1991 MITSUBISHI MONTERO oil pressure

Automatic Transaxle Fluid ........ 30,000
Belts ............................ 30,000
Coolant .......................... 30,000
Front & Rear Axle Fluid .......... 30,000
Fuel & Vapor Hoses ............... 50,000
Oil
Non-Turbo ........................ 7500
Turbo ............................ 5000
Oil Filter
Non-Turbo ...................... 15,000
Turbo .......................... 10,000
Spark Plugs ...................... 60,000
Timing Belt ...................... 60,000
3000GT
Air Filter ....................... 30,000
Belts ............................ 30,000
Coolant .......................... 30,000
Fuel & Vapor Hoses ............... 50,000
Front & Rear Axle Fluid .......... 30,000
Oil
Non-Turbo ........................ 7500
Turbo ............................ 5000
Oil Filter
Non-Turbo ...................... 15,000
Turbo .......................... 10,000
Spark Plugs ...................... 60,000
Timing Belt ...................... 60,000
(1) - Federal 4WD models only.
( 2) - Federal models only.









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BELT ADJUSTMENT








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Deflection
Application ( 1) In. (mm)
Colt, Colt 200, Mirage & Summit
1.5L ...................................... .28-.35 (7.1-8.9)
1.6L ..................................... .35-.45 (8.9-11.4)
Colt Vista
2.0L ..................................... .28-.40 (7.1-10.2)
Eclipse
1.8L ..................................... .32-.43 (8.1-11.1)
2.0L ..................................... .35-.45 (8.9-11.4)
Galant
Alternator Belt .......................... .35-.45 (8.9-11.4)
A/C Belt .......................................... .32 (8.1)
Power Steering Belt ....................... .24-.35 (6.1-8.9)
Montero
3.0L ...................................... .20-.24 (5.1-6.1)
Pickup & Ram-50
2.4L ...................................... .27-.39 (6.8-9.9)
3.0L ...................................... .32-.39 (8.1-9.9)
Stealth & 3000GT
SOHC
Alternator & Power Steering Belt ........ .24-.35 (6.1-8.9)
A/C Belt ................................ .28-.37 (7.1-9.5)
DOHC
Alternator Belt (With or Without A/C) ... .16-.22 (4.1-5.6)
Power Steering Belt .................... .35-.43 (8.9-11.1)
( 1) - With 22 lbs. (10 kg) pressure applied midway on belt run.

Stud loose in
taper hole ............. A ........... (7) Require repair or
replacement.
Taper hole elongated .... A ........ ( 8) Require replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ........ ( 7) Require replacement.
Wear exceeds
manufacturer's
specifications .......... B ............ Require replacement.
( 1) - If greaseable, grease joint. If problem persists or
joint is non-greaseable, require replacement.
( 2) - Cracked grease boot will allow contaminants to enter
the joint and will accelerate wear.
( 3) - Lack of grease boot will allow contaminants to enter
the joint and will accelerate wear.
( 4) - Torn grease boot will allow contaminants to enter the
joint and will accelerate wear.
( 5) - If manufacturer's procedures for inspection exist, use
those procedures; otherwise, use an approved inspection
method such as the dry park check.
CAUTION: DO NOT use pliers or pry bar to check ball and
socket movement. Use only moderate hand pressure.
( 6) - Excessive looseness is defined as being significant
enough to affect vehicle handling or structural
integrity.
( 7) - Check for damaged taper hole.
( 8) - Check for damaged stud.









