fuel MITSUBISHI 3000GT 1991 Service Manual

idFUEL SYSTEM
- On-vehicle Inspection of MPI Components13-113
‘El
‘a
~
63
7FUOOlO(stepper motor)
7FUO98CIdle speed
MD998463
7FUOO78
Checking the Coil Resistance(1) Disconnect the idle speed control servo connector and
connect the special tool (test harness).
(2) Measure the resistance between terminal @ (white clip of
the special tool) and either terminal @ (red clip) or terminal@ (blue clip) of the connector at the idle speed control
servo side.
Standard value: 28
- 33 !2 at 20°C (68°F)
(3) Measure the resistance between terminal @ (green clip of
the special tool) and either terminal @ (yellow clip) or
terminal @ (black clip) of the connector at the idle speed
control servo side.
Standard value: 28
- 33 CR at 20°C (68°F)
Operational Check(1) Remove the throttle body.
(2) Remove the stepper motor.
(3) Connect the special tool (test harness) to the idle speed
control servo connector.
(4) Connect the positive
0 terminal of a power supply (approx
6 V) to the white clip and the green clip.
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13-114FUEL SYSTEM - On-vehicle Inspection of MPI Components
(5) With the idle speed control servo as shown in the
illustration, connect the negative
0 terminal of the power
supply to each clip as described in the following steps, and
check whether or not a vibrating feeling (a feeling of very
(slight vibration of the stepper motor) is generated as aJresult of the activation of the stepper motor.@Connect the negative
0 terminal of the power supply to
the red and black clip.@Connect the negative
0 terminal of the power supply to
the blue and black clip.@Connect the negative
0 terminal of the power supply to@the blue and yellow clip.
Connect the negative
0 terminal of the power supply to
the red and yellow clip.@Connect the negative
0 terminal of the power supply to
the red and black clip.@ Repeat the tests in sequence from @ to
0.(6) If, as a result of these tests, vibration is detected, the
stepper motor can be considered to be normal.
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FUEL SYSTEM - On-vehicle Inspection of MPI Components
IGNITION COIL AND POWER TRANSISTOR
MlBYVABEquipment side
connector@ Harness side
connector@ Harness side connector
Tachometer
-1Battery
/gnition coil1 3
Engine control unit
\/\/\IAL“8 “6.,,523No. 2No. 3
No 5No. 6
* transistor
5Y
lgnltlontamingadjust-
mentconnectof
11104
d
w5V
7FU1059Engine control unitconnector
7FUO453
OPERATION
lWhen the power transistor unit A is turned on by the signal from the engine control unit, primary current
flows to the ignition coil A. When the power transistor unit A is turned off, the primaty current is shut off
and a high voltage is induced in the secondary coil A, causing the ignition plugs of No. 1 and No. 4
cylinders to spark. When the
power transistor unit B is turned off, the ignition plugs of No. 2 and No. 3
cylinders spark.
L
lWhen the engine control unit turns off the transistor in the unit, the battery voltage in the unit is applied to
the power transistor unit to turn it on. When the engine control unit turns on the transistor in the unit, the
power transistor unit is turned off.
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13-116FUEL SYSTEM - 0
n-vehicle Inspection of MPI Components
INSPECTION
Using Multi-use Tester
(d
FunctionItem No. Data displayCheck condition
Engine state
Standard valueData reading 44
Ignitionadvancel Engine: Warming up
750 rpm (Idle)7 - 23”BTDCl Timing light: Set (settiming light to check2,000 rpm30 - 40”BTDC actual ignition timing)28 - 35”BTDC

