check engine light MITSUBISHI 3000GT 1991 Service Manual

GENERAL - Precautions before Service0045
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PRECAUTIONS BEFORE SERWCEMOOOAAOSERVICING ELECTRICAL SYSTEM
1. Note the following before proceeding with work on the
electrical system.
Note that the following must never be done:
Unauthorized modifications of any electrical device or
wiring, because such modifications might lead to a vehicle
malfunction, over-capacity or short-circuit that could result
in a fire in the vehicle.
2. When servicing the electrical system, disconnect the
negative cable terminal from the battery.
Caution1. Before connecting or disconnecting the negative
cable, be sure to turn off the ignition switch and the
lighting switch.(If this is not done, there is the possibility of
semiconductor parts being damaged.)
2. After completion of the work steps [when the
battery’s negative (-) terminal is connected], warm
up the engine and allow it to idle for approximately
five minutes under the conditions described below,in order to stabilize the engine control conditions,
and then check to be sure that the idling is
satisfactory.
Engine coolant temperature: 80 - 95°C (176 - 203°F)
Lights, electric fans, accessories: OFF
Transaxle: neutral position(A/T models: “N” or “P”)
Steering wheel: neutral (center) position
VEHICLE WASHING
If high-pressure car-washing equipment or steam car-washing
equipment is used to wash the vehicle, be sure to maintain the
spray nozzle at a distance of at least 300 mm (12 in.) from any
plastic parts and all opening parts (doors, luggage compart-
ment, etc.).
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ENGINE - Service Adiustment ProceduresII-13
I_ ianltion tlminaI!H Connector for Igdpstment 6rown)
4tll II -7FUO9371IGNITION TIMING ADJUSTMENTMllFLAF
(1) The vehicle should be prepared as follows before the
inspection and adjustment.
lEngine coolant temperature: 80 - 95°C (176 - 205°F)
l Lights, electric cooling fan and accessories: OFF
l Transaxle: neutral
(P for A/T)l Steering wheel: neutral position
(2) Insert a paper clip to the connector, and connect a
tachometer to the paper clip.
NOTEDo not use the Multi-use tester.
If tested with the Multi-use tester connected to the
diagnosis connector, the ignition timing will not be the basic
timing but be ordinary timing.
(3) Set the timing light.
(4) Start the engine and run at idle.
(5) Check curb idle speed.
Curb idle speed: 700
f 100 rpm
NOTEThe engine speed indicated is a third of actual speed. In
other words, the reading of the tachometer times 3 is actual
speed.
(6) Turn OFF the ignition switch.
(7) Using a jumper wire, ground the ignition timing adjusting
terminal.
NOTEGrounding this terminal sets the engine to the basic ignition
timing.
\(8) Start the engine and run at idle.
(9) Check basic ignition timing.
Basic ignition timing: 5” BTDC
k 2”
(10)lf not within the standard value range, loosen the crank
angle sensor mounting nut and adjust by turning the crank
angle sensor. Turning it to the counterclockwise retards
timing, and to the clockwise advances it.
(1 l)After adjustment, tighten mounting nut taking care not to
move the crank angle sensor.
(12)Turn OFF the ignition switch.
(13)Disconnect the jumper wire connected at step (7).
(14)Start and run the engine at curb idle speed.
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11-14ENGINE - Service Adjustment Procedures
(15)Check to be sure that the idling ignition timing is the correct
timing.
Actual ignition timing: Approx. 15” BTDC
NOTE:d
(1) Ignition timing is variable even under normal operation.
(2) And it is automatically advanced at higher altitudes.
CURB IDLE SPEED INSPECTIONMllFMAB
(1) The vehicle should be prepared as follows before the
inspection.
lEngine coolant temperature: 80 - 95°C (176 - 205°F)
l 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-1 3.)
(3) Set a timing light.
(4) Using a jumper wire, ground the ignition timing adjusting
terminal.
(5) Start the engine and let it idle.
(6) Check whether or not the ignition timing is the standard
value; if not, adjust.
