1998 ISUZU TROOPER change time

6E±257 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1618 Serial Peripheral Interface (SPI) PCM
Interprocessor Communication Error
Circuit Description
The serial peripheral interface (SPI) communication is
used internally by the PCM to send messages between
the engine processor and the automatic transmission
processor. Included in each message sent between the
two-processors is a checksum of the message. Both the
engine processor and automatic transmission processor
will compare this check sum value with the calculated
value. If the checksums don't match, the processor will
view the new data as being corrupted and ignore the
values. The processor will then use the previous
message. The receiving processor will then send a
message to the sending processor informing it that it's
last message was corrupted.
Conditions for Setting the DTC

Battery voltage is above 9.0 V for 2 seconds.

The PCM detects an internal program fault (check sum
of data communications error).
Check sum fault present for 3 out 6 seconds.

No TCM resets for 2 seconds.
Action Taken When the DTC Sets

The PCM will flash the ªCheck Transº lamp the first
time the fault is detected.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

The automatic transmission will operate in the ªsafety
modeº to protect the mechanical parts of the
transmission. Shift quality and/or gear changes may
not be normal.
Conditions for Clearing the MIL/DTC

DTC P1618 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
DTC P1618 ± Serial Peripheral Interface (SPI) PCM Interprocessor
Communication Error

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Is the EEPROM calibration the latest version
available?
ÐGo to Step 4Go to Step 3
3Reprogram the PCM with the latest available
calibrations.
Does DTC 1618 re-appear when the
OBD System
Check
is repeated?ÐGo to Step 4
Repair
completed
4Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±337 ENGINE DRIVEABILITY AND EMISSIONS
0018
Knock Sensor
Insufficient gasoline octane levels may cause detonation
in some engines. Detonation is an uncontrolled explosion
(burn) in the combustion chamber. This uncontrolled
explosion results from a flame front opposite that of the
normal flame front produced by the spark plug. The
rattling sound normally associated with detonation is the
result of two or more opposing pressures (flame fronts)
colliding within the combustion chamber. Light
detonation is sometimes considered normal, but heavy
detonation could result in engine damage.
A knock sensor system is used to control detonation. This
system is designed to retard spark timing up to 20
degrees to reduce detonation in the engine. This allows
the engine to use maximum spark advance to improve
driveability and fuel economy.
The knock sensor system has two major components:

The knock sensor (KS) module.

The knock sensor.
The knock sensor, mounted in the engine block near the
cylinders, detects abnormal vibration in the engine. The
sensor produces an AC output signal of about 10
millivolts. The signal amplitude and frequency are
dependent on the amount of knock being experienced.
The signal voltage increases with the severity of the
knock. This signal voltage is input to the PCM. The PCM
then retards the ignition control (IC) spark timing based
on the KS signal being received.
The PCM determines whether knock is occurring by
comparing the signal level on the KS circuit with the
voltage level on the noise channel. The noise channel
allows the PCM to reject any false knock signal by
indicating the amount of normal engine mechanical noise
present. Normal engine noise varies depending on the
engine speed and load. If the voltage level on the KS
noise channel circuit is below the range considered
normal, DTC P0327 will set, indicating a fault in the KScircuit or the knock sensor. If the PCM determines that an
abnormal minimum or maximum noise level is being
experienced, DTC P0325 will set.
The PCM contains a knock sensor (KS) module. The KS
module contains the circuitry which allows the PCM to
utilize the KS signal and diagnose the KS sensor and the
KS circuitry. If the KS module is missing or faulty, a
continuous knock condition will be indicated, and the
PCM will set DTC P0325.
Although it is a plug-in device, the KS module is not
replaceable. If the KS module is faulty, the entire PCM
must be replaced.
0009
Linear Exhaust Gas Recirculation (EGR)
Control
The PCM monitors the exhaust gas recirculation (EGR)
actual position and adjusts the pintle position accordingly.
The PCM 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.
Mass Air Flow (MAF) Sensor
The mass air flow (MAF) sensor measures the difference
between the volume and the quantity of air that enters the
engine. ªVolumeº means the size of the space to be filled.
ªQuantityº means the number of air molecules that will fit
into the space. This information is important to the PCM
because heavier, denser air will hold more fuel than
lighter, thinner air. The PCM adjusts the air/fuel ratio as
needed depending on the MAF value. Tech 2 reads the
MAF value and displays it in terms of grams per second
(gm/s). At idle, Tech 2 should read between 4-7 gm/s on a
fully warmed up engine. Values should change quickly on
acceleration. Values should remain stable at any given

