fuel pressure MITSUBISHI 3000GT 1991 User Guide

FUEL SYSTEM - Troubleshootinn
DIAGNOSISCHART (FAULT TREE)
i
L
Foutput
Diagnosis codeIreferenceDiagnosis item
Check item (Remedy)orderOutput signal patternNo.Memory
1Engine controlunit
:r- -
(Replace engine controlunit)
12A0104
2Oxygen sensorRetainedl Harness and connector(Turbo: Rear bank)
Cnn I’
0 Oxygen sensorl Fuel pressurel Injectors(Replace if defective.)
12A0104l Intake air leaks
3Air flow sensor
:n ‘*
Retainedl Harness and connector
(If harness and connector
are normal, replace air
flow sensor assembly.)
12A0104
4Intake airRetainedl Harness and connector
temperature sensorH
Ln I3
l Intake air temperature
sensor
12A0104
5Throttle position
sensor
:n I4
Retainedl Harness and connectorl Throttle position sensorl Idle position switch
12AO104
6Coolant temperature
:nn 21
Retainedl Harness and connector
sensor0 Coolant temperature
sensor12A0107
7Crank angle sensor
:nn 22
Retainedl Harness and connector
(If harness and connector
are normal, replace crank
angle sensor assembly.)
12A01078
Top dead centerRetainedl Harness and connector
sensor
:nn 23
(If harness and connector
are normal. replace crank
angle sensor assembly.)
12A0107
9Vehicle speed sensor24Retainedl Harness and connector
(reed switch)H
UInnnn
l Vehicle speed sensor
(reed switch)
L12A0107
10Barometric pressure25Retainedl Harness and connector
sensorHu I
nnluln
(If harness and connector
are normal, replace
Lbarometric pressure
12A0107sensor assembly.)
11Detonation sensor31Retainedl Harness and connector
:-r-uuuL
(If harness and connector
are normal, replace deto-
nation sensor.)
L-NOTE
12A0468
Replace the engine control unit if a malfunction code is output although the inspection reveals that there is no problem with the check
items.TSB Revision

13-14FUEL SYSTEM - Troubleshooting
routput
preference
order
7Diannosis item
Diagnosis code
IOutput signal patternNo.
36
39
121 Ignition timing
adjustment signalH
L
13Oxygen sensor ’(Turbo: Front bank)HRetainedl Harness and connectorl Oxygen sensorl Fuel pressurel Injectors (Replaceif defective)l Intake air leaks
Retained
l Harness and connectorl Injector coil resistance
5
I--
Injector12AOlO!
:nnnn
EGR
12A0105
14
41
Retainedl Harness and connectorl EGR thermo-sensorl EGRvalvel EGR control solenoidvalvel EGR valve controlvacuum
Retainedl Harness and connectorl Ignition coill Power transistor unit
16
lqnition coil,
12A0105
52power transistor unitINO. 2-5 cylinder)H
Lu Lnll
‘qnition coil.
12AO105
18Retainedl Harness and connectorl Ignition coill Power transistor unit
Retainedl Harness and connector(If harness and connector
are normal, replace only
transaxle control unit.)
Retainedl Harness and connector(If harness, connector
and induction control
valve are normal,
replace air intake
plenum assembly.)
--
Tower transistor unitH‘NO. 3-6 cylinder)
Ln
12A0105
A cable from trans-
axle control unit,Hfor transmission
of torque reductionLUUUUUI n
signal 12A0105
Induction control
valve position
61
62
sensorHLuutJvL
12A0105
Normal stateH-
NOTE-Replace the engine control unit if a malfunction code is output although the inspection reveals that there is no problem with the check
items.TSB Revision

FUEL SYSTEM - Troubleshooting13-29
ENGINE
CONTROL
RELAYF
1 7=2
c----IIIIIIII2,(2Io FUEL
) SE
PRESSURE
SOLENOID
VALVE
IfII
I
I
I
I
J
]i#&B,D i
A-20
1
WASTE
GATE
SOLENOIDVALVE
/
7 EGRi ~XE~~OID
I
; A-21
L
1 A-70
j A-72
f ENGINEj jXICI$ROL
I
-------13s
3.------
s
10
/\1
>
J
c
”-_-
1 A-18
3P
~;~E&DIAGNOSIS #Fjhl;;ON
CONNECTORADJUSTMENT
EFfq&@gCONNECTOR
d
Efpggggg]
I B-OS
ENGINE
COOLANT
Q&;EEATURE ,,'I/\FOR AIR)/@ICONDITIONEROFF --xOlJ
POWER STEERING;tK;BESSURETSB Revision

