1991 MITSUBISHI 3000GT low oil pressure

GENERAL - Master Troubleshootina00-27HARD STEERING
L
L
Symptom
Hard steeringProbable causeLoose power steering oil pump belt
Reference page or remedy37A-8
1POOR RETURN OF STEERING WHEEL TO CENTER
Symptom
Poor return of steering wheelto center
Probable cause
Improper front wheel alignment
Improper tire pressure
Excessive tightened rack support cover
Damaged front wheel bearing
Reference page33A-4
31-3
37A-1926-10
Low fluid levelReplenish
Air in power steering system37A-10
Low tire pressure
313
Excessive turning resistance of lower arm ball33A-9joint
Excessively tightened steering gear box
rack support cover
37A-19
Improper front wheel alignment
Excessive turning resistance of tie-rod ball
joint
Sticky flow control valve
Bent rack in steering gear box33A-437A-6
37A-30
37A-19
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GENERAL - Master Troubleshootinn
VEHICLE PULLS TO ONE SIDE
Symptom
Vehicle pulls to one sideProbable cause
Improper front or rear wheel alignmentReference page or remedy33A-4
34-5,23
lmbalanced or worn tires
Uneven tire pressure31-3
Excessive turningresistance of lower arm ball33A-9
I--_Wheel beanng serzureReplace
I---Broken or worn coil spring33A-5Ir
~~~~~~Bent front or rear axle drive shaft126-11I
I-Deformed lower arm1 33A-8I
Improper tire pressure31-3
lmbalanced wheelsReplace
Poor turning resistance of lower arm ball joint33A-9
Excessive play of steering wheel37A-5
Broken or weak front stabilizer33A-10
Worn lower arm bushing33A-8
Malfunctioning shock absorber33A-5
34-l 3,33
Broken or weak coil spring
Wear, play, or seizure of wheel bearing
Wear, play, or seizure of drive shaft ball jointReplace
26-l 127-l 8 STEERING WHEEL SHIMMY
SymptomProbable cause
Steering wheel shimmyImproper front or rear wheel alignmentReference page or remedy33A-434-5,23
Boll-OMING
Symptom
BottomingProbable cause
Overloaded vehicleReference page or remedy
Correct
Broken or weak coil spring33A-5
34-l 3.33
IMalfunctioning shock absorber
1 TSB Revision

GENERAL - Maintenance Service00-39ogPOO268. ENGINE OIL FILTER (Change)
MOOEAEJThe quality of replacement filters varies considerably. Only high
quality filters should be used to assure most efficient service.
Genuine oil filters require that the filter be capable of
withstanding a pressure of 256 psi are high quality filters and
are recommended as follows:
Oil Filter Part No.
MITSUBISHI Genuine Parts: MD136790
ENGINE OIL FILTER SELECTIONThis vehicle is equipped with a full-flow, throw-away oil filter.
The same type of replacement filter is recommended as a
replacement filter for this vehicle. It is possible, particularly in
cold weather, that this vehicle may develop high oil pressure
for a short duration. You should be sure that any replacement
filter used on this vehicle is a high-quality filter and is capable of
withstanding a pressure of 256 psi (1,765
kpa) (manufacturer’s
specifications) to avoid filter and engine damage. The following
is a highquality filter and is strongly recommended for use on
this vehicle: Mitsubishi Engine Oil Filter P/N MD136790.
Any replacement oil filter should be installed in accordance with
the oil filter manufacturer’s installation instructions.
(1) Remove the engine oil filter by using the oil filter wrench.
(2) Clean the oil filter mounting surface of the oil filter bracket.
(3) Coat engine oil to the O-ring of new oil filter.
(4) Turn the oil filter by hand and install to the filter bracket.
NOTEThe oil filter tightening torque is 14 Nm (11
ft.lbs.1.(5) Start and run engine and check for engine oil leaks.
(6) After stopping engine, check oil level and refill as neces-
sary.
9. MANUAL TRANSAXLE (Inspect oil level)
MOOSBCGInspect each component for evidence of leakage, and check
the oil level by remaining the filler plug. If the oil is contami-
nated, it is necessary to replace it with new oil.
(1) With the vehicle parked at a level place, remove the filler
plug.
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00-40
GENERAL - Maintenance Service
(2) Check that the transaxle oil level is at the lower portion of
the filler plug hole. For AWD-vehicles, check that the
transfer oil level is at the portion shown in the illustration.