6E±342
ENGINE DRIVEABILITY AND EMISSIONS
PCM to calculate true sequential multiport fuel injection
(SFI). Loss of this signal will set a DTC P0341. If the CMP
signal is lost while the engine is running, the fuel injection
system will shift to a calculated sequential fuel injection
based on the last fuel injection pulse, and the engine will
continue to run. The engine can be restarted and will run
in the calculated sequential mode as long as the fault is
present, with a 1-in-6 chance of being correct.
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal
down all the way. The PCM then de-energizes the fuel
injectors. The PCM holds the fuel injectors de-energized
as long as the throttle remains above 80% and the engine
speed is below 800 RPM. If the throttle position becomes
less than 80%, the PCM again begins to pulse the
injectors ªONº and ªOFF,º allowing fuel into the cylinders.
Deceleration Mode
The PCM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air flow.
When deceleration is very fast, the PCM may cut off fuel
completely for short periods.
Engine Speed/Vehicle Speed/Fuel Disable
Mode
The PCM monitors engine speed. It turns off the fuel
injectors when the engine speed increase above 6400
RPM. The fuel injectors are turned back on when engine
speed decreases below 6150 RPM.
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the ignition
is ªOFF.º This prevents engine run-on. In addition, the
PCM suspends fuel delivery if no reference pulses are
detected (engine not running) to prevent engine flooding.
Fuel Injector
The sequential multiport fuel injection (SFI) fuel injector is
a solenoid-operated device controlled by the PCM. The
PCM energizes the solenoid, which opens a valve to allow
fuel delivery.
The fuel is injected under pressure in a conical spray
pattern at the opening of the intake valve. Excess fuel not
used by the injectors passes through the fuel pressure
regulator before being returned to the fuel tank.
A fuel injector which is stuck partly open will cause a loss
of fuel pressure after engine shut down, causing long
crank times.
0003
Fuel Metering System Components
The fuel metering system is made up of the following
parts:

The fuel injectors.

The throttle body.

The fuel rail.

The fuel pressure regulator.

The PCM.

The crankshaft position (CKP) sensor.

The camshaft position (CMP) sensor.

The idle air control (IAC) valve.

The fuel pump.

The fuel pump relay.
Basic System Operation
The fuel metering system starts with the fuel in the fuel
tank. An electric fuel pump, located in the fuel tank,
pumps fuel to the fuel rail through an in-line fuel filter. The
pump is designed to provide fuel at a pressure above the
pressure needed by the injectors. A fuel pressure
regulator in the fuel rail keeps fuel available to the fuel
injectors at a constant pressure. A return line delivers
unused fuel back to the fuel tank. Refer to
Section 6C for
further information on the fuel tank, line filter, and fuel
pipes.
Fuel Metering System Purpose
The basic function of the air/fuel metering system is to
control the air/fuel delivery to the engine. Fuel is delivered
to the engine by individual fuel injectors mounted in the
intake manifold near each intake valve.
The main control sensor is the heated oxygen sensor
(HO2S) located in the exhaust system. The HO2S tells
the PCM how much oxygen is in the exhaust gas. The
PCM changes the air/fuel ratio to the engine by controlling
the amount of time that fuel injector is ªON.º The best
mixture to minimize exhaust emissions is 14.7 parts of air
to 1 part of gasoline by weight, which allows the catalytic
converter to operate most efficiently. Because of the

