1991 MITSUBISHI ECLIPSE sensor

14-72FUEL SYSTEM - MPI Svstem InsDection <2.0L DOHC Engine>
MALFUNCTION INDICATOR LIGHTAmong the self-diagnosis items, a malfunction indicator light
comes on to notify the driver of the emission control items
when an irregularity is detected.
However, when an irregular signal returns to normal and the
engine control unit judges that it has returned to normal. the
malfunction indicator light goes out.
Moreover, when the ignition switch is turned off, the light goes
out. Even if the ignition switch is turned on again, the light doesnot come on until the irregularity is detected.
Here, immediately after the ignition switch is turn on, the
malfunction indicator light is lit for 5 seconds to indicate that
the malfunction indicator light operates normally.
I--l
klfunctionindicator light
Items indicated by the lightening malfunction light
Engine control unit
Oxygen sensor
Air flow sensor
Intake air temperature sensor
Throttle positron sensor
Engrne coolant temperature sensor
Crank angle sensor
Top dead center sensor
Barometric pressure sensor
Detonatron sensor
Injector
Fuel pump
EGR
Ignition co11
/
iMALFUNCTION INDICATOR LIGHT INSPECTION
When turning on the ignition switch, check that the light comes
on.
NOTEIf the light does not come on, check the harness and light for
breakage.

FUEL SYSTEM - MPI System Inspection <2.0L DOHC Engine>
SELF-DIAGNOSIS14-73
N14PAAEThe engine control unit monitors the input/output signals
(some signals at all times and the others under specified
conditions) of the engine control unit.
When it is noticed that an irregularity has continued for a
specified time or longer from when the irregular signal is
initially monitored. Passing a certain number, the engine
control unit judges that an irregularity has occurred, memorizesthe malfunction code, and outputs the signal to the
self-diagnosis output terminal.
There are 14 diagnosis items, and the diagnosis results can beread out with a voltmeter.
Moreover, since memorization of the malfunction codes is
backed up directly by the battery, the diagnosis results are
memorized even if the ignition key is turned off. The malfunc-
tion codes will, however, be erased when the battery terminal
or the engine control unit connector is disconnected.
CautionIf the sensor connector is disconnected with the ignition
switch turned on, the malfunction code is memorized. In
this case, disconnect the battery terminal
(-) for 10seconds or more, and the diagnosis memory will be
erased.The 14 diagnosis items are provided as follows, and if plural
items are activated, they are all indicated sequentially from thesmallest code number.
arometnc pressure sensor
CHECK PROCEDURE (SELF-DIAGNOSIS)Precautions for OperationN14PCAE2(1) When battery voltage is low, no detection of failure is
possible. Be sure to check the battery for voltage and otherconditions before starting the test.
(2) Diagnosis item is erased if the battery or the engine controlunit connector is disconnected. Do not disconnect the
battery before the diagnosis result is completely read.
(3) After check and correction are over, disconnect ground
cable for 10 seconds or more from negative terminal of
battery and connect it again to make sure that failure code
is erased.

FUEL SYSTEM- MPI Svstem InsDection <2.0L DOHC Engine>
MPI
diagnosis
I Ground
INSPECTION PROCEDURE - USING VOLTMETERN14PCAGZ
(1) Connect an analogue voltmeter to the self-diagnosis con-
nector.(2) Turn ignition switch to ON, and indication of engine control
unit memory contents will immediately start. If the system
is in normal condition, pointer of voltmeter indicates normalpattern. If any abnormality is in memory, the pointer of
voltmeter will deflect, indicating abnormal item as de-
scribed in “Diagnosis Chart”.
After recording the abnormal item, check and repair each
part according to the check items in “Diagnosis Chart”.
(3) If the defective parts have been repaired, disconnect the
negative terminal of battery cable for
10 seconds or more
and connect it again to make sure that the abnormal code
has been erased.
DIAGNOSIS CHART (FAULT TREE)NlQPRADoutputDiagnosis codeIreference
Dragnosrs Item- Check item (Remedy)
orderOutput signal patternNo.Memory
1Engine controlunit- - W$$ace engine control: I
12A0104
2Oxygen sensor11Retainedl Harness and connector:-J-l-J-0 Oxygen sensor
o Fuel pressure
0 Injectors(Replace if defective)
12A0104l Intake air leaks
3Air flow sensor
:-rLJL ‘*
Retainedl Harness and connector
(If harness and connector
are normal, replace airflow sensor assembly.)
12A0104
4Intake au
J--lNlL l3
Retarnedl Harness and connectortemperature sensor Hl Intake air temperature
sensor
12A0104
5Throttle postron
:n l4
Retainedl Harness and connector
sensorl Throttle position sensorl Idle position switch
17A0104
6Engine coolant
:nn 2’
Retainedl Harness and connectortemperature sensorl Engine coolant temper-
ature sensor
12A0107