13-30FUEL SYSTEM - Troubleshooting
FUEL TANK AND FUEL LINEMlJE4AB
Symptom
Engine malfunctions
due to insufficientfuel supply
Evaporative emission
30ntroI systemmalfunctions
(When tank cap is
removed, pressure
releasing noise is
heard)
tank and fuel line
1 TSB Revision

SERVICE ADJUSTMENT PROCEDURES
MlBFHSU
BASIC IDLE SPEED ADJUSTMENT
NOTE(1) The basic idle speed has been factory-adjusted with the
speed adjusting screw (SAS) and does not normally require
adjustment.(2) If the adjustment is required, first check that the ignition
plug, injector,
ISC servo, and compression pressure are
normal.
(1) Before starting the inspection and adjustment procedures,set the vehicle in the following conditions:
l
Engine coolant temperature: 80 to 95°C (176 to 205°F)l Lights, electric cooling fan, accessories: OFF
lTransaxle: Neutral (P range on vehicles with automatic
transaxle)l Steering wheel: Straightforward position
(2) When using the multi-use tester, connect it to the diagnosis
connector.
NOTEThe connection of the multi-use tester grounds the
self-
diagnosis/data transmission selector terminal.
(3) When not using the multi-use tester, proceed as follows:
@) Insert a paper clip into the l-pin blue connector as
shown in the illustration. FUEL SYSTEM
- Service Adjustment Procedurks13-31
i
@ Connect a primary-voltage-detecting tachometer to the
paper clip.
NOTEThe
tacho/neter should read l/3 of the actual engine
speed. This means that the actual engine speed is thetachometer reading multiplied by 3.
TSB Revision

13-36FUEL SYSTEM - 0
n-vehicle Inspection of MPI Components
ON-VEHICLE INSPECTION OF MPI COMPONENTS
COMPONENTS LOCATION
EGR control solenoid valve
temperature sensor
Engine control unit
Engine coolant temperature sensor
Engine warning light
Fuel pressure control valve
Ignition coil (power transistor)
Ignition timing adjusting terminal
SSelf-diagnosis output terminal and self-diagnosis/Rdata transmission selector terminal
BTDC sensor and crank angle sensorD
PThrottle position sensor (with built-in idle switch)C
vVariable induction control servo (DC motor)J(with built-in induction control valve position
sensor)
MVehicle speed sensor (reed switch)F
QWaste gate solenoid valve U
NOTEThe “Name” column is in alphabetical order.TSB Revision

FUEL SYSTEM - 0
n-vehicle Inspection of MPI Components
AIR FLOW SENSORAir flow sensor J
III I
\I\Y7FUO941
@ Equipment side
connector
Air flow rate (liters/second)
@ Harness side
connector
I
Control relay
I
Air flow sensor
ECU
’ 7FUO654
Engine control
unit connector
7FUO653
OPERATIONl
The air flow sensor located in the air cleaner converts the engine intake air volume into a pulse signal of
frequency proportional to the air volume and inputs it to the engine control unit, which then computes thefuel injection rate, etc. based on the input signal.
l
The air flow sensor power is supplied from the control relay to the air flow sensor and is grounded in theengine control unit. The air flow sensor generates a pulse signal as it repeatedly opens and closes
between the 5 V voltage supplied from the engine control unit and ground.
TROUBLESHOOTING HINTS
Hint 1 :If the engine stalls occasionally, crank the engine and shake the air flow sensor harness. If the engineHint 2:stalls, poor contact of the air flow sensor connector is suspected.
If the air flow sensor output frequency is other than 0 when the ignition switch is turned on (but notHint 3:starting the engine), faulty air flow sensor or engine control unit is suspected.
If the engine can be run idle even though the air flow sensor output frequency is out of specification,troubles are often found in other than the air flow sensor itself.
[Examples](1) Disturbed air flow in the air flow sensor
(Disconnected air duct, clogged air cleaner element)
(2) Poor combustion in the cylinder
(Faulty ignition plug, ignition coil, injector, incorrect compression pressure, etc.)
(3) Air leaking into the intake manifold through gap of gasket, etc.
(4) Loose EGR valve seatTSB Revision