Standard value: 5” BTDC + 2”
NOTECheck the ignition timing with the Multi-use tester not
connected to the diagnosis connector.
(7) Remove the jumper wire from the ignition timing adjusting
terminal.
(8) When using the Multi-use tester, turn OFF the ignition
switch and connect the tester to the diagnosis connector.
(9) Idle the engine for two minutes.
(10)Check the idle speed.
Curb idle speed:
700 + 100 rpm
NOTE(1) The idling speed is automatically regulated by the
idle-speed control system.
(2)’ The engine speed indicated is a third of actual speed. In
other words, the reading of the tachometer times 3 is
actual speed.
(1l)lf not within the standard value range, refer to GROUP 13 -Service Adjustment Procedures.
d
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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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11-32ENGINE - Rocker Arm and Camshaft
r
I
/7EN024E
Small wire
8ENOO58
Identification mark(stamped on hexagon section)
7EN0249
Front sideINSPECTION
MllZCAB
CAMSHAFTMeasure cam height (longer diameter of the cam). If it exceeds
the limit, replace the camshaft.
Standard value:
Intake side
35.49 mm (1.3972 in.)
Exhaust side
35.20 mm (1.3858 in.)
Limit:
Intake side
34.99 mm (1.3776 in.)
Exhaust side
34.70 mm (1.3661 in.)SERVICE POINTS OF INSTALLATION
MllZDAK
11. INSTALLATION OF LASH ADJUSTER
(1) Immerse the lash adjuster in clean diesel fuel.
(2) Using a small wire, move the plunger up and down 4 or
5 times while pushing down lightly in the check ball in
order to bleed out the air.
(3) Install the lash adjuster to the cylinder head.
9. INSTALLATION OF CAMSHAFT
(1) Turn the crankshaft to bring No.1 cylinder to the top
dead center.
(2) Check that the rocker arm is installed correctly on the
lash adjuster and valve.
(3) Install the camshaft noting the identification mark
(stamped on the hexagon sectioned).
Identification mark: Intake sideV
Exhaust side C
(4) Install the camshafts with their dowel pins positioned
as shown in the illustration.
Rear side ,
Approx. 100”
Pl
Frontm&k
M
0
/
Cap No
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Identificationmark
7EN03168. 7. 6. 4. 2. INSTALLATION OF BEARING CAPS
(1) Install noting the identification mark and cap No. No.2, 3
and 4 bearing caps bear the front mark. Install these
caps with the mark lined up with the front mark on the
cylinder head.
Identification mark: Intake side
IExhaust side E

11-36ENGINE - Cylinder Head and Valve
SquarenssVALVE SPRINGS
(1) Check free length of each valve spring and replace if
necessary.
!
FreelengthStandard value: 46.9 mm
(1.846 in.)\bJLimit: 45.9 mm
(1.807 in.)
(2) Using a square, test squareness of each valve spring. If
spring is excessively out of square, replace it.
Standard value: Less than 2”
Limit: 4
1 EN035
VALVE GUIDES
1 EN29ECheck the valve stem-to-guide clearance. If the clearance
exceeds the service limit, replace the valve guide with new
oversize part.
Standard value:
Intake
Exhaust0.02 - 0.05 mm (0008 - .0020 in.)
Limit:0.05
- 0.09 mm (.0020 - .0035 in.)
Intake
Exhaust0.10 mm (0039 in.)
0.12 mm (0047
in.)6EN043
1AVALVE SEAT RECONDITIONING PROCEDURES
(I 1 Before valve seat reconditioning, check valve stem to guide
clearance.
(2)Recondition the valve seat with a seat grinder or cutter. The
valve seat width should be the specified value at the center
of the valve face.
Inspect the valve seat with prussian blue to determine
LJwhere the valve contacts the seat. To do this, coat valve
seat lightly with prussian blue, and then set valve in place.
Rotate the valve with light pressure. If the blue is
transferred to the center of valve face, contact is satisfac-
tory.