FUEL SYSTEM - MPI Svstem InsDection <2.0L DOHC Engine>
outputDiagnosis codeIreferenceDragnosrs ItemCheck item (Remedy)orderOutput signal patternNo.Memory
7Crank angle sensor
:nn **
Retainedl Harness and connector
(If harness and connector
are normal, replace crank
angle sensor assembly.)
12A0107
8Top dead center
:- 23
Retainedl Harness and connectorsensor (No.1 and(If harness and connector
No. 4 cylinder)are normal, replace crank
angle sensor assembly.)
12A0107
9Vehicle speed sensor24Retainedl Harness and connector
(reed swatch)H
I u I nlvln
l Vehicle speed sensor
(reed switch)
L12A0107
10Barometnc pressure25Retainedl Harness and connector
sensorH(If harness and connector
are normal, replace
LULllnMllbarometric pressure
12A0107sensor assembly.)
11Detonation sensorRetainedl Harness and connector
:m 31
l Detonation sensor
12R0468
12Injector
:m 41
Retainedl Harness and connector0 Injector coil resistance
12A0105
13Fuel pump42Retainedl Harness and connectorH
UUUI nn
0 Control relay
L12A0105
14EGR 43Retainedl Harness and connector
Hl EGR temperature sensor
u u u I nnn
l EGRvalvel EGR valve control sole-Lnoid valve
12A0105l EGR valve control vacuum
15Ignition coil44Retainedl Harness and connectorH
UUUL-llMlL
0 Ignition coil0 Power transistor
L12A0105
16Normal state---H
L
12A0104
NOTEReplace the engine control unit if a malfunction code is output although the inspection reveals that there is no problem with the check
items.

14-76FUEL SYSTEM - MPI Svstem InsDection <2.0L DOHC Enaine>

Air flow sensorsrde connector
6FUO622
6FUO623
16Rl251
INTAKE AIR TEMPERATURE SENSOR
INSPECTION
Nl4OHAB
(1) Disconnect the air flow sensor connectors.
(2) Measure resistance between terminals
@ and @I Turbo>
(3) Measure resistance between terminals @and @I
Temperature “C (“F)Resistance kR
0 (32)6.0
20
(68)2.7
80 (176)
0.4(4) Measure resistance while heating the sensor using a hair
drier.
Temperature “C (“F)
Higher
Resistance k0
Smaller(5) If the value deviates from the standard value or the
resistance remains unchanged, replace the air flow sensor
assembly.
ENGINE COOLANT TEMPERATURE SENSOR
NlMABEl
INSPECTION
(1) Remove engine coolant temperature sensor from the
intake manifold.
(2) With temperature sensing portion of engine coolant
temperature sensor immersed in hot water, check resist-
ance.
Temperature
“C (“F)
0 (32)
Resistance kfl
5.9
20 (68)2.5
40 (I 04)2.7
80
(I 76)0.3
(3) If the resistance deviates from the standard value greatly,
replace the sensor.

