
MPI -TroubleshootingMPI -Troubleshooting13A-109
Engine-ECU Connector Terminal Arrangement
Terminal No.Check itemCheck condition (Engine condition)Normal condition
1No. 1 injectorWhile engine is idling after having warmed up,
suddenlydepresstheacceleratorpedal
From 11 - 14 V, momentarily
dropsslightly
14No. 2 injector
suddenlydepressthe accelerator pedal.drops slightly
2No. 3 injector
15No. 4 injector
3Fuel pressure control
solenoidvalve
Ignition switch: “ON”System voltage
solenoidvalve
Engine: Cranking→Idle operation
(within approximately 2 minutes or less)1 V or less→System voltage
4Stepper motor coil
startedSystem voltage↔0-6V
(Changes repeatedly)
17Stepper motor coil
5Stepper motor coil
18Stepper motor coil
6EGR control solenoid
valve
Ignition switch: “ON”System Voltage
valve
While engine is idling, suddenly depress the
accelerator pedal.From system voltage,
momentarily drops
8A/C relayDEngine: Idle operation
DA/Cswitch:OFF→ON(A/Ccompressor
System voltage or momen-
tarily6Vormore→1VorDA/Cswitch:OFF→ON(A/Ccompressor
runs)tarily6Vor more→1Vor
less
9Purge control sole-
noidvalve
Ignition switch: “ON”System voltage
noidvalve
Engine: Idle operation1 V or less
10Ignition coil - No.1,
No.4Engine speed: 3,000 r/min0.3 - 3.0 V
23Ignition coil - No.2,
No.3
11Waste gate solenoid
valve
Ignition switch: “ON”System voltage
valve
Engine: After warm-up, idle operation
(When using premium gasoline)1 V or less

MPI -Troubleshooting13A-111
Terminal No.Normal condition Check condition (Engine condition) Check item
37Power steering fluid
pressure switchEngine: Idling after
warming upWhen steering wheel
is stationarySystem voltage
When steering wheel
is turned1 V or less
38Engine control relayIgnition switch: “LOCK” (OFF)System voltage
Ignition switch: “ON”1 V or less
39Fuel pump relay 3While engine is idling, suddenly depress the
accelerator pedal.Temporarily rises slightly
from 1 V or less.
41Alternator FR
terminalDEngine: After warm-up, idle operation
DRadiator fan: Not operating
DHead lamp: OFF→ON
DStop lamp: OFF→ON
DRear deffogger switch: OFF→ONVoltage decrease
44Intercooler water
spray switch (Auto)DIgnition switch: “ON”
DIntercooler water spray switch: ON1 V or less
DIgnition switch: “ON”
DIntercooler water spray switch: OFFSystem voltage
45A/C switchEngine: Idle operationTurn the A/C switch
OFF0.5 V or less
DA/C switch: ON
DA/C setting
temperature
When room tem-
perature is 25_C
or more: Max
Cool
When room tem-
perature is 25_C
or less: Max. HotSystem voltage
53Secondary air control
solenoid valveIgnition switch: “ON”System voltage
54Oxygen sensor
heater(Rear)
Engine: Idling after warming up1 V or less
heater(Rear)
Engine speed: 5,000r/minSystem voltage
55Intercooler water
sprayrelay
Ignition switch: “ON”System voltage
spray relay
Ignition switch: “LOCK” (OFF)1 V or less
58Tachometer signalEngine speed: 3,000r/min0.3 - 3.0 V
60Oxygen sensor
heater(front)
Engine: Idling after warming up1 V or less
heater(front)
Engine speed: 5,000r/minSystem voltage
71Ignition switch - STEngine: Cranking8 V or more

MPI -Troubleshooting13A-112
Terminal No.Normal condition Check condition (Engine condition) Check item
72Intake air
temperature sensorIgnition switch: “ON”Intake air
temperature: - 20_C3.8 - 4.4 V
Intake air
temperature: 0_C3.2 - 3.8 V
Intake air
temperature: 20_C2.3 - 2.9 V
Intake air
temperature: 40_C1.5 - 2.1 V
Intake air
temperature: 60_C0.8 - 1.4 V
Intake air
temperature: 80_C0.4 - 1.0 V
75Oxygen sensor
(Rear)DTransmission: Second gear
DDriving with the throttle widely open
DEngine: 3,500 r/min or more0.6 - 1.0 V
76Oxygen sensor (front)Engine: Running at 2,500 r/min after warmed
up (Check using a digital type voltmeter)0↔0.8 V
(Changes repeatedly)
80Backup power supplyIgnition switch: “LOCK” (OFF)System voltage
81Sensor impressed
voltageIgnition switch: “ON”4.9 - 5.1 V
82Ignition switch - IGIgnition switch: “ON”System voltage
83Engine coolant
temperature sensorIgnition switch: “ON”Coolant temperature:
-20_C3.9 - 4.5 V
Coolant temperature:
0_C3.2 - 3.8 V
Coolant temperature:
20_C2.3 - 2.9 V
Coolant temperature:
40_C1.3 - 1.9 V
Coolant temperature:
60_C0.7 - 1.3 V
Coolant temperature:
80_C0.3 - 0.9 V
84Throttle position
sensorIgnition switch: “ON”Set throttle valve to
idle position0.535 - 0.735 V
Fully open throttle
valve4.5 - 5.0 V
85Barometric pressure
sensor
Ignition switch: “ON”Altitude: 0 m3.8 - 4.2 V
sensor
Altitude: 600 m3.5 - 3.9 V
Altitude: 1,200 m3.2 - 3.8 V
Altitude: 1,800 m3.0 - 3.4 V

