1991 MITSUBISHI 3000GT sensor

13-102FUEL SYSTEM - On-vehicle Inspection of MPI Components
TROUBLESHOOTING HINTSHint 1: If the engine is hard to start when hot, check fuel pressure and check the injector for leaks.
Hint 2:If the injector does not when the engine that is hard to start is cranked, the following as well as the
Iinjector itself may be responsible.
(1) Faulty power supply circuit to the engine control unit, faulty ground circuit
\-J
-(2) Faulty control relay
Hint 3:(3) Faulty crank angle sensor, top dead center sensor
If there is any cylinder whose idle state remains unchanged when the fuel injection of injectors is cut
one after another during idling, make following checks about such cylinder.
(1) Injector and harness check
(2) Ignition plug and high tension cable check
(3) Compression pressure check
Hint 4: If the injector harness and individual part checks have resulted normal but the injector drive time is
out of specification, the following troubles are suspected.
(1)Poor combustion in the cylinder (faulty ignition plug, ignition coil, compression pressure, etc.)
(2) Loose EGR valve seating
(3) High engine resistance
INSPECTIONUsing Multi-use Tester
FunctionItem No. Data displayCheck conditionCoolant temperatureStandard valueData reading 41
Drive time”’Engine: Cranking0°C (32”F)*zApprox. 17 ms
20°C (68°F)Approx. 46 ms
8O"C(176"F)Approx. 11 ms
Function
Data readingItem No.Data display
41Drive time*3l Engine coolant tem-perature: 80 to 95°C700 rpm (Idle)2.4-3.0 ms
(176 to 205°F)2,000 rpm2.0-2.6
msl Lamps, electric coolingfan, accessory units:When sharp racing isTo increaseAll OFF
madel Transaxle: Neutral
(P range for vehicle
with A/T)l Steering wheel: Neutral
Check conditionEngine stateStandard value ,
.---NOTE“I : The injector drive time refers to when the supply voltage is 11 V and the cranking speed is less than 250 rpm.*2: When coolant temperature is lower than 0°C (32°F). injection ismade by four-cylinders.---simultaneously.
“3: When the vehicle is new [within initial operation of about 500 km (300 miles)], the injector drive time may be about
10% longer.
Function
Actuator testItem No.
Drive content
Check conditionNormal state
01No. 1 injector shut offEngine: Idling afterIdle state to change
02No. 2 injector shut offwarm-up
(Shut off the injectorsfurther (becoming less
in sequence during afterstable or stalling)
03
No. 3 injector shut offengine warm-up, check
04No. 4 injector shut offthe idling condition)
05No. 5 injector shut off
06No. 6 injector shut off
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FUEL SYSTEM - On-vehicle lnwection of MPI ComDonents13-131
iVARIABLE INDUCTION CONTROL SERVO (DC MOTOR) Variable induction control servo
Y(DC motor)(with built-in induction/-control valve oosition sensor)-7Fllfl807Engine control unit
Close
connector
,\ IOpen@ Equipmentside1,,I2DC motorVariable
induction
control
servo
1 FU0646
Engine control unit connector
7FUO653
OPERATION
lAs the DC motor is driven clockwise or counterclockwise by the signal from the engine control unit, the
variable induction valve opens or closes.
lThe DC motor is driven clockwise or counterclockwise as the direction of current flow is changed by the
motor drive
IC in the engine control unit.
INSPECTIONUsing Multi-use tester
Function
Actuator testItem No.Drive content
Check conditionNormal state
11Drive the variable induc-Ignition switch: ONTurn the variable inductiontion control (MC) servovalve shaft (Variable induc-
(Open and close the
vari-tion valve: FULL CLOSEable induction valve)+ FULL OPEN
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13-144FUEL SYSTEM - Throttle- Body
DISASSEMBLY AND REASSEMBLY
2.0
Nni1.4ft.lbs.
/
Disassembly steps
1. Dash pot2. Hose
3. Vacuum valve
>

l *4. Throttle position sensor
(within idle position switch)
5.
Idle speed control servo
assembly
6. Throttle body
7FU1023
\7FU1057 1SERVICE POINT OF DISASSEMBLY
MlBSFAN
Caution
1.When loosening a Phillips screw which has been firmly
tightened, use a Phillips screwdriver that is an exact fitfor the screw.
2. Do not remove the throttle valve.
3.Be careful when removing the throttle position sensorand idle speed control servo mounting screws, as
adhesive has been applied these screws.
