MITSUBISHI GALANT 1989 Service Repair Manual

FUEL SYSTEM -On-Vehicle lnwection of MFI Components13-259
INSPECTION
Using Scan tool
Actuator test
Item No.
07
Actuation1 Inspection conditions 1 Descriotion1 Normal condition
Actuates fuel . Engine cranking
Hold the return hose Pulsation can be felt.pump, circu-. Fuel pump forcedbetween two fingerslating fuel.
activation so as to feel the
The inspectionpulsation of the flow-
should be conducted ing of fuel.
for both of the above
conditions. Listen to the pumpPump sound can be
sound at a place near
heard.the fuel tank.
iCTlON
TGrrW’-rTTrrrrrrrrrrrrrrrrrrri 1 SAL TCheck the fuel pump._---__. Apply battery voltage to the check-ing terminal and operate the pump.
@ Harnessconnector
connector 1
sideI_
Check the ground circuit of the fuel
m-m.Connector: Disconnected
Repair theharness.
if?%d
Check for continuity between the fuel
pump and the checking terminal.
Repair theharness.
CW-
Ml)
Check for continuity between the
checking terminal and the enginecontrol module, and between themultiport fuel Injection relay termi-nals.
* Multiport fuel injection relay con-nector: Disconnected- Engine control module connec-tor: Disconnected
- ;~-:edPumpconnector: Discon-
Repair theharness.
@O-00OIHl3)
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13-260FUEL SYSTEM -On-Vehicle Inspection of MFI Components
!5J
@ Harness srdeconnector
7FUO474
Harness srdc@ connector
Engine control
module harness
side connector
7FUO475
7FUO476
@Harness side
I7FllO477
Measure the power supply voltage ofthe multiport fuel injection relay ignition switch.
Connector: Disconnected
. Ignition switch: START
(@a whenchecked). Ignition switch: ON (@@ when
Check for an open-circuit, or a short-circuit, to ground between the multi-port fuel injection relay and the en-gine control module.
. Multiport fuel injection relay con-nectar: Disconnected
. Engine control module connec-
tor: Disconnected Repair the
harness.
uziul-8)
Check for continuity, of the groundcircuit.
. Connector: Disconnected.
cl8
Repair theharness.
%ih,
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Check for an open-circuit, or a short-circuit to ground, between the multi-port fuel injection relay and the fuel
pump.- Multiport fuel injection relay con-nector: Disconnected
- nf;;;edw-wconnector: Discon-
MULTIPORT FUEL INJECTION RELAY IN
-
SPECTION
Refer to P. 13-257.

FUEL SYSTEM -On-Vehicle inspection of MFI Components13-261
VOLUME AIR FLOW SENSORMlWFAAs
/
side
@Harness side connector
I@ Harness sideconnector
Fnnine control module connector
Multiport fuel
The area enclosed with :I: is injection relay
applicable only for Turbo vehicle.
I

@I Component connector (Filter reset circuit)
Engine control module
6FU1537
Intake air amount (Wsec)
162451
OlLO838
OPERATION
l The volume air flow sensor is incorporated
within the air cleaner; it functions to convert the
amount of engine air intake to pulse signals of a
frequency proportional to the amount of engine air intake, and to input those/signals to the en-
gine control module. The engine control module
then, based upon those signals, calculates the
amount of fuel injection, etc.
TROUBLESHOOTING HINTS
HINT 1:
If the engine sometimes stalls, try starting the en-
gine and shaking the volume air flow sensor har-
ness.
If the engine then stalls, incorrect or improper con-
tact of the volume air flow sensor connector is the
probable cause.
Hint 2:
If, when the ignition switch is switched ON (but the
engine is not started), the volume air flow sensor
output frequency is any value other than zero, a
malfunction of the volume air flow sensor or of the
engine control module is the probable cause.
Hint 3:
If idling is possible even though the volume air flow
sensor output frequency is deviated from the
stand-
l The power for the volume air flow sensor is supplied from the
multiport fuel injection relay
to the volume air flow sensor, and is grounded
at the engine control module. The volume air
flow sensor, by intermitting the flow of the
5V
voltage applied from the engine control module,
produces pulse signals.
ard value, the cause is usually a malfunction other
than of the volume air flow sensor. Examples:
(1) The flow of air within the volume air flow sensor
is disturbed. (Air duct disconnection or clogged
air cleaner element)
(2) Incomplete combustion within a cylinder.(Malfunction of spark plugs, ingnition coil, injec-
tors, compression pressure, etc.)
(3) Air is taken into the intake manifold through a
leaking gasket, etc.
(4) Incomplete close contact of the EGR valve seat.
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13-262FUEL SYSTEM - On-Vehicle Inspection of MFI Components
INSPECTION
Using Scan tool
1 Data 12reading
L
Data displayInspection conditions
Sensor de-. Engine coolanttection airtemperature: 85-95°Cvolume (fre-(185-205°F)quency) .Lights, cooling fan, elec-trical accessories: OFF. Transaxle: neutral (PJTmodels: “P” range)
Engine condition
Idling
2,000 rpm
Racing
Standard value 25-50
Hz 30-50 Hz
60-90 Hz 50-80 Hz
Frequency increases as
racing rpm increases.
NOTEThe volume air flow sensor output frequency may be about 10% higher than\
indicated above when the vehicle is new
[driven approximately 500 km(300 miles) or less].
i
Regular waveform03AO203
HARNESS INSPECTION Using Oscilloscope
(1) Run the engine at idle speed.
(2) Connect the probe to the osilloscope
pick-up point as
shown in the circuit diagram, and check the wave form.
Measure the terminal voltage.
. Connector: Disconnected
. Ignition switch: ON
connectorOlMaa
Measure the power supply voltage.
. Connector: Disconnected
. Ignition switch: ON
Harness side
connectorthe multiport fueinjection relay.
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FUEL SYSTEM - On-Vehicle Inspection of MFI Components13-263

