engine oil MITSUBISHI MONTERO 1998 Owner's Manual

HO2S detects oxygen content in exhaust gas and sends this
information to PCM. PCM uses input signals from HO2S to vary duration
of fuel injection. HO2S heater stabilizes sensor temperature
regardless of exhaust gas temperature to allow for more accurate
exhaust oxygen content readings.
Idle Air Control (IAC) Valve Position Sensor
Sensor is incorporated in IAC motor. Sensor senses IAC motor
plunger position and sends electrical signal to PCM.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, PCM timing control function is by-passed, allowing base
timing to be adjusted.
Intake Air Temperature (IAT) Sensor
IAT sensor is incorporated into airflow sensor assembly. This
resistor-based sensor measures temperature of incoming air and
supplies air density information to PCM.
Knock Sensor (KS)
KS is located in cylinder block and senses engine vibration
during detonation (knock). KS converts vibration into electrical
signal. PCM retards ignition timing based on this signal.
Manifold Differential Pressure (MDP) Sensor
MDP sensor converts negative air pressure in intake manifold
plenum into voltage signals sent to PCM. PCM monitors Exhaust Gas
Recirculation (EGR) system using these signals.
Park/Neutral Position (PNP) Switch (Automatic Transmission)
PNP switch senses position of transmission select lever,
indicating engine load due to automatic transmission engagement. Based
on this signal, PCM commands IAC motor to increase throttle angle,
maintaining optimum idle speed.
Power Steering Oil Pressure Switch
Switch detects increase in power steering oil pressure. When
power steering oil pressure increases, switch contacts close,
signaling PCM. PCM commands IAC motor, raising idle speed to
compensate for drop in engine RPM due to power steering load.
Throttle Position (TP) Sensor
TP sensor is a variable resistor mounted on throttle body.
PCM uses voltage signal from TP sensor to determine throttle plate
angle.
Vehicle Speed Sensor (VSS)
Mounted on transaxle/transmission, VSS sends a pulsing signal
to PCM for vehicle speed calculation. PCM uses this calculation for
cruise control and fuel cut-off.
Volume Airflow (VAF) Sensor
Incorporated into airflow sensor assembly, VAF sensor
measures intake airflow rate. Intake air flows through tunnel in
airflow sensor assembly. VAF sensor sends frequency signal to PCM. PCM
uses signal to adjust fuel injection rate.
OUTPUT SIGNALS
NOTE: Vehicles are equipped with various combinations of
computer-controlled components. Not all components listed
below are used on every vehicle. To determine component

usage on specific models, see appropriate wiring diagram in
L - WIRING DIAGRAMS article. For theory and operation on each
output component, refer to system indicated after component.
Data Link Connector (DLC)
See SELF-DIAGNOSTIC SYSTEM .
EGR Control Solenoid Valve
See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION
SYSTEMS.
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM.
Fuel Pressure Control Solenoid Valve (Turbo)
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pressure Regulator
See FUEL DELIVERY under FUEL SYSTEM.
Idle Air Control (IAC) Motor
See IDLE SPEED under FUEL SYSTEM.
Malfunction Indicator Light
See SELF-DIAGNOSTIC SYSTEM .
Power Transistor(s) & Ignition Coils
See IGNITION SYSTEMS .
Purge Control Solenoid Valve
See EVAPORATIVE CONTROL under EMISSION SYSTEMS.
Wastegate Control Solenoid Valve
See TURBOCHARGED ENGINES under AIR INDUCTION SYSTEM.
FUEL SYSTEM
FUEL DELIVERY
Electric fuel pump, located in gas tank, feeds fuel through
in-tank fuel filter, external fuel filter (located in engine
compartment) and fuel injector rail.
Fuel Pump
Fuel pump consists of a motor-driven impeller. Pump has an
internal check valve to maintain system pressure, and a relief valve
to protect fuel pressure circuit. Pump receives voltage supply from
MFI control relay.
Fuel Pressure Control Solenoid Valve (Turbo)
Valve prevents rough idle due to fuel percolation. On engine
restart, if engine coolant or intake air temperature reaches a preset
value, PCM applies voltage to fuel pressure control solenoid valve for
2 minutes after enginerestart. Valve will open, allowing atmospheric
pressure to be applied to fuel pressure regulator diaphragm. This
allows maximum available fuel pressure at injectors, enriching fuel
mixture and maintaining stable idle at high engine temperatures.
Fuel Pressure Regulator
Located on fuel injector rail, this diaphragm-operated relief
valve adjusts fuel pressure according to engine manifold vacuum.
As engine manifold vacuum increases (closed throttle), fuel