INSPECTION
Ml3SHAt.lDASH POT INSPECTION
(1) Check the dash pot diaphragm for damage. First, push up
the rod fully and closing tightly the nipple with a finger,
release the rod. The diaphragm is intact if the rod does not
return to the initial position while the nipple is held closed
with a finger. If the rod returns, the diaphragm is broken.
Replace the dash pot.
VACUUM VALVE INSPECTION
(1) Remove the filter from the vacuum valve.
(2) Connect a hand vacuum pump to the black nipple of the
vacuum valve.
(3) With the other nipple closed by the finger, apply a negative
pressure of 500 mmHg (19.7 in.Hg.) to make sure that the
negative pressure is maintained.
(4)Let go your finger and make sure that the negative pressure
leaks out gradually.
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FUEL SYSTEM - Throttle Body13-145Orifice
Nipple (green)3EM05iGroundThrottle
positlonsensor output
Idle-position
switchTh>ottle position
sensor power7FUO535(5) Disconnect the hand vacuum pump and connect it to the
other nipple.
(6)Make sure that the negative pressure leaks out as soon as it
is applied.
CLEANING THROTTLE BODY PARTS
(1) Clean all throttle body parts.
Do not use solvent to clean the following parts:
l Throttle position sensor (Idle position switch)
l Idle speed control servo
If these parts are immersed in solvent, their insulation will
deteriorate.
Wipe them with cloth only.
(2) Check if the vacuum
pot-t or passage is clogged. usecompressed air to clean the vacuum passage.
SERVICE POINT OF REASSEMBLY
M13SGAN4. INSTALLATION OF THROTTLE POSITION SENSOR
(1) Set the throttle position sensor to the throttle body as
shown in the diagram.
(2) After turning the throttle position sensor 90” in the
clockwise direction to set it, tighten by turning the
screw.
(3) Connect the circuit tester between 1 (ground) and 3
(output), or between 3 (output) and 4 (power). Then,
make sure that the resistance changes smoothly when
the throttle valve is slowly moved to the fully open
position.
(4) Check for continuity across terminals 2 (Idle position
switch) and 1 (ground) with the throttle valve both fully
closed and fully open.
IThrottle valve positionIContinuityI
Fully closedConductive
Fully openINon-conductiveIIf there is not continuity with the throttle valve fully
closed, turn the counterclockwise direction, and then
check again.
(5) If the above specifications are not met, replace the idle
position switch.
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13-154FUEL SYSTEM - Detonation Sensor
DETONATION SENSORREMOVAL AND INSTALLATION
Pre-removal and Post-installation Operation
l Release and Installation of the Air Intake Plenum
(Refer to GROUP
15-Air Intake Plenum.)
l Removal and Installation of the Intake Manifold
(Refer to GROUP 15
- Intake Manifold.)
l * +*I. Detonation sensor
20-25NmSERVICE POINT OF REMOVAL
1. REMOVAL OF DETONATION SENSOR
SERVICE POINT OF INSTALLATION
1. INSTALLATION OF DETONATION SENSOR
When the detonation sensor is installed, be sure to tighten
Idit precisely to the specified torque as its installation affects
the engine control.
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CRUISE CONTROL SYSTEM - Troubleshootina13461
Trouble symptom
l The set vehicle speed variesgreatly upward or downward.l “Hunching” (repeated alter-
nating acceleration and
deceleration) occurs after
setting is made.
Probable cause
Check chart No.Remedy
Malfunction of the vehicleNo. 4Repair the vehicle speedspeed sensor circuit
sensor system, or replacethe part.Malfunction of thespeedometer cable orspeedometer drive gear
Vacuum pump assembly
No. 5Repair the actuatorcircuit poor contact
system, or replace thepart.Malfunction of thevacuum pump assembly
(including air leaks from
negative pressure
passage)
The cruise control system is notcanceled when the brake pedal
is depressed.Malfunction of the ECU
-Replace the ECU.
Brake switch (for cruiseNo. 6Repair the harness or
control) malfunction
replace the stop light
(short-circuit)switch.
Vacuum pump assemblyNo. 5Repair the harness ordrive circuit short-circuitreplace the vacuum pump
assembly.
The cruise control system is notcanceled when the clutch pedalis depressed. (It is canceled, however, whenthe brake pedal is depressed.)Malfunction of the ECU
-Replace the ECU.
Damaged or disconnected
If the input checkRepair the harness, orwiring of clutch switchcode No. 26 indicatesrepair or replace the clutch
input circuita malfunction.switch.No. 7Clutch switch improper
installation (won’t switch
ON)
Malfunction of the ECU-Replace the ECU.