Check for continuity of the ground
circuit of the VAF sensor.
. Connector: Disconnected
\--connector
4Harness side Check for continuity between the
en-3 air__.. --.. ..-gine control moduie and volumt
UIIflow sensor.Y---L1 A
. Engine control module connec-
tor: Disconnected- Volume air flow sensor connec-tor: Disconnected
kTOA
Repair theharness.
NliwHBl)
DlAO!XO
MlJYGAAlUTAKE AIR TEMPERATURE SENSORI
I
Temperature-Temperature1621008
142454
-
sensor connector , Intake air temperature sensorIntake air
temperature sensor
I24
Intake air
@I Harness side
connector@I Harness side
.8.I
4Enginecontrol
module 5V
I1
6FU1298
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13-264FUEL SYSTEM - On-Vehicle Inspection of MFI Components
OPERATION
l The intake air temperature sensor functions to
convert the temperature of the air (intaken to the
engine) to voltage, and to input that voltage (as
signals) to the eingine control module. The en-
gine control module, based upon those signals,
then corrects the amount of fuel injection, etc.
lThe 5V power supply within the engine control
module is supplied, by way of the resistance
within the unit, to the intake air temperature
sensor; it passes through the intake air temper-
ature sensor, which is a type of resistor, and is
grounded at the engine control module.
Note that the resistance of the intake air
temperaturesensor decreases when the
temperature of the intake air increases.
* The intake air temperature sensor terminal
voltage becomes higher when the resistance of
the intake air temperature sensor increases, and becomes lower when the resistance decreases.
Consequently, the intake air temperature sensor
terminal voltage varies in accordance with the
temperature of the intake air, becoming lower
when the temperature of the intake air
in-
creases.
TROUBLESHOOTING HINTS
Because the intake air temperature sensor detects
the temperature of the intake air in the air cleaner, it
indicates a temperature different than the tempera-
ture of the outside air when the engine is running.
INSPECTION
Using Scan tool
Function
Data reading Item No.
13
Data display
Sensor de-
tection
temperature
HARNESS INSPECTION
II
>
7 7
h
I
Check conditions
Ignition switch: ONOr, engine running
Intake air temp.At -20°C (-4°F)
At 0°C (32°F)
At 20°C (68°F)
At 40°C (104°F)
At 80°C (176°F)
Standard value -20°C
0°C
20°C
40°C
80°C
Measure the power supply voltage.
- Connector: Disconnected. Ignition switch: ON
j
/‘“:;~~~v’0OKLl2
Repair theharness.
Cm--a
oE!l-@)
Check for continuity of the glroundcircuit of the intake air temperaturesensor.
. Connector: Disconnected
I
sidevI I 1~ I
I
Harness fi
connector ‘-------i01A051.1
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FUEL SYSTEM -On-Vehicle Inspection of MFI Components13-265

>
Volume air flow sensor
side connector

I J
1
I
6FUO62:-I
r
rature sensor
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:Turbo>
lerature sensor,$kpntak _-.-.- --
i\PJtemp -
-“, ’
w\
SENSOR INSPECTION
(1) Disconnect the volume air flow sensor connectors.
(2) Measure resistance between terminals @ and @. (3)
Er$%e resistance between terminals @ and 0,.