6E±343 ENGINE DRIVEABILITY AND EMISSIONS
constant measuring and adjusting of the air/fuel ratio, the
fuel injection system is called a ªclosed loopº system.
The PCM monitors signals from several sensors in order
to determine the fuel needs of the engine. Fuel is
delivered under one of several conditions called ªmodes.º
All modes are controlled by the PCM.
Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated
relief valve mounted on the fuel rail with fuel pump
pressure on one side and manifold pressure on the other
side. The fuel pressure regulator maintains the fuel
pressure available to the injector at three times
barometric pressure adjusted for engine load. It may be
serviced separate.
If the pressure is too low, poor performance and a DTC
P0131, DTC P0151,DTC P0171 or DTC P1171 will be the
result. If the pressure is too high, excessive odor and/or a
DTC P0132, DTC P0152,DTC P0172 or DTC P0175 will
be the result. Refer to
Fuel System Diagnosis for
information on diagnosing fuel pressure conditions.
0011
Fuel Pump Electrical Circuit
When the key is first turned ªON,º the PCM energizes the
fuel pump relay for two seconds to build up the fuel
pressure quickly. If the engine is not started within two
seconds, the PCM shuts the fuel pump off and waits until
the engine is cranked. When the engine is cranked and
the 58 X crankshaft position signal has been detected by
the PCM, the PCM supplies 12 volts to the fuel pump relay
to energize the electric in-tank fuel pump.
An inoperative fuel pump will cause a ªno-startº condition.
A fuel pump which does not provide enough pressure will
result in poor performance.
Fuel Rail
The fuel rail is mounted to the top of the engine and
distributes fuel to the individual injectors. Fuel is
delivered to the fuel inlet tube of the fuel rail by the fuel
lines. The fuel goes through the fuel rail to the fuel
pressure regulator. The fuel pressure regulator maintainsa constant fuel pressure at the injectors. Remaining fuel
is then returned to the fuel tank.
055RW009
Idle Air Control (IAC) Valve
The purpose of the idle air control (IAC) valve is to control
engine idle speed, while preventing stalls due to changes
in engine load. The IAC valve, mounted in the throttle
body, controls bypass air around the throttle plate. By
moving the conical valve (pintle) in (to decrease air flow)
or out (to increase air flow), a controlled amount of air can
move around the throttle plate. If the RPM is too low, the
PCM will retract the IAC pintle, resulting in more air
moving past the throttle plate to increase the RPM. If the
RPM is too high, the PCM will extend the IAC pintle,
allowing less air to move past the throttle plate,
decreasing the RPM.
The IAC pintle valve moves in small steps called counts.
During idle, the proper position of the IAC pintle is
calculated by the PCM based on battery voltage, coolant
temperature, engine load, and engine RPM. If the RPM
drops below a specified value, and the throttle plate is
closed, the PCM senses a near-stall condition. The PCM
will then calculate a new IAC pintle valve position to
prevent stalls.
If the IAC valve is disconnected and reconnected with the
engine running, the idle RPM will be wrong. In this case,
the IAC must be reset. The IAC resets when the key is
cycled ªONº then ªOFF.º When servicing the IAC, it
should only be disconnected or connected with the
ignition ªOFF.º
The position of the IAC pintle valve affects engine start-up
and the idle characteristics of the vehicle. If the IAC pintle
is fully open, too much air will be allowed into the manifold.
This results in high idle speed, along with possible hard
starting and a lean air/fuel ratio. DTC P0507 or DTC
P1509 may set. If the IAC pintle is stuck closed, too little
air will be allowed in the manifold. This results in a low idle
speed, along with possible hard starting and a rich air/fuel
ratio. DTC P0506 or DTC P1508 may set. If the IAC
pintle is stuck part-way open, the idle may be high or low
and will not respond to changes in the engine load.

00 Ð 14 SERVICE INFORMATION
Condition Possible cause Correction
Engine overheating Low coolant level Replenish
Thermo unit faulty
Faulty thermostat
Faulty coolant unit
Clogged radiator
Faulty radiator cap
Low engine oil level or use of improper
engine oil
Damaged cylinder head gasket
Clogged exhaust system
Loose fan belt
Excessive fuel injected
Improper injection timing
Injection timing improper
Faulty thermostat
Faulty thermostatReplace
Replace
Repair or replace
Clean or replace
Replace
Replenish or change oil
Replenish
Replace
Clean exhaust system or replace
faulty parts
Adjust
Adjust
Adjust
Replace
Replace
Thermo unit faultyReplace Engine overcooling
Too long engine
warm-up time
Adjust
ENGINE COOLING TROUBLE

