Mitsubishi Montero Sport (2004+). Manual - part 307

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-641

.

CIRCUIT OPERATION

• The idle air control (IAC) motor power is supplied 

from the MFI relay (terminal No. 1).

• The PCM (terminals No. 14, No. 15, No. 28, No. 

29) drives the stepper motor by sequentially turn-
ing "ON" the power transistors in the PCM and 
providing ground to the idle air control motor (ter-
minals No. 1, No. 3, No. 4, No. 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 PCM checks the difference 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

.

AK200029 AB

CONNECTOR: A-40

IDLE AIR CONTROL MOTOR

A-40(B)

AK201000

MFI RELAY

CONNECTOR: C-59

AB

C-59

AK103911AB

CONNECTOR: C-14

C-14

AK103738AD

CONNECTOR: C-89

PCM

C-89(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-642

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Under the closed loop idle speed control.

• Engine coolant temperature is more than approx-

imately 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-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13A-4

.

.

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, har-

ness damage or connector damage.

• Throttle valve area is dirty.

• PCM failed.

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)

13A-643

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 other than P0506 set?

YES : Refer to Diagnostic Trouble Code Chart 

P.13A-26

.

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 On-vehicle Service 

− 

Throttle body (throttle valve area) cleaning 

P.13A-881

. Then go to Step 14.

NO :  Go to Step 3.

AK303629AB

MB991911

MB991827

MB991824 

16-PIN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-644

STEP 3. Check connector A-40 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.

STEP 4. Measure the idle air control motor coil resistance.
(1) Disconnect the idle air control motor connector A-40.
(2) Measure the resistance between idle air control motor 

connector terminal No. 2 and either terminal No. 1 or 
terminal No. 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 [at 

20

°C (68°F)]?

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

AK200476

1

2

3

4

5

6

AB

CONNECTOR: A-40

A-40(B)

HARNESS 
CONNECTOR: 
COMPONENT 
SIDE

AK200476

1

2

3

4

5

6

AB

CONNECTOR: A-40

A-40(B)

HARNESS 
CONNECTOR: 
COMPONENT 
SIDE

AKX01561

1 2 3
4 5 6

1 2 3
4 5 6

AB