removing engine ISUZU TROOPER 1998 Service Owner's Guide

6E±339 ENGINE DRIVEABILITY AND EMISSIONS
0005
PCM Components
The PCM is designed to maintain exhaust emission levels
to government mandated standards while providing
excellent driveability and fuel efficiency. The PCM
monitors numerous engine and vehicle functions via
electronic sensors such as the throttle position (TP)
sensor, heated oxygen sensor (HO2S), and vehicle
speed sensor (VSS). The PCM also controls certain
engine operations through the following:

Fuel injector control

Ignition control module

Knock sensor

Automatic transmission shift functions

Cruise control

A/C clutch control
PCM Voltage Description
The PCM supplies a buffered voltage to various switches
and sensors. It can do this because resistance in the
PCM is so high in value that a test light may not illuminate
when connected to the circuit. An ordinary shop
voltmeter may not give an accurate reading because the
voltmeter input impedance is too low. Use a 10-megohm
input impedance digital voltmeter (such as J 39200) to
assure accurate voltage readings.
The input/output devices in the PCM include
analog-to-digital converters, signal buffers, counters,
and special drivers. The PCM controls most components
with electronic switches which complete a ground circuit
when turned ªON.º These switches are arranged in
groups of 4 and 7, called either a surface-mounted quad
driver module (QDM), which can independently control up
to 4 output terminals, or QDMs which can independently
control up to 7 outputs. Not all outputs are always used.
PCM Input/Outputs
Inputs ± Operating Conditions Read

Air Conditioning ªONº or ªOFFº
Engine Coolant Temperature

Crankshaft Position

Exhaust Oxygen Content

Electronic Ignition

Manifold Absolute Pressure

Battery Voltage

Throttle Position

Vehicle Speed

Fuel Pump Voltage

Power Steering Pressure

Intake Air Temperature

Mass Air Flow

Engine Knock

Camshaft Position
Outputs ± Systems Controlled

Exhaust Gas Recirculation (EGR)

Ignition Control

Fuel Control

Idle Air Control

Electric Fuel Pump

Air Conditioning

Diagnostics
± Malfunction Indicator Lamp (Service Engine Soon
lamp)
± Data Link Connector (DLC)
± Data Output

Transmission Control Module

Alternator Gain Control
PCM Service Precautions
The PCM is designed to withstand normal current draws
associated with vehicle operation. Avoid overloading any
circuit. When testing for opens and shorts, do not ground
or apply voltage to any of the PCM's circuits unless
instructed to do so. These circuits should only be tested
Tech-2. The PCM should remain connected to the PCM
or to a recommended breakout box.
Reprogramming The PCM
The Trooper allow reprogramming of the PCM without
removing it from the vehicle . This provides a flexible and
cost-effective method of making changes in software
calibrations.
The service programming system (SPS) will not allow
incorrect software programming or incorrect calibration
changes.
Refer to the UBS 98model year Immobilizer Workshop
Manual.
Throttle Position (TP) Sensor
The throttle position (TP) sensor is a potentiometer
connected to the throttle shaft on the throttle body. The
PCM monitors the voltage on the signal line and
calculates throttle position. As the throttle valve angle is
changed (accelerator pedal moved), the TP sensor signal
also changes. At a closed throttle position, the output of

6E±341 ENGINE DRIVEABILITY AND EMISSIONS
this is done, if the problem still exists, it may be diagnosed
in the normal manner.
Electrostatic Discharge Damage
Electronic components used in the PCM are often
designed to carry very low voltage. Electronic
components are susceptible to damage caused by
electrostatic discharge. Less than 100 volts of static
electricity can cause damage to some electronic
components. By comparison, it takes as much as 4000
volts for a person to feel even the zap of a static
discharge.
TS23793
There are several ways for a person to become statically
charged. The most common methods of charging are by
friction and induction.

An example of charging by friction is a person sliding
across a vehicle seat.

Charge by induction occurs when a person with well
insulated shoes stands near a highly charged object
and momentary touches ground. Charges of the
same polarity are drained off leaving the person
highly charged with the opposite polarity. Static
charges can cause damage, therefore it is important
to use care when handling and testing electronic
components.
NOTE: To p r e ve n t p ossible electrostatic discharge
damage, follow these guidelines:

Do not touch the PCM connector pins or soldered
components on the PCM circuit board.

Do not touch the knock sensor module component
leads.

Do not open the replacement part package until the
part is ready to be installed.

Before removing the part from the package, ground
the package to a known good ground on the vehicle.