FUEL SYSTEM - MPI Svstem InsDection <2.0L DOHC Engine>14-77INSTALLATION
(1) Apply specified sealant to threaded portion and tighten to
specified torque.
Specified sealant: MOPAR Part No.4318034 or
equivalent
Specified torque: 20
- 40 Nm (15 - 29 ft.lbs.1(2) Fasten harness connectors securely.
THROTTLE POSITION SENSOR
INSPECTION
N14QBBKl(1) Disconnect the throttle position sensor connector.
(2) Measure resistance between terminal
@I (sensor ground)
and terminal
@ (sensor power).
Standard value: 3.5
- 6.5 kR(3) Connect a pointer type ohmmeter between terminal
@I(sensor ground) and terminal
@ (sensor output).
(4) Operate the throttle valve slowly from the idle position to
the full open position and check that the resistance changessmoothly in proportion with the throttle valve opening
angle.
6FU1244(5) If the resistance is out of specification, or fails to change
smoothly, replace the throttle position sensor.
Throttle position sensor installation torque:
1.5
- 2.5 Nm (1.1 - 1.8 ft.lbs.)
J II\/ hFU1419IDLE POSITION SWITCH
INSPECTION
N14QKAEa(1) Keeping the acceleration pedal released, check that the
throttle valve lever or the idle position switch is pushed.
NOTEIf it is not pushed, adjust the idle position switch (fixed
speed adjusting screw). (Refer to
P.14-52.)(2) Disconnect the idle position switch connector.
(3) Check the continuity between terminal
@) to the ground.

FUEL SYSTEM - MPI System Inspection <2.0L DOHC Engine>
6FUO999
Accelerator pedal
DepressedContinuity .
Non-conductive
(03 fl)
ReleasedIConductive (0 fl)I(4) Replace the idle position switch if faulty.
NOTE
For replacement procedure, refer to the idle position switch(fixed speed adjusting screw) adjustment section
(P.14-
52.).OXYGEN SENSOR
NllQDeJ
INSPECTION(1) Disconnect the oxygen sensor connector.
(2) Check that there is continuity [approx. 12
52 at 20°C (68”F)l
between oxygen sensor connector terminal @ and terminal
GO.(3) If there is no continuity, replace the oxygen sensor.
(4) Warm up the engine until the engine coolant temperature
exceeds
80°C (176°F).(5) Use jumper wires to connect oxygen sensor terminal
@and terminal
@ to the battery @ terminal and 0 terminal.
Caution
Be very careful when connecting the jumper wires
because the oxygen sensor will be damaged if a
mistake is made in the connecting terminals.
(6) Connect a digital voltmeter between terminal
@ and
terminal
0.(7) While repeatedly racing the engine, measure the ‘output
voltage of the oxygen sensor.
When racing
engineWhen the
air/fuel mixture raticINSTALLATION
1. For removal and installation of oxygen sensor, refer to
GROUP 11
- Exhaust Manifold.
2. Oxygen sensor tighten to specified torque.
Specified torque: 40
- 50 Nm (29 - 36 ft.lbs.)

FUEL SYSTEM - MPI System Inspection <2.0L QOHC Engine>14-79EGR TEMPERATURE SENSOR
N14RCHAaRefer to GROUP 25
- Exhaust Gas Recirculation System.
VEHICLE SPEED SENSOR
Refer to GROUP 8
- Meters and Gauges.
N140EBBaAIR CONDITIONER SWITCH
Nl4QQAEaRefer to GROUP 8
- Column Switch.
POWER STEERING OIL PRESSURE SWITCH
N14RCJBRefer to GROUP 19 for power steering system inspection.
INJECTORS
NWXAHCHECKING OPERATION SOUND
Using a sound-scope, check the operation sound (“chi-chi-chi”)of the injectors during idling or during cranking.
Check to be sure that the operation sound increases when the
engine speed is increased.
Caution
Note that the sounds of other injectors may be heard even
though the injector being checked is not operating, so caremust be taken when checking.
NOTEIf the operation sounds cannot be heard, check the injector
activation circuit.
If this circuit is normal, there is probably a malfunction of the
injector or of the engine control unit.
MEASURING OF RESISTANCE BETWEEN TERMINALS
(1) Disconnect the connector for the injectors.
(2) Measure the resistance between terminals.
Standard value:
13
-16 S2 [at 20°C (68”F)]2
- 3 52 [at 20% (68”F)]
(3) Connect the connector for the injectors.
IDLE SPEED CONTROL SERVO
N14QUADCHECKING OPERATING SOUND
(1) Check that when the ignition switch is placed in the ON
position (the engine not started), the operating sound of thestepper motor can be heard over the idle speed control
servo.
(2) If no operating sound can be heard, check the stepper
motor drive circuit.
(If the circuit is good, a defective stepper motor or engine
control unit is suspected.)