(3) Check to be sure that the transmission oil is not noticeably
‘ddirty, and that it has a suitable viscosity.
10. AUTOMATIC TRANSAXLE
(Inspect fluid level)
MOOSEDL
1.Drive until the fluid temperature reaches the usual tempera-
ture
[70 - 80°C (160 - 18O”F)I.2. Place vehicle on level floor.
3. Move selector lever sequentially to every position to fill
torque converter and hydraulic circuit with fluid, then place
lever in “N” Neutral position. This operation is necessary to
be sure that fluid level check is accurate.
4. Before removing dipstick, wipe all dirt from area around
dipstick. Then take out the dipstick and check the condition
of the fluid.
The transaxle should be overhauled under the following
conditions.
l If there is a “burning” odor.
l If the fluid color has become noticeably blacker.
lIf there is a noticeably great amount of metal particles in
the fluid.
5. Check to see if fluid level is in “HOT” range on dipstick. If
fluid level is low, add ATF until level reaches “HOT” range.
Low fluid level can cause a variety of conditions because it
allows pump to take in air along with fluid. Air trapped in
hydraulic circuit forms bubbles which make fluid spongy.
Therefore, pressures will be erratic.
Improper filling can also raise fluid level too high. When
transaxle has too much fluid, gears churn up foam and
cause same conditions which occur with low fluid level,
resulting in accelerated deterioration of ATF transmission
fluid.
In either case, air bubbles can cause overheating, fluid
oxidation, which can interfere with normal valve, clutch, and
servo operation. Foaming can also result in fluid escaping
from transaxle vent where it may be mistaken for a leak.
6. Be sure to examine fluid on dipstick closely.
L/(Change fluid)
Drain the fluid and check whether there is any evidence of
contamination.
Replenish with new fluid after the cause of any contamination
has been corrected.
(1) Remove drain plug at transaxle case bottom to let fluid
drain.(2) Place a drain container with large opening under the
transaxle oil pan.
(3) Loosen oil pan bolts and tap pan at one corner to break it
loose allowing fluid to drain, then remove oil pan.
d
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II-IOENGINE - Troubleshooting
TROUBLESHOOTINGmiwm
SymptomProbable cause
RemedyI,aJ
Compression too low) Cylinder head gasket blown1 Replace gasketI
Piston ring worn or damage
Piston or cylinder worn
Replace rings
Repair or replace piston and/or cylinder
block
Valve seat worn or damage
Repair or replace valve and/or seat ring
3il pressure drop
Engine oil level too lowCheck engine oil level
Oil pressure switch faulty
Oil filter clogged
Replace oil pressure switch
Install new filter
Oil pump gears or cover worn
Thin or diluted engine oilReplace gears and/or cover
Change engine oil to correct viscosity
1 Oil relief valve stuck (opened)) Repair relief valve
Excessive bearing clearance
Replace bearingsIbOil relief valve stuck (closed)
Incorrect lash adjusterRepair relief valve
Replace lash adjuster Oil pressure too high
Noisy valves
Thin or diluted engine oil (low oil pressure)Change engine oil
Valve stem or valve guide worn or damageReplace valve and/or guide
Connecting rod noise/
nain bearing noiseInsufficient oil supplyCheck engine oil level
Thin or diluted engine oilChange engine oil
Excessive bearing clearanceReplace bearings
Timing belt noise
Incorrect belt tensionAdjust belt tension
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11-16ENGINE - Service Adjustment Procedures
MANIFOLD VACUUM INSPECTION
MllFNAR
(1) The vehicle should be repaired as follows before the
inspection.
lEngine coolant temperature: 80 - 95°C (176 - 205°F)‘dl Lights, electric cooling fan, and accessories: OFF
l Transaxle: Neutral
(P for A/T)l Steering wheel: neutral position
(2) Connect a tachometer. (Refer to P.l l-l 3.)
(3) Disconnect the vacuum hose from the nipple for taking off
fuel pressure regulator vacuum from the air intake plenum.
(4) Conncet a three-way joint between the removed vacuum
hose and the nipple and connect a vacuum gauge to the
joint.
(5) Start the engine and check that idle speed is within the
standard value range.
(6) Check the manifold vacuum.
Standard value:
*
Approx. 520 mmHg (20 in.Hg)
Approx. 495 mmHg (19 in.Hg)LASH ADJUSTERS CHECK
Ml 1 FEAFIf an abnormal noise is heard from the lash adjusters, check as
follows.