‘
Function
Data listItem No.Data displayCheckTerminalStandard value
condition
condition
36Continuity present or
not present betweenl Engine:
IdlingIgnition timing ad-ON
ignition timing adjustmentjustment terminal isterminal and groundgrounded
Ignition timing ad-OFFjustment terminal is
disconnected from
ground
Function
Actuator testItem No.
DriveCheck conditionNormal condition
17Set to ignition timingl Engine: idling5”BTDCadjustment model Timing light: set\
($Gizi)
IJ
\LIOV _
ovep~,. ..~_~.~ fA t---.-
I
Normal waveform03AO207
(
j /’ II
IOV _I ’/
/ 1ovIJ
Normal waveform
Using Oscilloscope1. Primary signal of ignition coil
(I) Run the engine at an idle revolution speed.
(2) Connect the probe to oscilloscope pick-up point 1 as
shown in the circuit diagram, and check the primary
signal of the ignition coil.
2. Control signal of power transistor
Connect the probe to oscilloscope pick-up point
2 as shown
in the circuit diagram, and check the control signal of the
power transistor.
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-117
HARNESS INSPECTION
connectorl Connector: Disconnected
l Ignition switch: ON
Check for an open-circuit, or a short-
P
circuit to ground between the engine
control unit and the power transistor.l
Engine control unit connector:
Disconnectedl
Power transistor connector: Dis-connectedEngineRepair thecontrolunit-+ harness.harness(@@J-1101/)stdeconnector
T6FU1251
Check for an open-circuit, or a short-circuit to ground between the power
transistor and the ignition coil.l
Ignition coil connector: Discon-netted
l
Power transistor connector: Dis-
connected
Repair the
7FUO699
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13-118FUEL SYSTEM- On-vehicle Inspection of MPI Components
connector
7FUO700
7FUO701
Check for continuity of the ground
circuit.
(1Il Connector: Disconnected
Repair the
harness.@pJ
-Ground)
Measure the voltage of the controlslgnal circuit of the power transistor.l Connector: Disconnected
l
lgnrtion switch: START
Voltage
(VI0.5
- 4.0
f
q7
Repair the
harness.
Measure the voltage of the ignition
timinq adiustment terminal.
- _l Ignition switch: ON
Voltage
(V)4.0
- 5.2
ACTUATOR INSPECTIONRefer to GROUP 16
- Ignition System.
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-119PURGE CONTROL SOLENOID VALVE
Q Harness side
connector
I
Control relay
@ Equipment side
connector connector
unit
OlAO324
Engine control unit connector
7FUO653OPERATION
lThe purge control solenoid valve is an ON-OFF type one which controls introduction of purge air from the
canister into the intake air plenum.
lThe battery power is supplied to the purge control solenoid valve through the control relay. When the
engine control unit turns ON the power transistor in the unit, current flows to the coil, introducing purge
air.
INSPECTION
Using Multi-use Tester
Function
Actuator testItem No.Drive content
Check conditionNormal state
08Solenoid valve from OFFIgnition switch: ONOperating sound is heard
to ONwhen driven
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13-120FUEL SYSTEM - On-vehicle Inspection of MPI Components
HARNESS INSPECTION
@ Harness side
connector
T7FUO525
I -connector57FUO526
1
Measure the power supply voltage.
l Connector: Disconnected0 Ignition switch: ON
Check for an open-circuit, or a short-circuit to ground between the purgecontrol solenoid valve and the engine
control unit,
lEngine control unit connector:
Disconnected@-+A
lPurge control solenoid valve con-nector: DisconnectedRepair the
harness.

ACTUATOR INSPECTIONRefer to GROUP 17
- Evaporative Emission Control System.
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FUEL SYSTEM - On-vehicle lnwection of MPI ComDonents13-121
LEGR CONTROL SOLENOID VALVE - Non Turbo, Turbo>MlBYZBAControl relav
EGR control
solenoid valve@ Equipment side
connector
Engine
control
unitEngine control unit connector
7FUO653
OPERATION
lThe EGR control solenoid valve is a duty control type solenoid valve. It makes control by leaking EGR valve
operating negative pressure to the throttle body A port.
lPower supply from the battery is sent through the control relay to the EGR control solenoid valve. When
the engine control unit turns off the power transistor inside the unit, current no more flows through the
coil and EGR valve operating negative pressure leaks.
TROUBLESHOOTING HINTIf the results of EGR control solenoid valve on-vehicle and off-vehicle inspections are normal but the
self-diagnosis code for EGR system failure is displayed, check the EGR valve, vacuum hose and EGR passage
for blocking.
c.
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13-122FUEL SYSTEM - On-vehicle Inspection of MPI Components
INSPECTIONUsing Multi-use Tester
Function
Actuator testItem No.
Drive content
Check condition
Normal state
10Change solenoid valve
from OFF to ON stateIgnition switch: ONOperating sound is heardwhen driven
HARNESS INSPECTION
1
@ Harness side
connector
Measure the power supply voltage.
Y01105*4Engine control unit
harness side connector
Control relay)
Repair the
-S harness.C@vJ-~)
d
Ls
ACTUATOR INSPECTIONRefer to GROUP 17
- Exhaust Gas Recirculation (EGR) System.
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