pressure regulator diaphragm opens relief valve, allowing pressure to
bleed off through fuel return line, reducing fuel pressure.
As engine manifold vacuum decreases (open throttle), fuel
pressure regulator diaphragm closes valve, preventing pressure from
bleeding off through fuel return line, increasing fuel pressure.
FUEL CONTROL
Fuel Injectors
Fuel is supplied to engine through electronically pulsed
(timed) injector valves located on fuel rail(s). PCM controls amount\
of fuel metered through injectors based on information received from
sensors.
IDLE SPEED
Air Conditioning (A/C) Relay
When A/C is turned on with engine at idle, PCM signals IAC
motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, PCM momentarily opens A/C relay
circuit.
Idle Air Control (IAC) Motor
Motor controls pintle-type air valve to regulate volume of
intake air at idle.
During start mode, PCM controls idle intake air volume
according to Engine Coolant Temperature (ECT) sensor input. After
starting, with idle position switch activated (throttle closed), fast
idle speed is controlled by IAC motor and fast idle air control valve
(if equipped).
When idle switch is deactivated (throttle open), IAC motor
moves to a preset position in accordance with ECT sensor input.
PCM signals IAC motor to increase engine RPM in the following
situations: A/T (if applicable) is shifted from Neutral to Drive, A/C
is turned on, or power steering pressure reaches a preset value.
IGNITION SYSTEMS
DIRECT IGNITION SYSTEM (DIS)
Depending on number of cylinders, ignition system is a 2 or
3-coil, distributorless ignition system. On Eclipse (Turbo) and DOHC
V6 engines, Camshaft Position (CMP) sensor is located beside camshaft,\
in front of engine. On all other engines equipped with DIS, CMP sensor
is a separate unit mounted in place of distributor. On DOHC 4-
cylinder, DOHC V6 and 1.8L 4-cylinder engines with California
emissions, Crankshaft Position (CKP) sensor is located beside
crankshaft, in front of engine. PCM determines TDC based on pulse
signals received from sensors and then controls MFI and ignition
timing.
Power Transistors & Ignition Coils
Based on crankshaft position and CMP sensor inputs, PCM
controls timing and directly activates each power transistor to fire
coils. On 4-cylinder engines, power transistor "A" controls primary
current of ignition coil "A" to fire spark plugs on cylinders No. 1
and No. 4 at the same time. Power transistor "B" controls primary
current of ignition coil "B" to fire spark plugs on cylinders No. 2
and No. 3 at the same time. On V6 engines, companion cylinders No. 1
and 4, 2 and 5, and 3 and 6 are fired together.
On all models, although each coil fires 2 plugs at the same
time, ignition takes place in only one cylinder, since the other

