fuel MITSUBISHI MONTERO 1991 User Guide
[x] Cancel search | Manufacturer: MITSUBISHI, Model Year: 1991, Model line: MONTERO, Model: MITSUBISHI MONTERO 1991Pages: 1333, PDF Size: 24.61 MB
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F - B ASIC T E STIN G
1991 M it s u bis h i M onte ro
1991 ENGINE PERFORMANCE
Basic Diagnostic Procedures
Chrysler; Colt, Colt 200, Colt Vista, Ram-50, Stealth,
Summit
Mitsubishi; Eclipse, Galant, Mirage, Montero, Pickup, 3000GT
INTRODUCTION
The following diagnostic steps will help prevent overlooking
a simple problem. This is also where to begin diagnosis for a no start
condition. First step in diagnosing any driveability problem is
verifying customer's complaint with a test drive under conditions
problem reportedly occurred.
Before entering self-diagnostics, perform a careful and
complete visual inspection. Most engine control problems result from
mechanical breakdowns, poor electrical connections or
damaged/misrouted vacuum hoses. Before condemning computerized system,
perform each test listed in article.
NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM)\
with a minimum 10-megohm input impedance, unless stated
otherwise in test procedure.
PRELIMINARY INSPECTION & ADJUSTMENTS
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed,
stretched, cut or pinched wiring. Ensure electrical connectors fit
tightly and are not corroded. Ensure distributor cap and rotor are
free of cracks, carbon trails or contamination. Ensure vacuum hoses
are properly routed and not pinched or cut. See M - VACUUM DIAGRAMS
article in the ENGINE PERFORMANCE Section to verify routing and
connections (if necessary). Inspect air induction system for possible
vacuum leaks.
MECHANICAL INSPECTION
Compression
Check engine mechanical condition with a compression gauge,
vacuum gauge, or an engine analyzer. See engine analyzer manual for
specific instructions.
WARNING: DO NOT use ignition switch during compression tests. Use a
remote starter to crank engine. Fuel injectors on many models
are triggered by ignition switch during cranking mode, which
can create a fire hazard or contaminate engine's oiling
system.
COMPRESSION SPECIFICATIONS TABLE (1)
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Application Specification
psi (kg/cm)
1.5L (VIN X) .............................. 137 (9.6)
1.6L (VIN Y) ............................. 171 (12.0)
1.8L (VIN T) .............................. 131 (9.2)
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2.0L (VIN R) DOHC ......................... 137 (9.6)
2.0L (VIN U) DOHC Turbo ................... 114 (8.0)
2.0L (VIN V) SOHC ......................... 119 (8.4)
2.4L (VIN W) SOHC ......................... 119 (8.4)
3.0L (VIN S) SOHC ......................... 119 (8.4)
3.0L (VIN B) DOHC ......................... 139 (9.8)
3.0L (VIN C) DOHC Turbo ................... 115 (8.1)
(1) - Maximum variation between cylinders 14 psi
(1.0 kg/cm
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Exhaust System Backpressure
Exhaust system can be checked with a vacuum or pressure
gauge. Remove O2 sensor or air injection check valve (if equipped).
Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If
exhaust system backpressure is greater than 1 3/4-2 psi, exhaust
system or catalytic converter is plugged. If a vacuum gauge is used,
connect vacuum gauge hose to intake manifold vacuum port and start
engine. Observe vacuum gauge. Open throttle part way and hold steady.
If vacuum gauge reading slowly drops after stabilizing, exhaust system
should be checked for a restriction.
FUEL PRESSURE
Basic diagnosis of fuel system should begin with determining
fuel system pressure.
FUEL INJECTED ENGINES
WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel
injection-related component. DO NOT allow fuel to contact
engine or electrical components.
Fuel Pressure
1) On all models except Colt and Mirage, disconnect fuel pump
harness connector at fuel tank. On Colt and Mirage, remove rear seat
cushion to disconnect fuel pump harness connector.
2) On all models, start engine. Let engine run until it
stops. Turn ignition off. Disconnect negative battery terminal.
Connect fuel pump harness connector.
WARNING: Before disconnecting high pressure fuel hose at fuel delivery
pipe, cover fuel hose connection with a rag. Some residual
fuel pressure may still be in system.
3) On Galant 2.0L (DOHC), remove brace for access to high
pressure fuel delivery pipe. On all engines, disconnect high pressure
fuel hose at fuel delivery pipe.
