1998 MITSUBISHI MONTERO check engine light

completion of the inspection. Magnetic particle inspection applies to
ferrous materials only.
PENETRANT INSPECTION
Zyglo
The Zyglo process coats the material with a fluorescent dye
penetrant. The part is often warmed to expand cracks that will be
penetrated by the dye. When the coated part is subjected to inspection
with a blacklight, a crack will glow brightly. Developing solution
is often used to enhance results. Parts made of any material, such as
aluminum cylinder heads or plastics, may be tested using this process.
Dye Check
Penetrating dye is sprayed on the previously cleaned
component. Dye is left on component for 5-45 minutes, depending upon
material density. Component is then wiped clean and sprayed with a
developing solution. Surface cracks will show up as a bright line.
ULTRASONIC INSPECTION
If an expensive part is suspected of internal cracking,
Ultrasonic testing is used. Sound waves are used for component
inspection.
X-RAY INSPECTION
This form of inspection is used on highly stressed
components. X-ray inspection maybe used to detect internal and
external flaws in any material.
PRESSURE TESTING
Cylinder heads can be tested for cracks using a pressure
tester. Pressure testing is performed by plugging all but one of the
holes in the head and injecting air or water into the open passage.
Leaks are indicated by the appearance of wet or damp areas when using
water. When air is used, it is necessary to spray the head surface
with a soap solution. Bubbles will indicate a leak. Cylinder head may
also be submerged in water heated to specified temperature to check
for cracks created during heat expansion.
CLEANING PROCEDURES
* 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.
GENERAL
All components of an engine do not have the same cleaning
requirements. Physical methods include bead blasting and manual
removal. Chemical methods include solvent blast, solvent tank, hot
tank, cold tank and steam cleaning of components.
BEAD BLASTING
Manual removal of deposits may be required prior to bead
blasting, followed by some other cleaning method. Carbon, paint and

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.

during manufacture, some new type valves cannot be reground.
Resurface valve on proper angle specification using valve
grinding machine. Follow manufacturer's instructions for valve
grinding machine. Specifications may indicate a different valve face
angle than seat angle.
Measure valve margin after grinding. Replace valve if not
within specification. Valve stem tip can be refinished using valve
grinding machine.
Valve Lapping
During valve lapping of recent designed valves, be sure to
follow manufacturers recommendations. Surface hardening and materials
used with some valves do not permit lapping. Lapping process will
remove excessive amounts of the hardened surface.
Valve lapping is done to ensure adequate sealing between
valve face and seat. Use either a hand drill or lapping stick with
suction cup attached.
Moisten and attach suction cup to valve. Lubricate valve stem
and guide. Apply a thin coat of fine valve grinding compound between
valve and seat. Rotate lapping tool between the palms or with hand
drill.
Lift valve upward off the seat and change position often.
This is done to prevent grooving of valve seat. Lap valve until a
smooth polished seat is obtained. Thoroughly clean grinding compound
from components. Valve to valve seat concentricity should be checked.
See VALVE SEAT CONCENTRICITY.
CAUTION: Valve guides must be in good condition and free of carbon
deposits prior to valve seat grinding. Some engines contain
an induction hardened valve seat. Excessive material removal
will damage valve seats.
Valve Seat Grinding
Select coarse stone of correct size and angle for seat to be
ground. Ensure stone is true and has a smooth surface. Select correct
size pilot for valve guide dimension. Install pilot in valve guide.
Lightly lubricate pilot shaft. Install stone on pilot. Move stone off
and on the seat approximately 2 times per second during grinding
operation.
Select a fine stone to finish grinding operation. Grinding
stones with 30 and 60 degree angles are used to center and narrow the
valve seat as required. See Fig. 10.
Fig. 10: Adjusting Valve Seat Width - Typical
This Graphic For General Information Only
Valve Seat Replacement
Replacement of valve seat inserts is done by cutting out

over connecting rod bolts. Install piston and connecting rod assembly.
Ensure piston notch, arrow or "FRONT" mark is toward front of engine.
See Fig. 17 .
Fig. 17: Installing Piston & Connecting Rod Assembly - Typical
This Graphic For General Information Only
Carefully tap piston into cylinder until rod bearing is
seated on crankshaft journal. Remove protectors. Install rod cap and
bearing. Lightly tighten connecting rod bolts. Repeat procedure for
remaining cylinders. Check bearing clearance. See
MAIN & CONNECTING ROD BEARING CLEARANCE in this article.
Once clearance is checked, lubricate journals and bearings.
Install bearing caps. Ensure marks are aligned on connecting rod and
cap. Tighten rod nuts or bolts to specification. Ensure rod moves
freely on crankshaft. Check connecting rod side clearance. See
CONNECTING ROD SIDE CLEARANCE in this article.
CONNECTING ROD SIDE CLEARANCE
Position connecting rod toward one side of crankshaft as far
as possible. Using feeler gauge, measure clearance between side of
connecting rod and crankshaft. See Fig. 18. Clearance must be within
specifications.