cylinder is on its exhaust stroke when plug fires.
HALL EFFECT IGNITION SYSTEM
This system is equipped with a Hall Effect distributor.
Shutter(s) attached to distributor shaft rotate through distributor
Hall Effect switch, also referred to as a Camshaft Position (CMP)
sensor, which contains a distributor pick-up (a Hall Effect device and
magnet). As shutter blade(s) pass through pick-up, magnetic field is
interrupted and voltage is toggled between high and low. PCM uses this
data along with Crankshaft Position (CKP) sensor data to control
ignition timing and injector pulse width to maintain optimum
driveability.
Power Transistor & Ignition Coil
Power transistor is mounted inside distributor with disc and
optical sensing unit. When ignition is on, ignition coil primary
circuit is energized. As distributor shaft rotates, disc rotates,
triggering optical sensing unit. PCM receives signals from optical
sensing unit. Signals are converted and sent to power transistor,
interrupting primary current flow and inducing secondary voltage.
IGNITION TIMING CONTROL SYSTEM
Ignition timing is controlled by PCM. PCM adjusts timing
based on various conditions such as engine temperature, altitude and
detonation.
EMISSION SYSTEMS
EXHAUST GAS RECIRCULATION (EGR) CONTROL
Federal Emissions (Non-Turbo)
To lower oxides of nitrogen (NOx) exhaust emissions, a non-
computer controlled exhaust gas recirculation system is used. EGR
operation is controlled by throttle body ported vacuum. Vacuum is
routed through vacuum control valve to prevent EGR operation at low
engine temperatures.
Spring pressure holds EGR valve closed during low vacuum
conditions (engine idling or wide open throttle). When vacuum pressure\
increases and overcomes EGR spring pressure, EGR valve is lifted to
allow exhaust gases to flow into intake manifold for combustion.
California Emissions & Turbo
PCM controls EGR operation by activating EGR control solenoid
valve according to engine load. When engine is cold, PCM signals EGR
control solenoid valve to deactivate EGR.
EGR Control Solenoid Valve
Valve denies or allows vacuum supply to EGR valve based on
PCM commands.
EVAPORATIVE CONTROL
Fuel evaporation system prevents fuel vapor from entering
atmosphere. System consists of special fuel tank with vapor separator
tanks (if equipped), vacuum relief filler cap, overfill limiter (2-wa\
y
valve), fuel check valve, thermovalve (if equipped), charcoal
canister, purge control valve, purge control solenoid valve, and
connecting lines and hoses.
Purge Control Solenoid Valve

When engine is off, fuel vapors are vented into charcoal
canister. When engine is warmed to normal operating temperature and
running at speeds greater than idle, PCM energizes purge control
solenoid valve, allowing vacuum to purge valve.
Canister vapors are then drawn through solenoid valve into
intake manifold for burning. Purge control solenoid valve remains
closed during idle and engine warm-up to reduce HC (hydrocarbons) and
CO (carbon monoxide) emissions.
POSITIVE CRANKCASE VENTILATION (PCV) VALVE
PCV valve operates in closed crankcase ventilation system.
Closed crankcase ventilation system consists of PCV valve, oil
separator, breather and ventilation hoses.
PCV valve is a one-way check valve located in valve cover.
When engine is running, manifold vacuum pulls PCV valve open, allowing
crankcase fumes to enter intake manifold. If engine backfires through
intake manifold, PCV valve closes to prevent crankcase combustion.
SELF-DIAGNOSTIC SYSTEM
NOTE: PCM diagnostic memory is retained by direct power supply
from battery. Memory is not erased by turning off ignition,
but it will be erased if battery or PCM is disconnected.
Self-diagnostic system monitors input and output signals
through the Data Link Connector (DLC). Diagnostic Trouble Codes (DTCs\
)
can only be read using a scan tester. For additional information, see
G - TESTS W/CODES article.
Malfunction Indicator Light (MIL)
MIL (CHECK ENGINE light) comes on when ignition is turned on.\
MIL remains on for several seconds after engine has started. If an
abnormal input signal occurs, MIL comes on and code is stored in
memory. If an abnormal input signal returns to normal, PCM turns MIL
off, but code remains stored in memory until it is cleared. If
ignition is turned on again, MIL will not come on until PCM detects
malfunction during system operation.

Center Differential Lock Operation
Detection Switch On transfer case.
Dual Pressure Switch On high pressure line, on
receiver-drier.
Engine Coolant Temperature Switch Top right front of engine.
Free Wheel Engage Switch Right side of engine
compartment.
High Range/Low Range Detection Switch On transfer case.
Low Range Operation Detection Switch On transfer case.
Oil Pressure Switch Lower left front of engine.
Parking Brake Switch At base of parking brake
lever.
Power Steering Pressure Switch On power steering pump.
Rear Differential Lock Detection
Switch Under rear of vehicle, on
differential.
Reed Switch Integral with speedometer.
Seat Belt Switch On driver-side seat belt
buckle.
Stoplight Switch On bracket, above brake pedal.
2WD/4WD Detection Switch On transfer case.
4WD Operation Detection Switch On transfer case.









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MISCELLANEOUS









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Component Component Location








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Amplifier Under center console, below
floor.
Data Link Connector (DLC) Behind left side of dash,
near relay box.