4) Connect fuel pressure gauge with adapter between fuel
delivery pipe and high pressure hose. See Fig. 1. Connect negative
battery terminal. Connect battery voltage to fuel pump test terminal.
See FUEL PUMP TEST TERMINAL LOCATION table. Ensure no fuel leaks are
present. Disconnect battery voltage to fuel pump test terminal.
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Fig. 1: Fuel Pressure Testing Connection ID (Typical Fuel Inj. Eng.)
Courtesy of Mitsubishi Motor Sales of America.
5) Start engine and let idle. Measure fuel pressure with
vacuum hose connected to fuel pressure regulator. Record fuel pressure
reading. Disconnect and plug vacuum hose from fuel pressure regulator.
Record fuel pressure reading. See REGULATED FUEL PRESSURE table.
6) Check for fuel pressure in fuel return hose by gently
pinching hose while increasing engine speed. If fuel volume is low,
fuel pressure in return hose will not be felt. Increase engine speed
to 2500-3000 RPM, 2-3 times. Return engine to idle. Fuel pressure
should not drop when engine is returned to idle.
7) Turn engine off. Ensure fuel pressure reading does not
decrease within 2 minutes. If a decrease is noted, monitor speed of
decrease.
8) If fuel pressure is lower than specification, fuel
pressure drops at idle after increasing engine speed to 2500-3000 RPM,
or no fuel pressure in fuel return hose can be felt, check for clogged
fuel filter, faulty fuel pressure regulator, or fuel pump.
9) If fuel pressure is higher than specification, check for a
faulty fuel pressure regulator or plugged fuel return line. If fuel
pressure does not change when vacuum hose to regulator is connected or
disconnected, check for a leaking or clogged vacuum hose to fuel
pressure regulator or faulty fuel pressure regulator.
10) If fuel pressure decreases suddenly after engine is
stopped, check valve within fuel pump is not seated. Replace fuel
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pump. If fuel pressure drops slowly, fuel injector is leaking or fuel
pressure regulator valve seat is leaking. Check for faulty fuel
injector or fuel pressure regulator. Repair as required.
11) When fuel pressure test is complete, repeat fuel pressure
release procedure in steps 1) and 2) before disconnecting fuel
pressure gauge. Install new "O" ring at end of high pressure hose.
Check for fuel leaks.
FUEL PUMP TEST TERMINAL LOCATION TABLE
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Application Wire Color Location
Colt, Colt 200 ......... BLK/WHT .............. Center Of Firewall
Colt Vista ............. BLK/WHT ........ Right Center Of Firewall
Eclipse ................ BLK/WHT .......... Rear Of Battery Compt.
Galant ................. YEL/GRN ........... Left Rear Eng. Compt.
Mirage 1.5L ............ BLK/WHT .............. Center Of Firewall
Mirage 1.6L ............ BLK/BLU .............. Center Of Firewall
Montero .................. WHT .......... Right Center Of Firewall
Pickup ................. BLK/BLU ....... Right Side Of Eng. Compt.
Precis ................... YEL ............. Left Rear Eng. Compt.
Summit ................. BLK/WHT .............. Center Of Firewall
Ram-50 ................. BLK/BLU ....... Right Side Of Eng. Compt.
Stealth, 3000GT ........ BLK/BLU .......... Rear Of Battery Compt.
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REGULATED FUEL PRESSURE TABLE \
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At Idle At Idle
w/Vacuum w/o Vacuum
Application psi (kg/cm
) psi (kg/cm)
Non-Turbo .................. 38 (2.7) ....... 47-50 (3.3-3.5)
Turbo
Except Eclipse A/T ....... 27 (1.9) ....... 36-38 (2.5-2.7)
Eclipse A/T .............. 33 (2.3) ....... 36-38 (2.9-3.2)
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Control Relay
Multipurpose relay switches power to vehicle sensors and
actuators including airflow sensor, crank angle sensor, idle speed
control, injectors and fuel pump. When ignition switch is turned to ON
position, ECU energizes coils controlling injectors, airflow sensor
and idle speed control. When ignition switch is turned to START
position, ECU energizes coils (through inhibitor switch on A/T models)\
to supply power to fuel pump. Relay failure will cause a no-start
condition. For testing procedure, see SYSTEM & COMPONENT TESTING
article.