Temperature “C (“F)
0 (32)
20 (68)
80 (176)
Resistance (kQ)
6.0
2.7
0.4
(3) Measure resistance while heating the sensor using a hair
drier.
Temperature “C (“F)
Higher
Resistance (kR)
Smaller
(4) If the value deviates from the standard value or the resist- ance remains unchanged, replace the volume air flow sen-
sor assembly.

13-266FUEL SYSTEM - On-vehicle Inspection of MFI Components
BAROMETRIC PRESSURE SENSORMl3VHPYPl
\ Volume air
Barometric
pressure
sensor
Output Voltage
/-4
3
2
1
v 0LzLBarometric pressure mmHg 760 ~~1551
EC1537
(
7
\
‘i
6!
I
I1(
B Volume air flow@ Volume air flowsensor connector sensor connector
5EL1600, L-@I Harness sideconnector@Harness sidernnn~rtnr131 11, I ’““, ,. Iv-.-.,\L4 ,\-5A17 h24
Fnnine 1Anv uI
Barometric pressure sensor
-“J -control
module
I
OllO537
Engine control module connector
01 LOB38
OPERATION
l The barometric-pressure sensor functions to
convert the barometric pressure to voltage, and
to input that voltage (as signals) to the engine
control module.
The engine control module, based upon those
signals, then corrects the amount of fuel injec-
tion, etc.
TROUBLESHOOTING HINTS Hini 1:
If there is a malfunction of the barometric-pressure
sensor,
driveability of the vehicle will become worse
particularly at high altitude.
lThe 5V power supply within the engine control
module is supplied to the barometric-pressure
sensor; it passes through the circuitry within the
sensor, and is grounded at the engine control
module.
lThe barometric-pressure sensor output voltage is sent to the engine control module in propor-
tion to the barometric pressure (absolute pres-
sure).
Hint 2:
If. during high-speed driving, there is a noticeable
sharp drop of the displayed pressure of the
barometric-pressure sensor, check for clogging of
the air cleaner.
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FUEL SYSTEM -On-Vehicle inspection of MFI Components13-267
INSPECTION
Using Scan tool
Function Item No.
Data display
Data reading
25Sensor detec-tion pressure
HARNESS INSPECTION
Check conditions1 Altitude1 Standard value
lanltion switch: ON1 At 0 m (0 ft.)LrnmmHq
At 600 m(1,969 ft.)710 mmHg
At 1,200 m660 mmHg(3,937 ft.)
At I:800
m610 mmHg
(5,906 ft.)
. Connector:Disconnected
Measure the power supply voltage Ofthe barometric pressure sensor.
connector
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-Engine controlmodule harness
side connector
6%
-

Check for an open-circuit, or a shqrt-circuit to ground, between the enginecontrol module and the barometricpressure sensor.
. Volume air flow sensor connec-tor: Disconnected@--/LA
- Engine control module connec-tor: Disconnected

13-26813-268FUEL SYSTEM -FUEL SYSTEM -On-Vehicle Inspection of MFI Components
On-Vehicle Inspection of MFI Components
ENGINE COOLANT TEMPERATURE SENSOR
ENGINE COOLANT TEMPERATURE SENSORMl3YIABlMl3YIABl
Coolant temperature
Coolant temperature 1ez4sa
Coolant temperature
Coolant temperature
16210081621008
t+arness s,de C
ompone
nt side
Engine coolant temperature sensorIconnector
connectori- ,
Jr
Engine
control module
Ih5v
6FU1239
OPERATION
l The engine coolant temperature sensor func-
tions to convert the barometric pressure to vol-
tage, and to input that voltage (as signals) to the
engine control module.
The engine control module, based upon those signals, regulates the amount of fuel injection
and the fast-idling speed when the engine is
cold.
lThe 5V power supply within the engine control
module is supplied, by way of the resistance
within the unit, to the engine coolant tempera-
ture sensor; it passes through the engine
coolant temperature sensor, which is a type of
resistor, and is grounded at the engine control
module.
TROUBLESHOOTING HINTS
If, during engine warm-up, the fast-idling speed is
not correct, or black smoke is emitted, the problem
Note that the resistance of the engine coolant
temperature sensor decreases when the tem-
perature of the coolant increases.
l The engine coolant temperature sensor terminal
voltage becomes higher when the resistance of
the engine coolant temperature sensor in-
creases, and becomes lower when the resist-
ance decreases. Consequently, the engine
coolant temperature sensor terminal voltage va-
ries in accordance with the temperature of the
coolant, becoming lower when the temperature
of the coolant increases.
is usually a malfunction of the engine coolant tem-
perature sensor.
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