Mitsubishi Montero (2004+). Manual - part 373

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-979

INJECTOR

Required Special Tool:

• MD998474: Test Harness

.

Measurement Method
1. Disconnect the injector intermediate connector, and connect 

the test harness special tool (MD998474) in between.

2. Connect the oscilloscope probe to each injector 

intermediate connector terminal to analyze each cylinder:

• Terminal No. 3 (green clip of special tool) for the number 1 

cylinder

• Terminal No. 2 (white clip) for the number 2 cylinder 

• Terminal No. 1 (blue clip) for the number 3 cylinder

• Terminal No. 7 (yellow clip) for the number 4 cylinder

• Terminal No. 6 (red clip) for the number 5 cylinder

• Terminal No. 5 (black clip) for the number 6 cylinder

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 1. 

(When checking the number 1 cylinder.)

2. Connect the oscilloscope probe to PCM terminalNo.  5. 

(When checking the number 2 cylinder.)

3. Connect the oscilloscope probe to PCM terminal No. 14. 

(When checking the number 3 cylinder.)

4. Connect the oscilloscope probe to PCM terminal No. 21. 

(When checking the number 4 cylinder.)

5. Connect the oscilloscope probe to PCM terminal No. 2. 

(When checking the number 5 cylinder.)

6. Connect the oscilloscope probe to PCM terminal No. 6. 

(When checking the number 6 cylinder.)

Standard Wave Pattern

Observation conditions

Function

Special pattern

Pattern height

Variable

Variable knob

Adjust while viewing the 
wave pattern

Pattern selector

Display

Engine r/min

Idle speed

AK102982 AB

OSCILLOSCOPE

INJECTOR
INTERMEDIATE
CONNECTOR

MD998474

1 2 3 4

5 6 7 8

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-980

Wave Pattern Observation Points
Point A: Height of injector coil induced voltage.

Point B: Injector drive time

1. The injector drive time should be synchronized with the 

scan tool tester display.

2. When the engine is suddenly revved, the drive time will 

be greatly extended at first, but the drive time will soon 
return to original length.

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Injector coil induced voltage is 
low or doesn't appear at all

Short in the injector solenoid

AKX01604

(V)

50

0

DRIVE SIGNAL:"ON"

POINT B:
INJECTOR DRIVE 
TIME

POINT A

DRIVE SIGNAL:"OFF"

POWER VOLTAGE

INJECTION COIL INDUCED
VOLTAGE (APPROXIMATELY 50-60 V)

AB

Standard wave pattern

AKX01605

WHEN IDLING

WHEN RACING

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-981

EGR VALVE (STEPPER MOTOR)

Required Special Tool:

• MB991658: Test Harness

.

Measurement Method
1. Disconnect the EGR valve connector, and connect the test 

harness special tool (MB991658) in between. (All terminals 
should be connected.) 

2. Connect the oscilloscope probe to the EGR valve connector 

terminal No. 1, terminal No. 3, terminal No.  4, No. terminal 6 
respectively.

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminals No. 3, No. 

12, No. 19 and No. 26.

Standard Wave Pattern

Wave Pattern Observation Points

1. Check that the standard wave pattern appears when the 

EGR valve is operating.

Point A: Presence or absence of induced electromotive force 

from the motor turning. (Refer to abnormal wave pattern.)

Observation condition

Function

Special pattern

Pattern height

High

Pattern selector

Display

Engine condition

Racing

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Induced electromotive force 
does not appear or is 
extremely small

Malfunction of motor

AK201315

1 2 3
4 5 6

EGR VALVE
CONNECTOR

OSCILLOSCOPE

MB991658

AB

AKX01607 AB

(V)

30

20

10

0

IAC
MOTOR
CONTROL
SIGNAL
WAVE
PATTERN

THE WAVE PATTERN
APPEARS FOR AN
INSTANT, BUT SOON
DISAPPEARS.

POINT B COIL RE-
VERSE ELECTRO-
MOTIVE FORCE
(APPROXIMATELY
3 x10 V)

POINT AN INDUCED
ELECTROMOTIVE
FORCE FROM THE
MOTOR TURNING

TIME

Standard wave pattern

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-982

Point B: Height of coil back electromotive force

.

Examples of Abnormal Wave Patterns
Example 1
Cause of problem

• Malfunction of motor. (Motor is not operating.)

Wave pattern characteristics

• Induced electromotive force from the motor turning does 

not appear.

Example 2
Cause of problem

• Open circuit in the line between the EGR valve and the 

PCM.

Wave pattern characteristics

• Current is not supplied to the motor coil on the open cir-

cuit side. (Voltage does not drop to 0 volt.) Furthermore, 
the induced electromotive force wave pattern at the nor-
mal side is slightly different from the normal wave pat-
tern.

IGNITION COIL AND IGNITION POWER 
TRANSISTOR

Required Special Tool:

• MB991658: Test Harness Set

.

Measurement Method
1. Disconnect the ignition coil connector, and connect test 

harness special tool, MB991658, in between. (All terminals 
should be connected.)

2. Connect the oscilloscope probe to ignition coil connector 

terminal No. 3.

.

Alternate method (Test harness not available)
Connect the oscilloscope probe to PCM terminals No. 31 (for 

number 1 

− number 4), terminal No. 35 (for number 2 − 

number 5) , terminal No. 44 (for number 3 

− number 6) 

respectively.

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Coil reverse electromotive 
force does not appear or is 
extremely small

Short in the coil

AKX01608 AB

AKX01609

OPEN
CIRCUIT
SIDE

NORMAL
SIDE

AB

1

2

3

AK303226

IGNITION COIL
CONNECTOR

AK303226AB

MB996548

OSCILLOSCOPE