* Load Value (Displayed As Percent)
* Engine Coolant Temperature
* Short Term Fuel Trim (Displayed As Percent)
* Long Term Fuel Trim (Displayed As Percent)
* MAP Vacuum
* Engine RPM
* Vehicle Speed Sensor
* DTC During Data Recording
SELF-DIAGNOSTIC SYSTEM
SERVICE PRECAUTIONS
Before proceeding with diagnosis, following precautions must
be observed:
* Ensure vehicle has a fully charged battery and functional
charging system.
* Visually inspect connectors and circuit wiring being worked
on.
* DO NOT disconnect battery or PCM. This will erase any DTCs
stored in PCM.
* DO NOT cause short circuits when performing electrical tests.
This will set additional DTCs, making diagnosis of original
problem more difficult.
* DO NOT use a test light in place of a voltmeter.
* When checking for spark, ensure coil wire is NOT more than
1/4" from chassis ground. If coil wire is more than 1/4" from
chassis ground, damage to vehicle electronics and/or PCM may
result.
* DO NOT prolong testing of fuel injectors. Engine may
hydrostatically (liquid) lock.
* When a vehicle has multiple DTCs, always repair lowest number
DTC first.
VISUAL INSPECTION
Most driveability problems in the engine control system
result from faulty wiring, poor electrical connections or leaking air
and vacuum hose connections. To avoid unnecessary component testing,
perform a visual inspection before beginning self-diagnostic tests.
ENTERING ON-BOARD DIAGNOSTICS
NOTE: DO NOT skip any steps in self-diagnostic tests or incorrect
diagnosis may result. Ensure self-diagnostic test applies to
vehicle being tested.
DTCs may be retrieved by using a scan tool only. Proceed to
DTC retrieval method.
NOTE: Although other scan tools are available, Mitsubishi
recommends using Multi-Use Tester II (MUT II) scan tool.
Using Scan Tool
1) Refer to manufacturer's operation manual for instructions
in use of scan tool. Before entering on-board diagnostics, see
SERVICE PRECAUTIONS . Locate Data Link Connector (DLC) under instrument
panel, near steering column.
2) Turn ignition switch to OFF position. Connect scan tool to
DLC. Turn ignition switch to ON position. Read and record scan tool
self-diagnostic output. Proceed to TROUBLE CODE DEFINITION.

special patterns probe to VAF sensor connector terminal No. 3 or to
PCM connector terminal No. 61.
2) Start engine. Verify waveform high frequency and low
frequency patterns are of about the same length (time). Verify
wavelength decreases and frequency increases as engine RPM increases.
If conditions are not as specified, replace VAF sensor. If conditions
are as specified, go to step 4).
3) Warm vehicle to normal operating temperature. Ensure
headlights and accessories are off. Using scan tool, read VAF sensor
frequency value (item 12). See VOLUME AIRFLOW SENSOR VALUES table.
Frequency should increase when engine is raced. If values are not as
specified, replace VAF sensor. If values are as specified, turn
ignition switch to off position and disconnect VAF sensor connector.
Go to next step.
VOLUME AIRFLOW SENSOR VALUES TABLE









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Application Hz @ 700 RPM Hz @ 2500 RPM
Montero ................. 25-51 ................. 80-120
3000GT
DOHC
Non-Turbo ........... 24-50 ................. 71-111
Turbo ............... 26-52 ................. 93-133
SOHC .................. 21-47 .................. 57-97