IGNITION CHECKS
SPARK
Check for spark at coil wire (if applicable) and at each
spark plug wire using a high output spark tester. Check spark plug
wire resistance on suspect wires. For wire resistance specification,
see C - SPECIFICATIONS article in the ENGINE PERFORMANCE Section.
CRANK ANGLE SENSOR
For crank angle sensor testing procedure on all models except
Ram-50, Stealth, Eclipse, Laser, Pickup and 3000GT, see TEST NS-5:
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![MITSUBISHI MONTERO 1991 User Guide same axle to eliminate uneven braking behavior. Always wash drums
after servicing or before installing.
DRUM INSPECTION
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\](/img/19/57332/w960_57332-185.png "MITSUBISHI MONTERO 1991 User Guide same axle to eliminate uneven braking behavior. Always wash drums
after servicing or before installing.
DRUM INSPECTION
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same axle to eliminate uneven braking behavior. Always wash drums
after servicing or before installing.
DRUM INSPECTION
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Condition Code Procedure
Balance weight missing .. .. ........ No service suggested or
required.
Bell-mouthed, affecting
performance ............ A ....... Require reconditioning or
replacement.
Cooling fin broken ...... .. ........ No service suggested or
required.
Cracked ................. B ............ Require replacement.
Drum diameter is greater
than OEM "machine to"
specifications but less
than "discard at"
specifications, and the
drum does not require
reconditioning ......... 1 ........ (1) Suggest replacement.
Drum diameter will exceed
OEM "machine to"
specifications after
required
reconditioning ......... B ........ ( 2) Require replacement.
Hard-spotted ............ 2 ....... Suggest reconditioning or
replacement.
Measured diameter is
greater than OEM discard
specifications ......... B ............ Require replacement.
Out-of-round (runout),
affecting performance .. A ....... Require reconditioning or
replacement.
Out-of-round (runout),
exceeding manufacturer's
specifications ......... B ....... Require reconditioning or
replacement.
Scored .................. B ....... Require reconditioning or
replacement.
Surface threaded due to
improper machining ..... B ....... Require reconditioning or
replacement.
Tapered, affecting
performance ............ A ....... Require reconditioning or
replacement.
( 1) - Only applies to vehicles for which OEM "machine to"
specifications exist. If OEM does not supply "machine to"
specifications, the drum may be worn to discard
specifications.
( 2) - If OEM does not supply "machine to" specifications, you
may machine to discard specifications.
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ELECTRICAL PUMPS AND MOTORS
Copied fuel pump conditions from engine UIGs & deleted
pulsator from leaking conditions.
ELECTRICAL PUMP AND MOTOR INSPECTION
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NOTE: Copied Vehicle Speed Sensors from Engine UIGs & added
Air Gap incorrect, loose, and wire lead misrouted. For
"contaminated" removed coolant & fuel examples from note.
SPEED SENSOR INSPECTION
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Condition Code Procedure
Air gap incorrect ....... B ....... (1) Require adjustment or
replacement.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware
threads damaged ........ A ... Require repair or replacement
of hardware.
Attaching hardware
threads stripped
(threads missing) ...... A .. Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking ........... A .. Require repair or replacement.
Connector melted ........ A ........... ( 2) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.
Contaminated ............ A ........... ( 3) Require repair or
replacement.
Inoperative ............. B ........... ( 4) Require repair or
replacement. Further
inspection required.
Lead routing incorrect .. B ..... Require rerouting according
to vehicle manufacturer's
specifications.
Leaking ................. A .. Require repair or replacement.
Loose ................... A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Resistance out of
specification .......... B .. Require repair or replacement.
Sensor housing cracked .. 2 ............ Suggest replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned,
affecting performance .. A ........... ( 2) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose,
affecting performance .. B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped
(threads missing) ...... A ............ Require replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead misrouted ..... B . Require re-routing according to
vehicle manufacturer's
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CO M PU TE R R ELE A R N P R O CED URES
1991 M it s u bis h i M onte ro
GENERAL INFORMATION
Computer Relearn Procedures
All Models
* PLEASE READ THIS FIRST *
The following general procedures are to be used if
driveability problems are encountered after power loss or battery has
been disconnected. These procedures may provide an aid in eliminating
these problems.
To reduce the possibility of complaints, after any service
which requires battery power to be disconnected, vehicle should be
road tested.