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SHOCK ABSORBERS, STRUT CARTRIDGES AND STRUT ASSEMBLIES
You are not required to replace shocks or struts in axle
sets. However, when replacing a shock or strut due to the conditions
that follow, you may suggest replacement of the other shock or strut
on the same axle for improved performance and preventive maintenance.
* Part is close to the end of its useful life
* To extend tire life
* To balance ride and handling
* To improve stopping distance
When replacing steering and/or suspension components which
may affect an alignment angle, you are required to check and adjust
alignment as needed. Refer to the OEM specifications.
Under no circumstances should a technician bend struts or
strut housings.
A vehicle's load-carrying and handling abilities are limited
by its suspension, tires, brakes, and driveline. Installing coil over
shocks or any other load assist device does not increase the vehicle's
load capacity. See the vehicle owner's manual for more details.
NOTE: If vehicle is equipped with original equipment coil over
shocks, apply the conditions for coil springs from the
SPRINGS - COIL, LEAF AND TORSION BAR section of the
STEERING AND SUSPENSION guidelines. If the vehicle is
equipped with add-on coil over shocks, you may suggest
replacing the shocks with standard shocks for any spring-
related condition.
SHOCK ABSORBER, STRUT CARTRIDGE AND STRUT ASSEMBLY INSPECTION









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Circuit Circuit
Application Terminals Terminals
Montero, Pickup 3.0L & Ram-50 3.0L ..... 2 & 4 ............. 1 & 3









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POWER STEERING OIL PRESSURE SWITCH
1) Power steering oil pressure switch is mounted on power
steering pump. Disconnect single wire connector at switch. Start
engine.
2) Connect ohmmeter between switch terminal and ground. If
continuity is present with steering wheel in straight-ahead position,
replace switch. If continuity is not present while turning steering
wheel, perform POWER STEERING IDLE-UP SYSTEM TEST. See IDLE-UP SYSTEMS
under IDLE CONTROL SYSTEM.
THROTTLE POSITION SENSOR
1) TPS is mounted to throttle body, at end of throttle shaft.
Disconnect TPS connector. See Fig. 6. Using ohmmeter, measure total
resistance between TPS connector terminals as specified in TPS
CONNECTOR TERMINAL IDENTIFICATION table. If resistance is not 3500-
6500 ohms, replace TPS.
2) Using an analog (needle-type) ohmmeter, measure variable
resistance between TPS connector terminals as specified in TPS
CONNECTOR TERMINAL IDENTIFICATION table.
3) Operate throttle valve from closed to wide open throttle.
If rate of resistance does not change smoothly within 3500-6500 ohms
throughout range of throttle valve movement, replace TPS.
Fig. 6: TPS Sensor Connector Terminal ID
Courtesy of Mitsubishi Motor Sales of America.
TPS CONNECTOR TERMINAL IDENTIFICATION TABLE









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* Check airflow sensor.
* Check coolant temperature sensor.
* Check idle position switch.
* Check power supply to ECU ground.
* Check fuel pressure.
* Check for disconnected or damaged vacuum hoses.
* Check for control relay malfunction.
* Check for PFI system malfunction.
* Check for fuel pump drive control system malfunction.
* Check for ignition coil malfunction.
* Check for ignition timing malfunction.
* Check for power transistor malfunction.
* Check for fuel injector malfunction.
* Check for ECU malfunction.
* Ensure electrical harness, connectors and wires are not
broken or loose.
ROUGH OR UNSTABLE IDLE
* Check intake air temperature sensor.
* Check purge control solenoid valve (if applicable).
* Check vehicle speed sensor.
* Check engine coolant temperature sensor.
* Check barometric pressure sensor.
* Check ignition switch.
* Check idle position switch.
* Check throttle position sensor.
* Check TDC sensor.
* Check crank angle sensor.
* Check power steering oil pressure switch.
* Check A/C switch and power relay (if applicable).
* Check inhibitor switch.
* Check oxygen sensor.
* Check airflow sensor.
* Check motor position sensor (if equipped).
* Check fuel pressure.
* Check for disconnected or damaged vacuum hoses.
* Check PFI system malfunction.
* Check for stepper motor malfunction (if applicable).
* Check for fuel injector malfunction.
* Check for power transistor malfunction.
* Check for vehicle speed switch malfunction.
* Check for ECU malfunction.
* Ensure electrical harness, connectors and wires are not
broken or loose.
ENGINE HESITATES OR POOR ACCELERATION
* Check intake air temperature sensor.
* Check engine coolant temperature sensor.
* Check barometric pressure sensor.
* Check ignition switch.
* Check ignition coil.
* Check EGR control solenoid valve (if applicable).
* Check idle position switch.
* Check throttle position sensor.
* Check TDC sensor.
* Check crank angle sensor.
* Check power steering oil pressure switch.
* Check A/C switch (if applicable).
* Check inhibitor switch (A/T).
* Check oxygen sensor.
* Check airflow sensor.