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4) On 3000GT, go to next step. On Montero, disconnect MFI
relay connector. Using DVOM, check for continuity between VAF sensor
connector terminal No. 4 and MFI relay connector terminal No. 1. If
continuity does not exist, repair wiring harness as necessary. If
continuity exists, go to next step.
5) Using DVOM, check for continuity between chassis ground
and VAF sensor connector terminal No. 5. If continuity does not exist,
repair wiring harness as necessary. If continuity exists, go to next
step.
6) Ensure ignition switch is in OFF position. Disconnect PCM
connector. Ground PCM connector terminal No. 19. Using DVOM, check for
continuity between chassis ground and VAF sensor connector terminal
No. 7. If continuity does not exist, repair wiring harness as
necessary. If continuity exists, go to next step.
7) On 3000GT, go to next step. On Montero, ground PCM
connector terminal No. 61. Using DVOM, check for continuity between
chassis ground and VAF sensor connector terminal No. 3. If continuity
does not exist, repair wiring harness as necessary. If continuity
exists, turn ignition switch to ON position and go to step 9).
8) Turn ignition switch to ON position. Using DVOM, check
voltage between chassis ground and VAF sensor connector terminal No.
4. If battery voltage does not exist, repair wiring harness as
necessary. If battery voltage exists, go to next step.
9) Using DVOM, check voltage between chassis ground and VAF
sensor connector terminal No. 3. If voltage is not 4.8-5.2 volts,
replace PCM. If voltage is as specified, condition required to set DTC
is not present at this time. Go to next step.
10) Test is complete. Intermittent problem may exist. Road
test vehicle (if necessary) and attempt to duplicate conditions that
caused original complaint. Recheck for DTCs. If no DTCs are displayed,
go to INTERMITTENT DTCS .
DTC P0105: BAROMETRIC (BARO) PRESSURE SENSOR CIRCUIT FAILURE
NOTE: BARO pressure sensor is built into Volume Airflow (VAF)
sensor. For DTC P0105 test purposes, VAF sensor will be

continuity between chassis ground and EGR solenoid connector terminal
No. 2. If continuity does not exist, repair wiring harness as
necessary. If continuity exists, condition required to set DTC is not
present at this time. Go to next step.
12) Test is complete. Intermittent problem may exist. Road
test vehicle (if necessary) and attempt to duplicate conditions that
caused original complaint. Recheck for DTCs. If no DTCs are displayed,
go to INTERMITTENT DTCS .
DTC P0420, P0421 & P0431: CATALYST EFFICIENCY BELOW
THRESHOLD
NOTE: For terminal identification, see TERMINAL IDENTIFICATION. For
circuit and wire color identification, see
L - WIRING DIAGRAMS article.
Specific self-diagnostic test not available from manufacturer
at time of publication. Check catalytic converter and check for
cracked exhaust manifold. Also, see F - BASIC TESTING article.
DTC P0442: EVAPORATIVE (EVAP) EMISSION CONTROL SYSTEM LEAK
DETECTED
NOTE: For terminal identification, see TERMINAL IDENTIFICATION. For
circuit and wire color identification, see
L - WIRING DIAGRAMS article.
1) Remove fuel cap. Push fuel pipe restrictor to operate On-
board Fuel Vent Valve (OFLV). Install and tighten fuel cap. Remove
fuel cap and ensure distance between filler tube and OFLV is 1.1" (28
mm). If distance is as specified, go to next step. If distance is not
as specified, replace fuel tank filler tube assembly. Go to step 24).
2) Disconnect and plug air filter-to-EVAP vent solenoid hose
at air filter. Disconnect intake manifold plenum-to-EVAP purge
solenoid at intake manifold plenum. Install a "T" fitting between
vacuum hose and intake manifold plenum. Connect a hand-held
pressure/vacuum pump to "T" fitting. Go to next step.
CAUTION: DO NOT apply more than 0.57 psi in following step. Applying
more than specified psi can crack fuel tank.
NOTE: Ensure fuel tank is at least 1/4 full. The lower the fuel
level in fuel tank, the longer it takes to pressurize fuel
system.
3) Using scan tool, read Fuel Tank Differential Pressure
(FTDP) sensor (item 73). Using hand-held pressure/vacuum pump, apply\
0.42 psi. If scan tool reading reaches 0.42 psi, go to next step. If
reading does not reach 0.42 psi, go to step 9).
4) Wait 20 seconds and read scan tool. If scan tool reading
increases 0.06 psi or less, go to next step. If scan tool reading
increases more than 0.06 psi, go to step 21).
5) Disconnect EVAP canister purge hose. Connect Purge Flow
Indicator (MB995061) between EVAP canister and disconnected hose. Turn\
engine on and allow it to reach operating temperature. Turn all lights
and accessories off. Place transmission in Park or Neutral. Observe
purge flow indicator while increasing engine RPM several times. If
purge flow indicator reads less than 2.5 SCFH (20 cm(3)/sec), check
EVAP canister purge hose and EVAP canister port for clogging. If hose
and port are okay, check EVAP purge solenoid. See DTC P0443. If
solenoid is okay, replace EVAP canister. Go to step 24).
6) Using scan tool, read Engine Coolant Temperature (ECT)
sensor temperature (item 21). Compare scan tool reading with