The cruise control system is notDamaged or disconnectedIf the input checkRepair the harness, or
canceled when the shift lever iswiring of inhibitor switchcode No. 26 indicatesrepair or replace themoved to the “N” position.
input circuita malfunction.inhibitor switch.
(It is canceled, however, when
No. 8
the brake pedal is depressed.)Improper adjustment of
inhibitor switch
Cannot decelerate by using the
SET switch.Malfunction of the ECU
Temporary damaged ordisconnected wiring of
control switch input
circuit
-
No. 2Replace the ECU.
Repair the harness orreplace the control switch
Vacuum pump assemblyNo. 5Repair the harness orcircuit poor contactreplace the vacuum puml:assembly.
Malfunction of thevacuum pump assembly
Malfunction of the ECU
-Replace the ECU.
NOTEECU: Electronic control unit
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13-162CRUISE CONTROL SYSTEM - Troubleshooting
Trouble symptomProbable causeCheck chart No.
Remedy
Cannot accelerate or resume speedOpen or short circuit in
No. 2by using the RESUME switch.RESUME switch circuit inReplace the control switch
control switch
Vacuum pump assemblyNo. 5circuit poor contactRepair the harness or
replace the vacuum pump
Malfunction of thevacuum pump assembly
(including air leaks
from negative pressurepassage)assembly.
Malfunction of the ECU-Replace the ECU.
Even when CANCEL switch is set toON, cruise control is not canceled
Open or short circuit
in CANCEL switchIf the input check
Replace the control switch
(Cruise control, however, iscode No. 27 indicatescircuit in control switch
canceled when brake pedal isa malfunction.
depressed.)No. 2
Malfunction of the ECU-Replace the ECU
The cruise control system can be set
Malfunction of theNo. 4while traveling at a vehicle speedvehicle-speed sensorRepair the vehicle speed
of less than 40 km/h (25 mph), or
circuitsensor system, or replace
there is no automatic cancellationthe part.
at that speed.Malfunction of thespeedometer cable orthe speedometer drive
gear
Malfunction of the ECU
-Replace the ECU.
The cruise control indicator light
No. 3
of the combination meter does notDamaged or disconnectedbulb of indicator lightRepair the harness or
illuminate. (But cruise controlreplace the light bulb.
system is normal)Harness damaged or
disconnected
Malfunction of the ECU
-Replace the ECU.
Cruise control ON indicator light
No. 3
does not come on. (However, cruiseBurned-out indicator lightbulbRepair the harness or
control is functional.)replace the main switch.
Open or short circuit in
harness
Malfunction of control functionby
ON/OFF switching of ELC 4 AA
accelerator switch.
(Non-operation of damper clutch,
2nd gear hold, etc.)
Overdrive is not canceled during
fixed speed driving
No shift to overdrive during
manual driving.
Malfunction of circuitrelated to acceleratorswitch OFF function
Malfunction of the ECU
Malfunction of circuit
related to overdrive
cancellation, or mal-
function of ECU
No. IO
No. 11Repair the harness or
replace the part.
Repair the harness or
replace the part.
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13466CRUISE CONTROL SYSTEM - Troubleshooting
I I4Inspection of vehicle speed sensor circuitI

IGNITIONSWITCH(IG1)
5”
El
CRUISE
CONTROL
3UNIT
cl!AI
g6pl!Ezq@zla
;i
d
“m ;ygmq%q
?
VEHICLE
SPEED
SENSOR
xX35-AR-RI304P
19Y
*
$
&
~E$iJ
0z
L
COMBINATION
METER
KX35-AK-Rl3Yla
DESCRIPTION OF OPERATION
The vehicle speed sensor, mounted in the transmission, delivers pulse signals proportional to the rotational
speed of the transmission output gear (vehicle speed) to the control unit. (Four pulse signals generated per
rotation of the output gear) Since the vehicle speed sensor is of the electronic type, the power is supplied
through the ignition switch (IG,).
The vehicle speed sensor is a reed switch type and is mounted in the speedometer. It sends pulse signals
proportional to the rotational speed of the transmission output gear (vehicle speed) to the control unit. (Four
pulse signals generated per rotation of the output gear)
TROUBLESHOOTING HINTSDiagnosis No. 12 (Automatically canceled)
ECU terminal voltage
1TerminalNo.I19
i
Signal nameCondition
Terminalvoltage
Vehicle speed sensor
Slowly drive forward with SELECT lever0 to
0.6Vat “D” or "1 st Speed”2J &l;;:neg
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