If the blue is transferred to top edge of the valve face, lower
valve seat with a 30 degrees stone or cutter. If the blue is
transferred to the bottom edge of valve face, raise valve
seat with a 65 degrees stone or cutter.
Valve seat diameter:
Intake34 mm (I .34 in.)
ExhaustSeat width: 0.9
29.5 mm (1.16 in.)
- 1.3 mm (035 - .051 in.)
(3) The valve and valve seat should be lapped with a lapping
compound.
VALVE SEAT REPLACEMENT PROCEDURE
(1) Grind the valve seat to be replaced from the inside to thin
the wall thickness. Then, remove the valve seat.
1 ENOE18
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FUEL
SYSTEM
CONTENTSM13AA- _
CRUISE CONTROL SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . .158SPECIFICATIONS. . . . . . . .._._....................................................155
CRUISE CONTROL SYSTEM*................................................185
SERVICE ADJUSTMENT PROCEDURES............................178
Cruise Control Cables Inspection and Adjustment........178Cruise Control SystemInspection....................................179individual Parts Inspection....................................................181
SPECIAL TOOLS........................................................................159
SPECIFICATIONS....................................................................158
General Specifications........................................................158Service Specifications........................................................158
TROUBLESHOOTING............................................................159
Check Chart............................................................................163Harness and Components Layout....................................176Preliminary Inspection........................................................159Self-diagnosis Checking........................................................172Troubleshooting Quick Reference Chart............................159
ENGINE CONTROL............................................155
ENGINE CONTROL................................................................157
SERVICE ADJUSTMENT PROCEDURES............................156
Accelerator Cable Inspection and Adjustment................156Accelerator Switch Inspection and Adjustment................156
Service Specifications........................................................
155
TROUBLESHOOTING............................................................
155
Accelerator Cable and Accelerator Pedal........................155
FUEL SYSTEM....................................................3
DETONATION SENSOR........................................................154
FUEL FILTER............................................................................
153
FUEL LINE AND VAPOR LINE................................................151
FUEL PUMP AND FUEL GAUGE UNIT ASSEMBLYAND OVERFILL LIMITER (TWO-WAY VALVE)................149
FUEL TANK.................................................................................146
GENERAL INFORMATION
....................................................
3
MPI System Diagram............................................................3
INJECTOR................................................................................141
ON-VEHICLE INSPECTION OF MPI COMPONENTS........36
Active Exhaust Control Unit ............................130Air Conditioner Switch and Power Relay............................82Air Flow Sensor....................................................................54Anti-lock Brake Signal ........................................133Barometric Pressure Sensor................................................60CONTINUED ON NEXT PAGE
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
(1)A Supplemental Restraint System (SRS), which uses a driver-side air bag, has been installed in the 3000GT.(2)The SRS includes the following components: impact sensors, SRS diagnosis unit: SRS warning light, air bagmodule, clock spring, interconnecting wiring. Other SRS-related components (that may have to be
removed/installed in connection with SRS service or maintenance) are indicated in the table of contents byan asterisk (*).
WARNING!(I)Improper service or maintenance of any component of the SRS, or any SRS-related component, can lead to
personal injury or death to service personnel (from inadvertent firing of the air bag) or to the driver (from
rendering the SRS inoperative).
(2) Service or maintenance of any SRS component or SRS-related component must be performed only at anauthorized MITSUBISHI dealer.
(3) MITSUBISHI dealer personnel must thoroughly review this manual, and especially its GROUP
528 -Supplemental Restraint System (SRS), before beginning any service or maintenance of any component of theSRS or any SRS-related component.