* Check motor position sensor (if applicable).
* Check fuel pressure.
* Check for disconnected or damaged vacuum hoses.
* Check for PFI system malfunction.
* Check for stepper motor malfunction (if applicable).
* Check for fuel injector malfunction.
* Check for power transistor malfunction.
* Check for A/C power relay control system malfunction (if
applicable).
* Check for ECU malfunction.
* Ensure electrical harness, connectors and wires are not
broken or loose.
ENGINE SURGES
* Check coolant temperature sensor.
* Check idle position switch.
* Check EGR control solenoid valve (if applicable).
* Check fuel pressure.
* Check for fuel injector malfunction.
DETONATION OR KNOCKING
* Check airflow sensor.
* Check for cooling system problems.
* Check fuel quality.
* Check intake air temperature sensor.
* Check barometric pressure sensor.
* Check ignition coil.
* Check power transistor.
* Check for EGR system malfunction.
POOR FUEL MILEAGE
* Check intake air temperature sensor.
* Check engine coolant temperature sensor.
* Check barometric pressure sensor.
* Check ignition switch.
* Check idle position switch.
* Check throttle position sensor.
* Check TDC sensor.
* Check crank angle sensor.
* Check power steering oil pressure switch.
* Check A/C switch (if applicable).
* Check inhibitor switch (A/T).
* Check oxygen sensor.
* Check airflow sensor.
* Check motor position sensor (if applicable).
* Check fuel pressure.
* Check for PFI system malfunction.
* Check for stepper motor malfunction.
* Check for fuel injector malfunction.
* Check for power transistor malfunction.
INTERMITTENTS
INTERMITTENT PROBLEM DIAGNOSIS
Intermittent fault testing requires duplicating circuit or
component failure to identify problem. These procedures may lead to
computer setting a fault code which may help in diagnosis.
If problem vehicle does not produce fault codes, monitor

input device usage on specific models, see appropriate wiring diagram
in M - WIRING DIAGRAMS.
Air Conditioner Switch
When A/C is turned on, signal is sent to ECU. With engine at
idle, ECU increases idle speed through Idle Speed Control (ISC) motor.\
Airflow Sensor
Incorporated in airflow sensor assembly, airflow sensor is a
Karmen Vortex-type sensor which measures intake airflow rate.
Intake air flows through tunnel in airflow sensor assembly.
Airflow sensor transmits radio frequency signals across direction of
incoming airflow, downstream of vortex. Intake air encounters vortex,
causing turbulence in tunnel.
Turbulence disrupts radio frequency, causing variations in
transmission. Airflow sensor converts frequency transmitted into a
proportionate electrical signal which is sent to ECU.
Airflow Sensor Assembly
Mounted inside air cleaner, incorporates airflow sensor,
atmospheric pressure sensor and intake air temperature sensor.
Atmospheric (Barometric) Pressure Sensor
Incorporated in the airflow sensor assembly, converts
atmospheric pressure to electrical signal which is sent to ECU. ECU
adjusts air/fuel ratio and ignition timing according to altitude.
Coolant Temperature Sensor
Converts coolant temperature to electrical signal for use by
ECU. ECU uses coolant temperature information for controlling fuel
enrichment when engine is cold.
Crankshaft Angle & TDC Sensor Assembly
Assembly is located in distributor on SOHC engines. On DOHC
engines, which use Direct (or Distributorless) Ignition System (DIS)\
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assembly is separate unit mounted in place of distributor. Assembly
consists of triggering disc (mounted on shaft) and stationary optical
sensing unit. Camshaft drives shaft, triggering optical sensing unit.
ECU determines crank angle and TDC based on signals received from
optical sensing unit.
Detonation Sensor (Turbo Only)
Located in cylinder block, senses engine vibration during
detonation (knock). Sensor converts vibration into electrical signal.
ECU retards ignition timing based on this signal.
Engine Speed (Tach Signal)
ECU uses ignition coil tach signal to determine engine speed.
Idle Position Switch
On all DOHC engines and Sigma 3.0L, idle position switch is
separate switch mounted on throttle body. On all other models, idle
position switch is incorporated in ISC motor or throttle position
sensor, depending on vehicle application. When throttle valve is
closed, switch is activated. When throttle valve is at any other
position, switch is deactivated. This input from idle position switch
is used by ECU for controlling fuel delivery time during deceleration.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, ECU timing control function is by-passed, allowing base
timing to be adjusted.

