1991 MITSUBISHI 3000GT sensor

FUEL SYSTEM - Service Adjustment Procedures13-33THROTTLE BODY
(THROTrLE VALVE AREA)
CLEANINGM13FICS
(1) Start the engine, warm it up until engine coolant tempera-ture rises to
80°C (176”F), and stop the engine.
(2) Disconnect the air intake hose at the throttle body side.
(3) Put a plug in the inlet of bypass passage in the throttle
body.
CautionNever allow cleaning agent to flow into the bypass
passage.(4) Spray cleaning agent from the intake port of the throttle
body to the valve and leave as it is for 5 minutes or so.
(5) Start the engine and race it several times. Then, run it idlefor approx. one minute.
NOTE
If the engine idle speed becomes unstable (and fails in theworst case) after plugging the bypass passage, run the
engine with the throttle valve slightly opened.
(6) If the deposit cannot be removed from the throttle valve,
repeat steps (4) and (5).
(7) Disconnect the plug from the inlet of the bypass passage.(8) Install the air ‘intake hose.
(9) Use a multi-use tester to erase the self-diagnosis code ordisconnect the battery ground cable for more than
IOseconds and then connect it again.
(lO)Adjust the basic idle speed (speed adjusting screw). (Referto
P.13-31.)
7FUO629
ADJUSTMENT OF IDLE POSITION SWITCH AND
THROTTLE POSITION SENSOR (TPS)M13FIFA(1) Disconnect the throttle position sensor connector.
(2) Using jumper wires, connect an ohmmeter across terminal
@ (idle position switch) and terminal @ (sensor ground) ofthe throttle position sensor.
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FUEL SYSTEM - Service Adjustment Procedures
(3) Insert a 0.65-mm-thick feeler gauge between the fixed SASand throttle lever.
Terminal @
(sensor output)zensor g&nd)MB991348
1
(4) Loosen the throttle position sensor mounting bolts and turnthe TPS body fully counterclockwise.
(5) In this condition, check that there is continuity across
terminals
@ and @.
(6) Slowly turn the throttle position sensor clockwise until you
find a point at which there is no continuity across terminals
@ and 0. Then, tighten the throttle position sensor
mounting bolt securely.(7) Connect the throttle position sensor connector.
(8) When using the multi-use tester, connect it to the diagnosis
connector.
(9) When not using the multi-use tester, proceed as follows:
@ Disconnect the throttle position sensor connectors andconnect the special tool, Test Harness Set, between
the disconnected connectors.
@ Connect a digital voltmeter between the throttle posi-
tion sensor terminal @ (sensor output) and teminal @
(sensor ground).
(lO)Turn the ignition switch ON (but do not start the engine).
(IlKheck the throttle position sensor output voltage.
When using the multi-use tester, select item No. 14 and
read the throttle position sensor output voltage.
Standard value: 400 - 1,000 mV
(12)lf the voltage is out of specification, check the throttle
position sensor and associated harnesses.
(13)Remove the feeler gauge.
(14)Turn the ignition switch OFF.
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1

FUEL SYSTEM - Service Adjustment Procedures13-35
ADJUSTMENT OF FIXED SASMlJFlDC
NOTE
(1) The fixed SAS has been factory-adjusted. Never attempt tomove it.
(2) Should it be out of proper adjustment, adjust by following
the procedure given below.(I) Sufficiently slacken the accelerator cable.
(2) Loosen the lock nut on the fixed SAS.
(3) Sufficiently loosen the fixed SAS by turning it counterclock-wise to fully close the throttle valve.
(4) Tighten the fixed SAS slowly to find a point at which it
contacts the throttle lever (where the throttle valve starts
opening). From that point, tighten the fixed SAS further 1 l/4
turns.
(5) Holding the fixed SAS to prevent it from turning, tighten thelock nut securely.
(6) Adjust the accelerator cable tension. (Refer to
P.13-156.)(7) Adjust the basic idle speed. (Refer to
P.13-31.)
(8) Adjust the idle position switch and throttle position sensor
(TPS). (Refer to P.13-33.)
1 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 d On-vehicle lnwection of MPI Components13-37(with built-in intakeIair temperaturesensor
Vehicle speed sensor
(reed switch)J
wF~~::~:~~or- A.anale sensor
y\\ v 7Fbd942
ii \\\ Oxygensensor,
I7FU1004
//
\:/TSB Revision

13-38FUEL SYSTEM - Onaehicle Inspection of MPI Components
I/ariableinduction control se:DC motor) (with built-in induction:ontrol valve position sensor)7FUO8
Engine warning
1 Self-diagn,osls output terminal
and self-dlagnosisi data
transmission selector terminal T37
h\s e >\\ 7FUO999Engiie
control
unit
I16FO292TSB Revision

FUEL SYSTEM - On-vehicle Inspection of MPI Components13-41
POWER SUPPLY AND IGNITION SWITCH-IG
Engine control
unit
16FO29:
Q-i=++=
iA MPI control relay
ml3Yuu
lcmition switch (IG)
@ Harness sideccmnector
62
I
Engine control unit
Engine control unit connector7FUO950
OPERATIONl
While the ignition switch is on, battery power is supplied to the engine control unit, the injector, the airflow sensor, etc.
lWhen the ignition switch is turned on, the battery voltage is applied from the ignition switch to the engine
control unit, which then turns ON the power transistor to energize the control relay coil. This turns ON thecontrol relay switch and the power is supplied from the battery to the engine control unit through the
control relay switch.
INSPECTION
Using Multi-use Tester
IFunctionItem No.Data displayICheck conditionIStandard valueI
Data reading16Engine control unit
power voltageIgnition switch: ONsv
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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