RV002
While the engine is running, exhaust fuses and small
amounts of the fuel/air mixture escape past the piston

Page 1468 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±351 ENGINE DRIVEABILITY AND EMISSIONS
rings and enter the crankcase. These gases are mixed
with clean air entering through a tube from the air intake
duct.
028RW002
During normal, part-throttle o

Page 1469 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±352
ENGINE DRIVEABILITY AND EMISSIONS
Special Tools
901RW180
Legend
(1) PCMCIA Card
(2) RS232 Loop Back Connector(3) SAE 16/19 Adapter
(4) DLC Cable
(5) TECH±2

Page 1470 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±353 ENGINE DRIVEABILITY AND EMISSIONS
ILLUSTRATIONTOOL NO.
TOOL NAME
5-8840-0285-0
(J 39200)
High Impedance
Multimeter (Digital
Voltmeter ± DVM)
(1) PCMCIA Card
(2) RS232 Loop Back
Connector
(3

Page 1471 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±354
ENGINE DRIVEABILITY AND EMISSIONS
ILLUSTRATIONTOOL NO.
TOOL NAME
5-8840-2607-0
(J 41413)
EVAP Pressure/Purge
Diagnostic Station
5-8840-2608-0
(J 41416)
Ultrasonic Leak Detector
1. 5-8840-2607-

Page 1472 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6F±1 ENGINE EXHAUST
ENGINE
ENGINE EXHAUST
CONTENTS
Service Precaution 6F±1. . . . . . . . . . . . . . . . . . . . . .
General Description 6F±2. . . . . . . . . . . . . . . . . . . . .
Front Exhau

6F±1 ENGINE EXHAUST
ENGINE
ENGINE EXHAUST
CONTENTS
Service Precaution 6F±1. . . . . . . . . . . . . . . . . . . . . .
General Description 6F±2. . . . . . . . . . . . . . . . . . . . .
Front Exhaust Pipe 6F±4. . . . . . . . . . . . . . . . . . . . . .
Front Exhaust Pipe and Associated Parts 6F±4.
Removal 6F±4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6F±4. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Three Way Catalytic Converter 6F±5. . . . . . . . . . . .
Removal 6F±5. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6F±5. . . . . . . . . . . . . . . . . . . . . . . . . . . . Exhaust Silencer 6F±6. . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Silencer and Associated Parts 6F±6. . .
Removal 6F±6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6F±6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Exhaust pipe 6F±7. . . . . . . . . . . . . . . . . . . . . . .
Rear Exhaust pipe and Associated Parts 6F±7.
Removal 6F±7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6F±7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 6F±8. . . . . . . . . . . . .
Service Precaution
WARNING: I F S O E Q U IPPED WITH A
SUPPLEMENTAL RESTRAINT SYSTEM (SRS),
REFER TO THE SRS COMPONENT AND WIRING
LOCATION VIEW IN ORDER TO DETERMINE
WHETHER YOU ARE PERFORMING SERVICE ON OR
NEAR THE SRS COMPONENTS OR THE SRS
WIRING. WHEN YOU ARE PERFORMING SERVICE
ON OR NEAR THE SRS COMPONENTS OR THE SRS
WIRING, REFER TO THE SRS SERVICE
INFORMATION. FAILURE TO FOLLOW WARNINGS
COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.

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