Inhibitor Switch (Automatic Transmission Only)
Inhibitor switch senses position of transmission select
lever, indicating engine load due to automatic transmission
engagement. Based on this signal, ECU commands ISC motor to increase
throttle angle, maintaining optimum idle speed.
Intake Air Temperature Sensor
Incorporated in airflow sensor assembly, this resistor-based
sensor measures temperature of incoming air and supplies air density
information to ECU.
Motor Position Sensor (MPS)
Incorporated in ISC motor (or separate unit on some models),
senses ISC motor plunger position and sends electrical signal to ECU.
Oxygen (O2) Sensor
Located in exhaust system, generates an output voltage.
Output voltage varies with oxygen content of exhaust gas stream. ECU
adjusts air/fuel mixture based on signals from oxygen sensor.
Power Steering Oil Pressure Switch
Detects increase in power steering oil pressure. When power
steering oil pressure increases, switch contacts close, signalling
ECU. ECU commands ISC motor, raising idle speed to compensate for drop
in engine RPM due to power steering load.
TDC Sensor
See CRANKSHAFT ANGLE & TDC SENSOR ASSEMBLY.
Throttle Position Sensor (TPS)
A variable resistor mounted on throttle body. ECU uses
voltage signal received from TPS to determine throttle plate angle.
Vehicle Speed Sensor
Located in speedometer in instrument cluster, uses a reed
switch to sense speedometer gear revolutions. ECU uses gear
revolutions to determine vehicle speed.
OUTPUT SIGNALS
NOTE: Vehicles are equipped with different combinations of
computer-controlled components. Not all components listed
below are used on every vehicle. For theory and operation on
each output component, refer to the system indicated in
brackets after component.
CHECK ENGINE Light
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 Only)
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pressure Regulator
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pump Relay (MPI Control Relay)

See FUEL DELIVERY under FUEL SYSTEM.
Idle Speed Control Servo
See IDLE SPEED under FUEL SYSTEM.
Power Transistor(s) & Ignition Coils
See IGNITION SYSTEMS.
Purge Control Solenoid Valve
See EVAPORATIVE CONTROL under EMISSION SYSTEMS.
Self-Diagnostic Connector
See SELF-DIAGNOSTIC SYSTEM.
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
Consists of an impeller driven by a motor. Pump has an
internal check valve to maintain system pressure and a relief valve to
protect the fuel pressure circuit. Pump receives voltage supply from
Multi-Point Injection (MPI) control relay.
Fuel Pressure Control Solenoid Valve (Turbo Only)
Prevents rough idle due to fuel percolation. On engine
restart, if engine coolant or intake air temperatures reach a preset
value, ECU applies voltage to fuel pressure control solenoid valve for
2 minutes after engine re-start. Valve opens, 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). ECU controls amount\
of fuel metered through injectors based upon information received from
sensors.
IDLE SPEED
Air Conditioner Relay
When A/C is turned on with engine at idle, ECU signals ISC