Mitsubishi Eclipse. Manual — part 561

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-787

.

CIRCUIT OPERATION

• The idle air control motor power is supplied from

the MFI relay (terminal 4).

• The ECM (terminals 14, 15, 28, 29) <M/T> or

PCM (terminals 14, 15, 28, 29) <A/T> drives the
stepper motor by sequentially turning "ON" the
power transistors in the ECM <M/T> or PCM
<A/T> and providing ground to the idle air control
motor (terminals 1, 3, 4, 6).

.

TECHNICAL DESCRIPTION

• The amount of air taken in during idling is regu-

lated by the opening and closing of the servo
valve located in the air passage that bypasses
the throttle body.

• If there is a malfunction of the IAC system, the

actual engine speed will not be identical to the
target engine speed.

• The ECM <M/T> or PCM <A/T> checks the differ-

ence between the actual engine speed and the
target engine speed.

.

DESCRIPTIONS OF MONITOR METHODS
Difference between actual and target idle speed is

over the specified value.

.

MONITOR EXECUTION
Continuous

.

MONITOR EXECUTION CONDITIONS (Other
monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Misfire monitor

• Exhaust gas recirculation (EGR) system monitor

• Fuel system monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.

AK300084

IDLE AIR
CONTROL
MOTOR

CONNECTOR: B-34

AB

B-34 (B)

AK300121

MFI RELAY

CONNECTOR: A-18X

AB

A-18X

AK300091

CONNECTOR: C-51 <M/T>

ECM

AF

C-51 (GR)

AK300244

CONNECTOR: C-52 <A/T>

AC

PCM

C-52 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-788

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Under the closed loop idle speed control.

• The engine coolant temperature is more than

approximately 77

°C (171°F).

• Battery positive voltage is higher than 10 volts.

• Power steering pressure switch: "OFF".

• Volumetric efficiency is lower than 40 percent.

• Barometric pressure is higher than 76 kPa (22.4

in.Hg).

• Intake air temperature is higher than −10°C

(14

°F).

• 60 seconds have elapsed from the start of the

previous monitoring.

• Target idle air control motor position is more than

100 steps.

Judgment Criteria

• The actual idle speed is more than 100 r/min

lower than the target idle speed for 12 seconds.

.

OBD-ll DRIVE CYCLE PATTERN
Refer to , Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 6

− Other Monitor

P.13B-7

.

.

TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )

• Idle air control motor failed.

• Open or shorted idle air control motor circuit, or

harness damage, or connector damage.

• ECM failed. <M/T>

• PCM failed. <A/T>

• Throttle valve area is dirty.

END

NO

NO

NO

YES

YES

YES

MALFUNCTION

GOOD

START

CALCULATE

Ne

MONITORING

CONDITIONS

Ne = (ACTUAL-Ne) - (TARGET-Ne)

Ne: ENGINE SPEED

Ne < -100 r/min OR

> 200 r/min

HAVE 10secs PASSED?

AK204002

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-789

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MB991709: Test Harness

STEP 1. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958, read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P0506 set?

YES : Refer to Diagnostic Trouble Code Chart

P.13B-23

.

NO : Go to Step 2.

STEP 2. Check the throttle body (throttle valve area).
Q: Is the throttle valve area dirty?

YES : Perform cleaning. Refer to Throttle body (throttle

valve area) cleaning

P.13B-1102

. Then go to Step 14.

NO : Go to Step 3.

STEP 3. Check connector B-34 at idle air control motor for
damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 14.

AK300810

AB

MB991911

16-PIN

MB991827

MB991824

AK300438

1

2

3

4

5

6

CONNECTOR: B-34

AB

B-34 (B)

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-790

STEP 4. Check the idle air control motor coil resistance.
(1) Disconnect the idle air control motor connector B-34.

(2) Measure the resistance between idle air control motor

connector terminal No. 2 and either terminal No. 1 or
terminal 3.

Standard value: 28

− 33 ohms [at 20°C (68°F)]

(3) Measure the resistance between idle air control motor

connector terminal No. 5 and either terminal No. 4 or
terminal No. 6.

Standard value: 28

− 33 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 28 and 33 ohms?

YES : Go to Step 5.
NO : Replace the idle air control motor. Then go to Step 14.

AK300438

1

2

3

4

5

6

CONNECTOR: B-34

AB

B-34 (B)

HARNESS CONNECTOR:
COMPONENT SIDE

AKX01561

1 2 3
4 5 6

1 2 3
4 5 6

AB