If the part has been handled while sliding across the
seat, while sitting down from a standing position, or
while walking a distance, touch a known good ground
before installing the part.
Upshift Lamp
Refer to Manual Transmission.
General Description (Air Induction)
Air Induction System
The air induction system filters contaminants from the
outside air, and directs the progress of the air as it is
drawn into the engine. A remote-mounted air cleaner
prevents dirt and debris in the air from entering the
engine. The air duct assembly routes filtered air to the
throttle body. Air enters the engine by to following steps:
1. Through the throttle body.
2. Into the common chamber.
3. Through the cylinder head intake ports.
4. Into the cylinders.
055RV010
General Description (Fuel Metering)
Acceleration Mode
The PCM provides extra fuel when it detects a rapid
increase in the throttle position and the air flow.
Accelerator Controls
The accelerator control system is a cable-type system
with specific linkage adjustments.
Refer to
Cable Adjustment.
Battery Voltage Correction Mode
When battery voltage is low, the PCM will compensate for
the weak spark by increasing the following:

The amount of fuel delivered.

The idle RPM.

Ignition dwell time.
CMP Signal
The PCM uses this signal to determine the position of the
number 1 piston during its power stroke, allowing the

6G±12
ENGINE LUBRICATION
Oil Pump Oil Seal
Removal
1. Disconnect battery ground cable.
2. Drain engine oil.
3. Remove crankshaft pulley.

Refer to removal procedure for Crankshaft Pulley in
this manual.
4. Remove timing belt.

Refer to removal procedure for Timing Belt in this
manual.
5. Remove timing pulley from crankshaft.
6. Remove oil pump oil seal using a sealer puller.
NOTE: Take care not to damage sealing surfaces of oil
pump and crankshaft when removing oil seal.
Installation
1. Install oil pump oil seal, apply engine oil to oil seal lip,
then install oil seal using 5±8840±2287±0 installer.
015RS001
2. Install timing pulley to crankshaft.
3. Install timing belt.

Refer to installation procedure for Timing Belt in this
manual.
4. Install crankshaft pulley.

Refer to installation procedure for Crankshaft
Pulley in this manual.
5. Refill engine oil until full level.

6A Ð 2 ENGINE MECHANICAL
CYLINDER HEAD
NOTE:
·During disassembly, be sure that the valve train
components are kept together and identified so that
they can be re-installed in their original locations.
·Before removing the cylinder head from the engine
and before disassembling the valve mechanism, make
a compression test and note the results.
DISASSEMBLY
1. Thermostat Housing Assembly
2. Injection Nozzle Holder
3. Glow Plug and Glow Plug Connector
4. Rocker Arm Shaft and Rocker Arm
5. Push Rod
6. Cylinder Head
·Refer to Section 6A2 ÒCylinder HeadÓ
CLEAN
·Cylinder head bolts
·Cylinder head
Carefully remove all varnish, soot and carbon to the
bare metal. Do not use a motorized wire brush on any
gasket sealing surface.

ENGINE MECHANICAL 6A Ð 5
2. Place an appropriate metal plate  thick over the hot
plug upper surface à .
3. Use a press Ä to exert a pressure of 44000-
54000N(4500 Ð 5500 kg) (9923 Ð 12128 lbs.) on the
metal plate covering the hot plug upper surface. This
will drive the hot plug into position.
4. Lightly tap the hot plug heads to make sure that they
are firmly seated.
5. Repeat the procedure Steps 1-4 for the remaining hot
plugs.
CAUTION:
Do not apply pressure greater than that specified. Dam-
age to the cylinder head will result.
6. Use a surface grinder to grind off any hot plug sur-
face protuberances.
The hot plug surfaces must be perfectly flush with the
cylinder head.
7. After grinding, make sure that the hot plug surfaces
are completely free of protuberances.
The hot plug surfaces must also be free of depres-
sions.
Once again, lightly tap the hot plug heads to make sure
that they are firmly seated.
Heat shield removal
After removing the hot plugs, use a hammer À and a
brass bar Á to lightly tap the lower side of the heat
shiled  and drive it free.
Heat shield installation
Install the heat shield washer and the heat shield to the
cylinder head from the nozzle holder installation hole
side. Lightly tap the flange into place with a brass bar.
The heat shield flange side must be facing up.
NOTE:
Always install a new heat shield. Never reuse the old
heat shield.

6A Ð 8 ENGINE MECHANICAL
At installed
height 38.9mm
(1.5in)StandardN(Kg/lb)
Limit
294.0 (30/66.1)257.9 (26.3/57.9)
Valve spring
CAUTION:
Visually inspect the valve springs and replace them if
damage or abnormal wear is evident.
1. Free height
·Measure the free height of the springs. The springs
must be replaced if the height is below the specified
limit.
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered
during inspection.
2. Squareness
·Measure the valve spring squareness with a steel
square.
·Replace the valve springs if the measured value
exceeds the specified limit.
3. Spring tension
·Use a spring tester to compress the springs to the
installed height. Measure the compressed spring
tension.
Replace the springs if the measured tension is
below the specified limit.
Valve Guide
CAUTION:
Taking care not to damage the valve seat contact surface,
when removing carbon adhering to the valve head.
Carefully inspect the valve stem for scratching or
abnormal wear. If these conditions are present, the valve
and the valve guide must be replaced as a set.
Limitmm(in)
1.7 (0.0669)
Standard Limit
48.0 (1.8898) 47.100 (1.8543)mm(in)