FUEL SYSTEM - On-vehicle Inspection of MPI Components13-57
INTAKE ACR TEMPERATURE SENSOR.MXWGAAZ
Air flow sensor
(with built-in intake arr-temperature sensor and
barometric pressure sensor)
temperature sensor
7FUO658
Temperature162458
@ Equipment side
connector
Air flow sensor
connector
@ Harness side
connector
r/
L
w~7X6x5x4~3x2~1j5ELl803
:
\/5“6
t
~y72 ~ [ Temperature16ZlOOt1
1
Intake air
temperature
sensor
7FU065b5v
OPERATIONl
The intake air temperature sensor converts the engine intake air temperature into a voltage and inputs it tothe engine control unit, which then corrects the fuel injection rate, etc. based on the input signal.
lThe 5 V power in the engine control unit is supplied via a resistor in the unit to the intake air temperature
sensor. Via the sensor which is a kind of resistor, it is grounded in the engine control unit. The intake airtemperature sensor resistor has such characteristic that its resistance decreases as the intake air
temperature rises.l The intake air temperature sensor terminal voltage increases or decreases as the sensor resistance
increases or decreases. Therefore, the intake air temperature sensor terminal voltage ch.anges with theintake air temperature, decreasing as the temperature rises.
TROUBLESHOOTING HINTS
The intake air temperature sensor senses the intake air temperature in the air cleaner so that it may indicate atemperature different from outside temperature depending on engine operating state.
TSB Revision

13-60FUEL SYSTEM - On-vehicle Inspection of MPI Components
BAROMETRIC PRESSURE SENSOR
Barometric
pressure sensor7FUO66
Output voltage (VI
a---l- 760Barometric pressure [mmHg (in.Hg)] (30) EC1551
@ Equipment side
M13YHAA2
d
connecror
Air flow sensor
connector
r
Barometric pressure sensor
@ Harness sideconnector
Engine control unit
A6 IA65A\72
7
7F U0664
Engine control unit connector
7FUO653
OPERATIONl The barometric pressure sensor converts the barometric pressure into a voltage and inputs it to the
engine control unit, which then corrects the fuel injection rate, etc. based on the input signal.
lThe 5 V power in the engine control unit is supplied to the barometric pressure sensor. Through the circuitin the sensor, it is grounded in the engine control unit.1
l
The barometric pressure sensor output voltage which is proportional to the barometric pressure (absolutepressure) is supplied to the engine control unit.
d ITSB Revision

FUEL SYSTEM - On-vehicle Inspection of MPI Components13-61
TROUBLESHOOTING HINTS
Hint 1 : If the barometric pressure sensor is faulty, poor driveability is caused at high altitude, in particular.
L
Hint 2: If the pressure indication of the barometric pressure sensor drops significantly during high speeddriving, check the air cleaner for clogging.
INSPECTIONUsing Multi-use Tester
Function
Data readingItem No.’ Data display
25
Check conditionAltitudeStandard value
Sensor
pressureIgnition switch: ON
At 0 m (0 ft.)760 mmHg
At 600 m (1,969 ft.)
710 mmHg
I/At 1,200 m (3,937 ft.)1660 mmHgI
At 1,800 m (5.906 ft.)610 mmHg
HARNESS INSPECTION
II
L
7FUO657
7FUO66:
Check for continuity of the ground
circuit.l Connector: Disconnected
Repair the
harness.
&@I - q ,
Measure the power supply voltage ofthe barometric pressure sensor.l Connector: Disconnected
l Ignition switch: ON
Voltaqe (V)4.8
- 5.2Repair theharness.
KgpJ-pJ,
Engine contraunit harnessside connects
Check for an open-circuit, or a short-circuit to ground between the enginecontrol unit and the barometric pres-,Y---,A
sure sensor.l
Air flow sensor connector: Dis-(OK) -+ kTOA
connectedlEngine control unit connector:
Disconnected
--I
Repair the
harness.

Jg
7FUO666
1 TSB Revision