MPI -Troubleshooting13A-115
Terminal No. Normal condition (Check condition)Inspection item
3-12Fuel pressure control solenoid valve28 - 36Ω(at 20_C)
4-12Stepper motor coil (A1)28 - 33Ω(at 20_C)
17 - 12Stepper motor coil (A2)
5-12Stepper motor coil (B1)
18 - 12Stepper motor coil (B2)
6-12EGR control solenoid valve36 - 44Ω(at 20_C)
9-12Purge control solenoid valve22 - 26Ω(at 20_C)
11 - 1 2Waste gate solenoid valve62 - 74Ω(at 20_C)
13 - Body earthENGINE-ECU earthContinuity (0Ω)
26 - Body earthENGINE-ECU earth
53 - 12Secondary air control solenoid valve28 - 36Ω(at 20_C)
54 - 12Oxygen sensor heater (Rear)11 - 1 8Ω(at 20_C)
60 - 12Oxygen sensor heater (Front)4.5 - 8.0Ω(at 20_C)
72 - 92Intake air temperature sensor13 - 17 kΩ(When intake air temperature is - 20_C)
5.7 - 6.7 kΩ(When intake air temperature is 0_C)
2.3 - 3.0 kΩ(When intake air temperature is 20_C)
1.0 - 1.5 kΩ(When intake air temperature is 40_C)
0.56 - 0.76 kΩ(When intake air temperature is 60_C)
0.30 - 0.42 kΩ(When intake air temperature is 80_C)
83 - 92Engine coolant temperature sensor14 - 17 kΩ(When coolant temperature is - 20_C)
5.1 - 6.5 kΩ(When coolant temperature is 0_C)
2.1 - 2.7 kΩ(When coolant temperature is 20_C)
0.9 - 1.3 kΩ(When coolant temperature is 40_C)
0.48 - 0.68 kΩ(When coolant temperature is 60_C)
0.26 - 0.36 kΩ(When coolant temperature is 80_C)

MPI -On-vehicle Service13A-126
THROTTLE BODY (THROTTLE VALVE AREA)
CLEANING
1. Remove the air intake hose from the throttle body.
2. Spray cleaning fluid on a clean cloth.
3. Wipe off the dirt around the throttle valve with the cloth
sprayed with cleaning fluid.
Caution
(1) Do not spray the cleaning fluid directly to the
throttle valve.
(2) Make sure the cleaning fluid does not enter the
motor from the bypass line. Also make sure it
does not enter the sensor through the shaft.
(3) Be careful not to rub off the molybden applied
around the throttle valve shaft.
4. Attach the air intake hose.
5. Adjust the basic idle speed. (Refer to P.13A-127.)
THROTTLE POSITION SENSOR ADJUSTMENT
1. Connect the MUT-IIto the diagnosis connector.
When not using the MUT-II, proceed as follows:
(1) Disconnect the throttle position sensor connector, and
connect the special tool (test harness: MB991536)
between the disconnected connector taking care not
to confuse the terminal to be connected.
(2) Connect digital voltmeter between the terminal No.
2 and the terminal No. 4 of the throttle position sensor
connector.
2. Turn the ignition switch to “ON” position (but do not start
the engine).
3. Check the output voltage of the throttle position sensor.
Standard value: 535 - 735 mV
Throttle valve molybdenum
application section15 mm
15 mm
Equipment side connectorThrottle
position
sensor
Throttle
body
MB991536
Throttle position sensor