13-2
Boost Meter ........................................................128Components Inspection Procedure....................................40
Components Location........................................................36
Crank Angle Sensor
............................................................72Detonation Sensor................................................................84EGR Control Solenoid Valve
........................................121
EGR Temperature Sensor ............................92ElectricalLoad Switch........................................................86Engine and Transaxle Total Control Signal ............135Engine Control Unit Power Ground....................................44Engine Coolant Temperature Sensor................................62Fuel Pressure Control Valve ............................123Fuel Pressure Test................................................................138Fuel Pump ....................................................45Fuel Pump ............................................................48
Fuel Pump Operation Check................................................137Fuel Pump Relay No. 2........................................................53Fuel Pump Resistor............................................................53
Idle Position Switch............................................................68Idle Speed Control Servo (Stepper Motor Type)............1 IOIgnition Coil and Power Transistor....................................115Ignition Switch-ST and Inhibitor Switch ................76Ignition Switch-ST ................................................75Induction Control Valve Position Sensor
........................................................................90
Injectors........................................................101Injectors................................................................105Intake Air Temperature Sensor............................................57Muffler Mode Changeover Switch ....................88Oxygen Sensor ............................................
94
Oxygen Sensor ....................................................98
Power Steering Oil Pressure Switch................................80Power Supply and Ignition Switch-IG................................41
Purge Control Solenord Valve............................................1 19Release of Residual Pressure from High
Pressure Fuel Hose............................................................137Throttle Position Sensor....................................................65Top Dead Center Sensor....................................................70Variable Induction Control Servo (DC Motor)
........................................................................131Vehicle Speed Sensor........................................................78Waste Gate Control Solenoid Valve ................126
SERVICE ADJUSTMENT PROCEDURES............................31
Adjustment of Fixed SAS....................................................35Adjustment of Idle Position Switch and
Throttle Position Sensor (TPS)............................................33Basic Idle Speed Adjustment............................................31Throttle Body (Throttle Valve Area) Cleaning....................33
SPECIAL TOOLS........................................................................8
SPECIFICATIONS
....................................................................6
General Specifications........................................................6Sealant....................................................................................7Service Specifications........................................................7
THROlTLE BODY....................................................................143
TROUBLESHOOTING............................................................9
Check Chart Classified by Problem Symptoms................16Circuit Diagram....................................................................18Engine Warning Light (Malfunction Indicator Light)........11Explanation and Cautions about Harness Check............10Explanation of Troubleshooting Procedures....................9Fuel Tank and Fuel Line........................................................30
Problem Symptoms Table (For Your Information)............17Self-diagnosis........................................................................12)
I

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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13-12FUEL SYSTEM - Troubleshooting
MALFUNCTION INDICATOR LIGHT INSPECTION
(1) Check that when the ignition switch is turned on, the lightilluminates for about 5 seconds and then goes out.
(2) If the light does not illuminate, check for open circuit in
dharness, blown fuse and blown bulb.
SELF-DIAGNOSIS
The engine control unit monitors the input/output signals (some
signals at all times and the others under specified conditions) ofthe engine control unit.
When it is noticed that an irregularity has continued for a
specified time or longer from when the irregular signal is
initially monitored, passing a certain number, the engine controlunit judges that an irregularity has occurred, memorizes the
malfunction code, and outputs the signal to the self-diagnosis
output terminal.
There are 21 diagnosis items, including the normal state, andthe diagnosis results can be read out with a voltmeter or
multi-use tester.Moreover, since memorization of the malfunction codes is
backed up directly by the battery, the diagnosis results are
memorized even if the ignition key is turned off. The malfunc-
tion codes will, however, be erased when the battery terminalor the engine control unit connector is disconnected.
The malfunction code can also be erased by turning on the
ignition switch and sending the malfunction code erase signalfrom the multi-use tester to the engine control unit.
CautionIf the sensor connector is disconnected with the ignition
_ _switch turned on, the malfunction code is memorized. Ind
this case, send the malfunction code erase signal from themulti-use tester to the engine control unit or disconnect
the battery terminal
(-) for 10 seconds or more, and the
diagnosis memory will be erased.
The 21 diagnosis items are provided as follows, and if plural
items are activated, they are all indicated sequentially from the
smallest code number.
CautionThe malfunction code for the ignition timing adjustment
signal is output when the line of the ignition timing
adjustment terminal is shorted to ground. Therefore, the
malfunction code is also output when the ignition timing
adjustment terminal is grounded to adjust the ignition
timing, but this does not show any abnormality.
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