ignition MITSUBISHI 3000GT 1991 Workshop Manual

1
FUEL SYSTEM- On-vehicle InsDection of MPI ComDonents13-99
HARNESS INSPECTIONl Connector: Disconnected
l Ignition switch: ON
Engine control
Check for an open-circuit, or a short-circuit to ground, between the engine
control unit and the oxygen sensor.
lOxygen sensor connector: Dis-connectedlEngine control unit connector:
Disconnected
Repair the-+ harness.
3Check for continuity of the ground
- @@
Harness sidecircuit.l Connector: Disconnected
Repair the
harness.
7FUO512
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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- Ori-vehicle lnwection of MPI ComDonents13403
+/A+ A: Injector drive time
Normal waveform03A0201
HARNESS INSPECTION
--J1
Harness side
7FlJO669
* I
@
Harness side
connector
1 HarnessJPside =connector7FUO805
Using Oscilloscope
(1) Run the engine at idle speed.
(2) Connect the probe to the oscilloscope pick-up point as
shown in the circuit diagram, and check the waveform at
the drive side of each injector.
Measure the power supply voltage of
the front bank injector.
-
l Connector: Disconnectedl Ignition switch: ON
1
Repair the
harness.
(m-Control relay)
Measure the power supply voltage ofthe rear bank injector.
l Connector: Disconnectedl Ignition switch: ON
Voltage
(VI
svRepair the
harness.
(m - Con-
trol relay)
Check for an open-circuit, or a
short-circuit between the front bank injectorand the engine control unit.
l Injector connector: DisconnectedlEngine control unit connector:
Disconnected
id
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-107
HARNESS INSPECTION
@ Harness sideconnector
I
I
7FUO976
Measure the power supply voltage of
the resistor.
l Resistor connector: Discon-
nectedl Ignition switch: ON
connector
7FUO669-I
3Rear bank
harness side
connector
.------------------’7FUO97;
Harness sideconnectorz7FUO805
Measure the power supply voltage of
the front bank injector.
l Resistor connector: Connected0 Injector connector: Disconnected
l Ignition switch: ON
Voltage
(V)
0
OK03
Repair the
harness.
(@g@pJ-Control relay)Check power
supplyCheck resis-tor
Measure the power supply voltage ofthe rear bank injector.l Connector: Disconnected
l Ignition switch: ON
*
04
Repair the
supply’Check resis-tor
Check for an open-circuit, or a short-circuit between the front bank injector
and the engine control unit.
f---l -
l Injector connector: DisconnectedlEngine control unit connector:
Disconnected
1
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13-110FUEL SYSTEM - On-vehicle Inspection of MPI Components
IDLE SPEED CONTROL SERVO (STEPPER MOTOR TYPE)\
7FUO64;Ball beam
‘9
L PlntleControl relay
@ Harness side
connector
\/1, \,\/“1“3 “4 “6Idle speed
control servo
OSCIIIOOSCIIIOOSClllOosclllomu--
/(a /(IT ),!j /I,, Enginecontrol unit
BPPP
7FUO518Engine control unit connector
7FUO653
OPERATION
lThe intake air volume during idling is controlled by opening ‘or closing the servo valve provided in the air
path that bypasses the throttle valve.’
lThe servo valve is opened or closed by operating the stepper motor in the speed control servo in normal or
reverse direction.
lThe battery power is supplied to the stepper motor through the control relay. As the engine control unit
turns on power transistors in the unit one after another, the stepper motor coil is energized and the motor
rotates in normal or reverse direction.
TROUBLESHOOTING HINTSHint 1:If the stepper motor step increases to 100 to 120 steps or decreases to 0 step, faulty stepper motor
or open circuit in the harness is suspected.
Hint 2: If the idle speed control servo harness and individual part checks have resulted normal but the
stepper motor steps are out of specification, the following faults are suspected.
(I) Poorly adjusted reference idle speed
(2) Deposit on the throttle valve
(3) Air leaking into the intake manifold through gasket gap
(4) Loose EGR valve seat
(5)Poor combustion in the cylinder (faulty ignition plug, ignition coil, injector, low compression
pressure, etc.)
\L.J
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13-112FUEL SYSTEM - 0
n-vehicleInspection of MPI Components
HARNESS INSPECTION
Measure the power supply voltage ofidle speed control servo.l
Idle speed control servo connec-tor: Disconnectedl Ignition switch: ON
Connector
connector
OlLO395- WI)
Engine control
Check for an open-circuit, or a short-circuit to ground between the enginecontrol unit and the idle speed control
servo.l
Engine control unit connector:
Disconnectedl
Idle speed control servo connec-tar: Disconnected
ACTUATOR I’NSPECTIONChecking the Operation Sound
(1)Check that the operation sound of the stepper motor can be
heard after the ignition is switched ON (but without starting
the motor).
(2) If the operation sound cannot be heard, check the stepper
motor’s activation circuit.
If the circuit is normal, it is probable that there is a
malfunction of the stepper motor or of the engine control
unit.
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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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