1991 MITSUBISHI 3000GT Service Manual

FUEL SYSTEM - Troubleshooting13-15READ OUT OF MALFUNCTION CODE
Precautions for Operation
(1) When battery voltage is low, no detection of failure is
possible. Be sure to check the battery for voltage and otherconditions before starting the test.
(2) Diagnosis item is erased if the battery or the engine controlunit connector is disconnected. Do not disconnect the
battery before the diagnosis result is completely read.
Using Multi-Use Tester
(I) Read and record the self-diagnosis output.
(2) Referring to the diagnosis chart, repair the faulty part.
(3) Turn the ignition switch OFF and then turn it ON.
(4) Erase the malfunction code.(5) Recheck that a normal code is output.
7FUO999
r MPI diagnosis
L Ground
EC165(Using Voltmeter(I) Connect an analog voltmeter between the self-diagnosis
output terminal of the diagnosis connector and ground
terminal.(2) Turn on the ignition switch.
(3) Read the diagnosis output pattern from the voltmeter and
record it.(4) Referring to the diagnosis chart, repair the faulty part.
(5) Erase the malfunction code using the following procedure.
@ Turn OFF the ignition switch.
@ Disconnect the negative battery cable from the battery
terminal for
10 seconds or more and then reconnect it.
@ Turn ON the ignition switch and read the self-diagnosiscode to check that a normal code is output.
Diagnosis by DIAGNOSIS 2 MODE
(1) Using the multi-use tester, changeover the diagnosis modeof the engine control unit to DIAGNOSIS 2 MODE.
(2) Road test the vehicle.
(3) Read the diagnosis code in the same manner as “READ
OUT OF MALFUNCTION CODE” and repair the malfunc-
tioning part.(4) Remove the multi-use tester.
NOTERemoval of the multi-use tester
.will erase all the self-’
diagnosis malfunction codes in the engine control unit and
changeover the diagnosis mode from DIAGNOSIS 2 MODEto DIAGNOSIS 1 MODE.
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13-16FUEL SYSTEM - Troubleshooting
CHECK CHART CLASSIFIED BY PROBLEM SYMPTOMSstepper motor type)
0:Warmen,gine (number inside indicates check order)Cl: Cold engine (number inside indicates check order): Non TurboCT>: TurboTSB Revision

FUEL SYSTEM - Troubleshootina13-17
PROBLEM SYMPTOMS TABLE (FOR YOUR INFORMATION)
I;
L
/
L/
Items
Won’t start(no initial combustion)-g Starting problem
2(i;il;i combustion, then
Symptom
The starter is used to crank the engine, but there is no combustion within the
cylinders, and the engine won’t start.
There is combustion within the cylinders, but then the engine soon stalls.(Starting takes a long
time.)Engine won’t start quickly.
Idling instability
(Rough idling)Engine speed doesn’t remain constant; changes during idling.Usually, a judgement can be based upon the movement of the tachometer
>.rpointer, and the vibration transmitted to the steering wheel, shift lever, body, etc.
EThis is called rough idling.
s0
Incorrect idling speedThe engine doesn’t idle at the usual correct speed.
F.-=e-ImpDr;p;ertidling continuityThis non-continuity of idling includes the following elements.(1) Die outPass out. . . . . The engine stalls when the foot is taken from the accelerator pedal,regardless of whether the vehicle is moving or not.(2) Pass out . . The engine stalls when the accelerator pedal is depressed or while
it is being used.
Hesitation
Sag
“Hesitation” is the delay in responseHesitation
of the vehicle speed (engine rpm) thatLNormaloccurs when the accelerator pedal is
depressed in order to accelerate from---
the speed at which the vehicle is nowx\a,r- ,
traveling, or a temporary drop in vehi-g Initialv) accelerator**’ ,8’ /cle speed (engine rpm) during such+ pedal/,’ /
’
acceleration.2 depression
Serious hesitation is called “sag”.2
1“*’.’
/’ ,’I&L-e**’Ii Sag
Poor acceleration
Time1 FU022:
Poor acceleration is inability to obtain an acceleration corresponding to thedegree of throttle opening, even though acceleration is smooth, or the inability toreach maximum speed.
0, Stumble.F
‘iIn
Engine rpm response is delayed when
the accelerator pedal is initially.
depressed for acceleration from thestopped condition.
$Normal
x
:Initial
3acceleratorI//
c
-7
pedal2 depression,#’,
4,/Idling *--’Stumble
Shock
cTime1 FUO22L
The feeling of a comparatively large impact or vibration when the engine isaccelerated or decelerated.
SurgeThis is repeated surging ahead during constant speed travel or during variable
speed travel.
Knocking
A sharp sound like a hammer striking the cylinder walls during driving and which
adversely affects driving.TSB Revision

13-18FUEL SYSTEM - Troubleshooting
CIRCUIT DIAGRAM
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IKX35-AC-R0502-NY
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FUEL SYSTEM - Troubleshooting
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UNIT
PTSB Revision

13-20FUEL SYSTEM - Troubleshooting
CRANK ANGLEAND TOP DEAD z
BCENTER SENSOR $j
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SENSOR
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1 TSB Revision

FUEL SYSTEM - Troubleshootinn13-21
ENGINE
CONTROL
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IDLE SPEED sgCONTROL
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SERVO MOTOR
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A-22@&TSB Revision

13-22FUEL SYSTEM - Troubleshooting
J/B
(MULTI-PURPOSEFUSE@>TAIL LIGHTRELAYiE;;FGER ikli$IC
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POWER TRANSISTOR
ENGINE
COOLANT
TEMPERATURE.SWITCH
(FOR AIR
CONDITIONER)AIR~X$Il$T~ONER
UNITKX35-AC-R05025-NY
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