QOS III PREHEATING SYSTEM 6D6 Ð 1
PAGE
General Description ........................................................................................................ 6D6- 1
System Diagram .............................................................................................................. 6D6- 2
GENERAL DESCRIPTION
QOS III preheating system features a quick-on glow
plug with thermometer control of the glowing time
and the afterglow time function.
The system consists of a controller, indicator lamp,
thermosensor, vehicle speedsensor, dropping
resistor, relay (2 pcs), and temperature self-control
type glow plug (4 pcs).With the employment of the thermosensor, the
glow time changes according to the engine coolant
temperature, thus allowing optimum starting
conditions to be obtained.
The afterglow time function is controlled by
thermosensor, vehicle speed sensor, and the
engine runstall sensor (charge relay).
SECTION 6D6
QOSIII PREHEATING SYSTEM
CONTENTS

ENGINE MECHANICAL 6A – 3
SERVICE INFORMATION
MAIN DATA AND SPECIFICATION
Engine type Diesel, four cycle water cooled inline
Camshaft type DOHC
Number of cylinders 4
Bore x stroke (mm) 95.4 x 104.9
Total piston displacement (cc) 2999
Compression ratio (to 1) 19.0
For Europe : 18.5
Engine weight (dry) N (kg/lb) 2492 (254/560) (A/T)
For Europe : 2422 (247/545) (A/T)
2649 (270/593) (M/T)
For Europe : 2697 (275/606) (M/T)
Engine idling speed (Reference) RPM 720
Compression pressure kpa (kg/cm
2/psi)-rpm 3040 (31/441)-200
Firing order 1–3–4–2
VALVE SYSTEM
Intake valves open at: B.T.D.C. 3°
close at: A.B.D.C. 57.6°
Exhaust valves open at: B.B.D.C. 56.5°
close at: A.T.D.C. 5°
Valve clearance (at cold) mm (in)
intake: 0.15 (0.006)
exhaust: 0.25 (0.01)
Oil filter Full flow and bypass combined type
Oil capacity (Original factory fill or rebuilt engine) 9.0 liters (7.9 US quarts)
Oil capacity (Service change)
with filter change 6.0 liters (6.3 US quarts)
without filter change 5.0 liters (5.3 US quarts)
Oil cooler Water cooled type
Inter cooler Air cooled type
Turbocharger method
Control method Wastegate control
Lubrication Pressurized control
Cooling method Coolant cooled
Crankshaft
As tufftriding (Nitrizing treatment) is applied to increase
crankshaft strength, crankpins and journals should not
be reground.
Piston Cooling
An oiling jet device for piston cooling is provided in the
lubricating oil circuit from the cylinder block oil gallery
via a check valve.
Take care not to damage any oiling jet when removing
and installing piston and connecting assembly.
Fuel Injection System
The injection system is oil rail type.
Quick On Start 4 System
QOS4 preheating system which features a quick-on
glow plug with thermometer control of the glowing time
and the afterglow time function, is applied.

ENGINE MECHANICAL 6A – 71
12. Immediately install high pressure oil pipe and
tighten to specified torque.
Torque: 80 N·m (8.1 kg·m / 57.9 lb ft)
13. Install cylinder head noise insulator cover.
Refer to “Cylinder Head” in this manual.
14. Install intercooler assembly.
Refer to “Intercooler” in this manual.
15. Install air cleaner cover and air duct.
16. Use TECH2 to rewrite injector data to ECM.
For rewriting method refer to section “Data
Programming in Case of ECM Change” of 6E 4JX1
engine driveability and emissions in this manual.
NOTE:
1) On completion of servicing, bleed air from the
engine inside fuel passage by means of the priming
pump. (The priming pump should be operated more
times than in the case of conventional engines.)
2) As air is in the oil rail, it takes more time to start the
engine. Rough idling may occur while the air is
being bled completely after starting the engine, but
it does not indicate trouble.
The air will be bled and normal engine status will be
reached while the vehicle is driven for about 5 km
or engine is operated for about 5 minutes at 1500 to
2000 rpm.
3) The injector spare part will be provided for group
number B1, B2 and B3 only.