Fuel Pump Check Connector Taped to wiring harness, on
right side of firewall.
Ignition Timing Adjustment
Connector Taped to wiring harness, on
right side of firewall.
Ignition Coil Top left side of engine.

Ignition Power Transistor Top left side of engine, next
to ignition coil.
IOD Or Storage Connector In engine compartment relay
box.
Noise Capacitor Top of engine.
Resistor On blower motor housing.









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rust may be removed using bead blasting method. Components must be
free of oil and grease prior to bead blasting. Beads will stick to
grease or oil soaked areas causing area not to be cleaned.
Use air pressure to remove all trapped residual beads from
components after cleaning. After cleaning internal engine parts made
of aluminum, wash thoroughly with hot soapy water. Component must be
thoroughly cleaned as glass beads will enter engine oil resulting in
bearing damage.
CHEMICAL CLEANING
Solvent tank is used for cleaning oily residue from
components. Solvent blasting sprays solvent through a siphon gun using
compressed air.
The hot tank, using heated caustic solvents, is used for
cleaning ferrous materials only. DO NOT clean aluminum parts such as
cylinder heads, bearings or other soft metals using the hot tank.
After cleaning, flush parts with hot water.
A non-ferrous part will be ruined and caustic solution will
be diluted if placed in the hot tank. Always use eye protection and
gloves when using the hot tank.
Use of a cold tank is for cleaning of aluminum cylinder
heads, carburetors and other soft metals. A less caustic and unheated
solution is used. Parts may be lift in the tank for several hours
without damage. After cleaning, flush parts with hot water.
Steam cleaning, with boiling hot water sprayed at high
pressure, is recommended as the final cleaning process when using
either hot or cold tank cleaning.
COMPONENT CLEANING
* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
SHEET METAL PARTS
Examples of sheet metal parts are the rocker covers, front
and side covers, oil pan and bellhousing dust cover. Glass bead
blasting or hot tank may be used for cleaning.
Ensure all mating surfaces are flat. Deformed surfaces should
be straightened. Check all sheet metal parts for cracks and dents.
INTAKE & EXHAUST MANIFOLDS
Using solvent cleaning or bead blasting, clean manifolds for
inspection. If the intake manifold has an exhaust crossover, all
carbon deposits must be removed. Inspect manifolds for cracks, burned
or eroded areas, corrosion and damage to fasteners.
Exhaust heat and products of combustion cause threads of
fasteners to corrode. Replace studs and bolts as necessary. On "V"
type intake manifolds, the sheet metal oil shield must be removed for
proper cleaning and inspection. Ensure that all manifold parting
surfaces are flat and free of burrs.
CYLINDER HEAD REPLACEMENT
* PLEASE READ THIS FIRST *

NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
REMOVAL
Remove intake and exhaust manifolds and valve cover. Cylinder
head and camshaft carrier bolts (if equipped), should be removed only
when the engine is cold. On many aluminum cylinder heads, removal
while hot will cause cylinder head warpage. Mark rocker arm or
overhead cam components for location.
Remove rocker arm components or overhead cam components.
Components must be installed in original location. Individual design
rocker arms may utilize shafts, ball-type pedestal mounts or no rocker
arms. For all design types, wire components together and identify
according to the corresponding valve. Remove cylinder head bolts.
Note length and location. Some applications require cylinder head
bolts be removed in proper sequence to prevent cylinder head damage.
See Fig. 1 . Remove cylinder head.
Fig. 1: Typical Cylinder Head Tightening or Loosening Sequence
This Graphic For General Information Only
INSTALLATION
Ensure all surfaces and head bolts are clean. Check that head
bolt holes of cylinder block are clean and dry to prevent block damage
when bolts are tightened. Clean threads with tap to ensure accurate
bolt torque.
Install head gasket on cylinder block. Some manufacturer's
may recommend sealant be applied to head gasket prior to installation.
Note that all holes are aligned. Some gasket applications may be
marked so certain area faces upward. Install cylinder head using care
not to damage head gasket. Ensure cylinder head is fully seated on
cylinder block.
Some applications require head bolts be coated with sealant
prior to installation. This is done if head bolts are exposed to water
passages. Some applications require head bolts be coated with light
coat of engine oil.