(1) After warming up the engine, stop it.
(2) While installed to the cylinder head, press the part where
the rocker arm contacts the lash adjuster at the very top. If
the adjuster is normal, the part pressed will feel very hard.
d
(3) If it easily moves all the way downward when pressed,
there is a malfunction of the lash adjuster and it should be
replaced with a new one.
(4) If it feels spongy or elastic, probably oil with air mixed in it
has entered the lash adjuster. Check whether the amount
of oil is too much or is not enough and the cause of air
becoming mixed into the oil is a damaged oil screen or oil
screen gasket.
(5) After repairing the cause of the air leak, warm up the engine
and then drive the vehicle at low speed for a while. Stop the
engine and leave it off for a few minutes; then restart the
engine and drive at low speed. Repeat this procedure
several times during the course of about one hour so as to
remove the air from the oil.
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FUEL SYSTEM - Troubleshooting13-11
L
L
Sensor side6FU1215
Malfunctionl
If the sensor impressed voltage is abnormal, check the wire
for an open circuit or short-circuit to ground and repair as
necessary. If the wire is normal, replace the engine control
unit and check again.l To check the voltage, use a digital voltmeter (or circuit
tester) as a rule.
[However, use an analog voltmeter for checking the power
transistor drive voltage.]ENGINE WARNING LIGHT (MALFUNCTION IN-
DICATOR LIGHT)
Among the self-diagnosis items, a malfunction indicator lightcomes on to notify the driver of the emission control items
when an irregurality is detected.
However, when an irregular signal returns to normal and theengine control unit judges that it has returned to normal, the
malfunction indicator light goes out.
Moreover, when the ignition switch is turned off, the light goes
out. Even if the ignition switch is turned on again, the light doesnot come on until the irregularity is detected.
Here, immediately after the ignition switch is turned on, the
malfunction indicator light is lit for 5 seconds to indicate that
the malfunction indicator light operates normally.
ITEMS INDICATED BY THE MALFUNCTION INDICATOR
LIGHT
Engine control unit
Oxygen sensor
Air flow sensor
Intake air temperature sensor
Throttle position sensor
Engine coolant temperature sensor
Crank angle sensor
Top dead center sensor
Barometric pressure sensor
Detonation sensor
Ignition timing adjustment signal
Injector
EGR system
Ignition coil, power transistor unit
Caution
The malfunction indicator light comes on when the line ofthe ignition timing adjustment terminal is shorted to
ground. Therefore, the light also comes on when the
ignition timing adjustment terminal is grounded to adjust
the ignition timing, but this does not show any abnormal-
ity.
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FUEL SYSTEM - 0
n-vehicle Inspection of MPI Components
AIR FLOW SENSORAir flow sensor J
III I
\I\Y7FUO941
@ Equipment side
connector
Air flow rate (liters/second)
@ Harness side
connector
I
Control relay
I
Air flow sensor
ECU
’ 7FUO654
Engine control
unit connector
7FUO653
OPERATIONl
The air flow sensor located in the air cleaner converts the engine intake air volume into a pulse signal of
frequency proportional to the air volume and inputs it to the engine control unit, which then computes thefuel injection rate, etc. based on the input signal.
l
The air flow sensor power is supplied from the control relay to the air flow sensor and is grounded in theengine control unit. The air flow sensor generates a pulse signal as it repeatedly opens and closes
between the 5 V voltage supplied from the engine control unit and ground.
TROUBLESHOOTING HINTS
Hint 1 :If the engine stalls occasionally, crank the engine and shake the air flow sensor harness. If the engineHint 2:stalls, poor contact of the air flow sensor connector is suspected.
If the air flow sensor output frequency is other than 0 when the ignition switch is turned on (but notHint 3:starting the engine), faulty air flow sensor or engine control unit is suspected.
If the engine can be run idle even though the air flow sensor output frequency is out of specification,troubles are often found in other than the air flow sensor itself.
[Examples](1) Disturbed air flow in the air flow sensor
(Disconnected air duct, clogged air cleaner element)
(2) Poor combustion in the cylinder
(Faulty ignition plug, ignition coil, injector, incorrect compression pressure, etc.)
(3) Air leaking into the intake manifold through gap of gasket, etc.
(4) Loose EGR valve seatTSB Revision