system.
3) Using scan tool, read Fuel Tank Differential Pressure
(FTDP) sensor (item 73). Using hand-held pressure/vacuum pump, apply\
0.42 psi. If scan tool reading reaches 0.42 psi, go to next step. If
reading does not reach 0.42 psi, go to step 8).
4) Disconnect EVAP canister purge hose. Connect Purge Flow
Indicator (MB995061) between EVAP canister and disconnected hose. Turn\
engine on and allow it to reach operating temperature. Turn all lights
and accessories off. Place transmission in Park or Neutral. Observe
purge flow indicator while increasing engine RPM several times. If
purge flow indicator reads less than 2.5 SCFH (20 cm(3)/sec), check
EVAP canister purge hose and EVAP canister port for clogging. If hose
and port are okay, check EVAP purge solenoid. See DTC P0443. If
solenoid is okay, replace EVAP canister. Go to step 20).
5) Using scan tool, read Engine Coolant Temperature (ECT)
sensor temperature (item 21). Compare scan tool reading with
temperature gauge reading. If readings are about the same, go to next
step. If readings are not about the same, go to DTC P0115 test.
6) Using a thermometer, check engine compartment ambient
temperature. Using scan tool, read Intake Air Temperature (IAT) sensor\
temperature (item 13). Compare IAT sensor and thermometer readings. If\
readings are not about the same, go to DTC P0110 test. If readings are
about the same, go to next step.
7) Using scan tool, read Power Steering Pressure (PSP) switc\
h
status (item 27). Switch status should read ON when steering wheel is
turned. If switch status is as specified, go to step 20). If switch
status is not as specified, go to DTC P0551 test.
8) Remove fuel cap. Install a fuel tank filler tube adapter
in place of fuel cap. Plug fuel filler tube adapter hose. Disconnect
and plug air filter-to-EVAP vent solenoid hose at air filter.
Disconnect intake manifold plenum-to-EVAP purge solenoid at intake
manifold plenum. Install a "T" fitting between vacuum hose and intake
manifold plenum. Connect hand-held pressure/vacuum pump to "T"
fitting. Go to next step.
CAUTION: DO NOT apply more than 0.57 psi in following step. Applying
more than specified psi can crack fuel tank.
NOTE: Ensure fuel tank is at least 1/4 full. The lower the fuel
level in fuel tank, the longer it takes to pressurize fuel
system.
9) Using scan tool, read Fuel Tank Differential Pressure
(FTDP) sensor (item 73). Using hand-held pressure/vacuum pump, apply\
0.42 psi. If scan tool reading reaches 0.42 psi, replace fuel cap. Go
to step 20). If reading does not reach 0.42 psi, go to next step.
10) Disconnect hand-held pressure/vacuum pump from "T"
fitting. Install an evaporative emission system tester in place of
vacuum held pump and apply 0.49 psi. Wait two minutes. If pressure
drops less than 0.20 psi, go to next step. If pressure drops 0.29 psi
or more, go to step 13).
11) Disconnect EVAP purge solenoid-to-EVAP canister hose at
EVAP canister. Connect hand-held pressure/vacuum pump to hose and
apply 0.9 psi. If pressure is not maintained, check EVAP purge
solenoid for leak. If EVAP purge solenoid is okay, replace hose. Go to
step 24). If pressure is maintained, go to next step.
12) Disconnect EVAP vent solenoid-to-EVAP canister hose at
EVAP canister. Connect hand-held pressure/vacuum pump to hose and
apply 0.9 psi. If pressure is not maintained, check EVAP vent solenoid
for leak. If EVAP vent solenoid is okay, replace hose. Go to step 20).
If pressure is maintained, replace EVAP canister. Go to step 24).
13) Ensure hoses are properly routed and connected. See M -