ENGINE MECHANICAL 6A Ð 15
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered
during inspection.
8. Camshaft
9. Tappet
1. Measure the Camshaft Thrust Clearance.
¥ Use a dial indicator to measure the camshaft end
play.
This must be done before removing the camshaft
gear.
If the camshaft end play exceeds the specified
limit, the thrust plate must be replaced.
2. Camshaft Journal Diameter
¥ Use a micrometer to measure each camshaft
journal diameter in two directions (1 and 2). If the
measured value is less than the specified limit,
the camshaft must be replaced.
3. Cam Height
¥ Measure the cam height H with a micrometer. If
the measured value is less than the specified
limit, the camshaft must be replaced.
Standard Limit
mm(in)
49.945-49.975 (1.9663-1.9675) 49.60 (1.9528) Journal Diameter
Standard Limit
mm(in)
42.02 (1.6543) 41.65 (1.6398) Cam Height
Standard Limit
mm(in)
0.08 (0.0031) 0.2 (0.0079) Camshaft End Play

6A Ð 34 ENGINE MECHANICAL
PISTON AND CONNECTING ROD
DISASSEMBLY
1. Cylinder Head Assembly
·Refer to ÒCylinder headÓ in Section 6A2.
2. Crankcase Assembly
·Refer to ÒCrankcaseÓ in Section 6A2
3. Oil Pump Assembly
4. Connecting Rod Bearing Cap
5. Piston and Connecting Rod
·Remove carbon deposits from the upper portion
of the cylinder wall with a scraper before
removing the piston and connecting rod

6A2 Ð 2 4JG2-NA/4JG2-TURBO ENGINE
RECARD Comet V Type swirl combustion chamber which
provides superior driving performance, fuel economy and
silent combustion over a wide range of driving
conditions, is applied.
The cylinder head gasket is of laminated steel sheets.
Three grades of the gasket according to the measured
piston head projection from the cylinder block are
provided to give the engine a minimum compression
ration fluctuation.
The cylinder head fixing blots, flywheel bolts and con-
necting rod fixing bolts are tightened by the angular
Tightening Method.
The chrome plated steel dry type (Chromard) cylinder
liners provide the highest durability.
Auto-thermatic pistons having steel struts with 0.7 mm
offset from the piston pin center line, ate applied to
reduce thermal expansion and resulting engine noise
when the engine is cold.
The crankshaft bearings and connecting rod bearings are
of aluminum having a high bearing surface.
These bearing are especially sensitive to foreign material
such as metal scraps. So, it is very important that the oil
ports and other related surfaces are kept clean and free of
foreign material.
Crank shaft bearing selection for optimum bearing and
journal clearance is applied to reduce vibration and noise.
As tufftriding (Nitrizing treatment) is applied to increase
crankshaft strength, crankpins and journals should not be
reground.
An oiling jet device for piston cooling is provided in the
lubricating oil circuit from cylinder block oil gallery via a
check valve.
Take care not to damage any oiling jet when removing
and installing piston and connecting assembly.
The DFI (Double Formation Injection) Pintaux Type
injection nozzle having a sub-injection hole is applied.
This nozzle contributes to substantially minimize the
diesel knocking sound noticeable in the cold engine idling
operation.
Install the injection nozzle, directing the sub-injection hole
to the specified direction.
QOS III preheating system which features a quick-on glow
plug with thermometer control of the glowing time and
the afterglow time function, is applied.

4JG2-NA/4JG2-TURBO ENGINE 6A2 Ð 15
TIMING GEAR
REMOVAL
Preparation:
·Disconnect battery ground cable.
·Drain coolant.
1. P/S Pump Drive Belt
·Loosen P/S pump mounting bolt and adjust bolt,
and remove the drive belt.
2. AC Generator Drive Belt
·Loosen AC Generator mounting bolt (under side)
and adjust plate lock bolt, and remove the drive
belt.
3. Cooling Fan Assembly
·Remove clamp nut, and remove cooling fan asm,
distant pipe, and fan pulley.
4. Crankshaft Damper Pulley
5. Upper Noise Shield Cover
6. Lower Noise Shield Cover
7. Noise Cover Spacer.
8. Timing Gear Case Cover
9. Oil Pipe
10. Idler Gear ÒBÓ and Shaft
1) Measure the camshaft timing gear backlash and the
crenkshaft timing gear backlash before removing the
idler gear.