MPI -On-vehicle Service13A-127
4. If not within the standard value, loosen the throttle position
sensor mounting bolts. Then rotate the sensor body to
adjust.
5. Turn the ignition switch to “LOCK” (OFF) position.
6. Remove the MUT-II. If the MUT-IIis not used, remove
the special tool, and then connect the throttle position
sensor connector.
7. If a diagnosis code is displayed, erase the diagnosis code
by using the MUT-IIor disconnect the negative battery
cable from the battery terminal and then leave it for at
least ten seconds. After that, reconnect the battery cable,
and then let the engine run at idle for approximately 10
minutes.
BASIC IDLE SPEED ADJUSTMENT
NOTE
(1) The basic idling speed has been adjusted by the
speed adjusting screw by the manufacturer, and there
should usually be no need for readjustment.
(2) If the adjustment has been changed by mistake, the
idle speed may become too high or the idle speed
may drop too low when loads from components such
as the A/C are placed on the engine. If this occurs,
adjust by the following procedure.
(3) The adjustment, if made, should be made after first
confirming that the spark plugs, the injectors, the idle
speed control servo, the compression pressure, etc.,
are all normal.
1. Before inspection and adjustment, set the vehicle to the
pre-inspection condition.
2. Connect the MUT-IIto the diagnosis connector (16-pin).
NOTE
When the MUT-IIis connected, the diagnosis control
terminal should be earthed.
3. Start the engine and run at idle.
4. Select the item No. 30 of the MUT-IIActuator test.
NOTE
This holds the idle speed control servo at the basic step
to adjust the basic idle speed.
5. Check the basic idle speed.
Standard value: 850±100 r/min
NOTE
(1) The engine speed may be 20 to 100 r/min lower
than indicated above for a new vehicle [driven
approximately 500 km or less], but no adjustment
is necessary.
(2) If the engine stalls or the engine speed is low even
though the vehicle has been driven approximately
500 km or more, it is probable that deposits are
adhered to the throttle valve, so clean it. (Refer to
P.13A-126.)

MPI -On-vehicle Service13A-130
14. If any of fuel pressure measured in steps 10 to 13 is out of
specification, troubleshoot and repair according to the
table below.
SymptomProbable causeRemedy
DFuel pressure too low
DFuelpressuredropsafterracing
Clogged fuel filterReplace fuel filter
DFuelpressuredrops after racing
DNo fuel pressure in fuel return
hose
Fuel leaking to return side due to poor
fuel regulator valve seating or settled
springReplace fuel pressure regulator
Low fuel pump delivery pressureReplace fuel pump
Fuel pressure too highBinding valve in fuel pressure
regulatorReplace fuel pressure regulator
Clogged fuel return hose or pipeClean or replace hose or pipe
Same fuel pressure when vacuum
hose is connected and when
disconnected
Damaged vacuum hose or clogged
nippleReplace vacuum hose or clean nipple
disconnectedFuel pressure control system
malfunctionCheck the fuel pressure control
system
15. Stop the engine and check change of fuel pressure gauge
reading. Normal if the reading does not drop within 2
minutes. If it does, observe the rate of drop and
troubleshoot and repair according to the table below.
SymptomProbable causeRemedy
Fuel pressure drops gradually after
engineisstopped
Leaky injectorReplace injector
engineisstopped
Leaky fuel regulator valve seatReplace fuel pressure regulator
Fuel pressure drops sharply
immediately after engine is stoppedCheck valve in fuel pump is held openReplace fuel pump
16. Release residual pressure from the fuel pipe line.
(Refer to P.13A-125.)
17. Remove the fuel pressure gauge and special tool from
the delivery pipe.
Caution
Cover the hose connection with rags to prevent splash
of fuel that could be caused by some residual pressure
in the fuel pipe line.
18. Replace the O-ring at the end of the fuel high pressure
hose with a new one. Furthermore, apply engine oil to
the new O-ring before replacement.
19. Fit the fuel high pressure hose over the delivery pipe
and tighten the bolt to specified torque.
Tightening torque: 5.0±1.0 N·m
20. Check for any fuel leaks by following the procedure in
step 7.
21. Disconnect the MUT-II.

MPI -On-vehicle Service13A-131
COMPONENT LOCATION
NameSymbolNameSymbol
A/C relayJFuel pump relay 1, 2Q
A/C switchTFuel pump relay 3H
Air flow sensor (integrated intake air tempera-
ture sensor and barometric pressure sensor)OFuel pump resistorH
Camshaft position sensorNIdle speed control servo (stepper motor)G
Crank angle sensorKIgnition coil (integrated power transister)M
Detonation sensorEInjectorC
Diagnosis connectorSOxygen sensor (front)L
EGR control solenoid valveDOxygen sensor (rear)X
Engine control relayIPower steering fluid pressure switchA
Engine coolant temperature sensorNResistor (for injector)H
Engine warning lamp (check engine lamp)RSecondary air control solenoid valveD
Engine-ECUUThrottle position sensorG
Fan motor relayJVehicle speed sensorF
Fuel pressure control solenoid valveBWaste gate solenoid valveP
ABCDEFGHIJK
LMNOP
QRSTU