COMPUTER RELEARN PROCEDURES
Vehicles equipped with engine or transmission computers may
require a relearn procedure after vehicle battery is disconnected.
Many vehicle computers memorize and store vehicle operation patterns
for optimum driveability and performance. When vehicle battery is
disconnected, this memory is lost. The computer will use default data
until new data from each key start is stored. As computer memorizes
vehicle operation for each new key start, driveability is restored.
Vehicle computers may memorize vehicles operation patterns for 40 of
more key starts.
Customers often complain of driveability problems during
relearn stage because vehicle acts differently then before being
serviced. Depending on type and make of vehicle and how it is
equipped, the following complaints (driveability problems) may exist:
* Harsh Or Poor Shift Quality
* Rough Or Unstable Idle
* Hesitation Or Stumble
* Rich Or Lean Running
* Poor Fuel Mileage
These symptoms and complaints should disappear after a number
of drive cycles have been memorized. To reduce the possibility of
complaints, after any service which requires battery power to be
disconnected, vehicle should be road tested. If a specific relearn
procedure is not available, the following procedure may be used:
Automatic Transmission
* Set parking brake, start engine in "P" or "N" position.
Warm-up vehicle to normal operating temperature or until
cooling fan cycles.
* Allow vehicle to idle for one minute in "N" position. Select
"D" and allow engine to idle for one minute.
* Accelerate at normal throttle position (20-50%) until vehicle
shifts into top gear.
* Cruise at light to medium throttle.
* Decelerate to a stop, allowing vehicle to downshift, and use
brakes normally.
* Process may be repeated as necessary.
Manual Transmission
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Damaged, affecting
performance ............ A ............ Require replacement.
Missing ................. C ............ Require replacement.
Worn, affecting
performance ............ A ............ Require replacement.
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LUBRICANTS
See FLUIDS AND LUBRICANTS .
METAL-CLAD SEALS
See SEALS.
METALASTIC JOINTS
See RUBBER JOINTS (METALASTIC) .
MODULATOR PINS
MODULATOR PIN INSPECTION \
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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Missing ................. C ............ Require replacement.
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MODULATORS
MODULATOR INSPECTION \
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Condition Code Procedure
Bent, affecting
performance ............ A ............ Require replacement.
Contaminated (water, fuel,
etc.) .................. A ........ ( 1) Require replacement.
Housing cracked ......... A ............ Require replacement.
Inoperative ............. A ........ ( 2) Require replacement.
Leaking fluid
externally ............. A .. Require repair or replacement.
Leaking fluid
internally ............. A ............ Require replacement.
Leaking vacuum .......... A ............ Require replacement.
Nipple broken ........... A ............ Require replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
( 1) - Further inspection is required to determine the cause
of the contamination.
( 2) - Inoperative includes intermittent operation or out of OEM
specification.
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MOUNTS (ENGINE, TRANSAXLE AND TRANSMISSION)
MOUNT (ENGINE, TRANSAXLE AND TRANSMISSION) INSPECTION \
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Ignition Timing Adjustment Under wiper motor.
Fuel Pump Check In right side kick panel.
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Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Refer to manufacturer's diagnostic trouble code procedure
and require repair or replacement of affected
component(s).
( 2) - Determine cause and correct prior to repair or replacement
of part.
( 3) - Determine source of contamination, such as engine
coolant, fuel, metal particles, or water. Require
repair or replacement.
( 4) - Inoperative includes intermittent operation or out of OEM
specification. Some components may be serviceable; check
for accepted cleaning procedure.
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CRUISE CONTROL BRAKE SWITCHES
See SWITCHES.
CRUISE CONTROL CABLES
See CRUISE CONTROL LINKAGES AND CABLES .
CRUISE CONTROL CLUTCH SWITCHES
See SWITCHES.
CRUISE CONTROL LINKAGES AND CABLES
CRUISE CONTROL LINKAGE AND CABLE INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bent .................... A .. Require repair or replacement.
Binding ................. A .. Require repair or replacement.
Bracket bent, affecting
performance ............ A .. Require repair or replacement.
Bracket bent, not
affecting performance .. .. ........ No service suggested or
required.
Bracket broken, affecting
performance ............ A ............ Require replacement.
Bracket broken, not
affecting performance .. .. ........ No service suggested or
required.
Bracket corroded,
affecting performance .. A .. Require repair or replacement.
Bracket corroded, not
affecting performance .. 2 .. Suggest repair or replacement.