Mitsubishi Montero (2004+). Manual - part 374

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-983

Standard Wave Pattern

Wave Pattern Observation Points
Point: Condition of wave pattern build-up section and maximum 

voltage (Refer to abnormal wave pattern examples 1 and 2.

.

Observation condition

Function

Special pattern

Pattern height

Low

Pattern selector

Display

Engine r/min

Approximately 1,200 r/min

CONDITION OF WAVE 
PATTERN BUILD-UP 
SECTION AND MAXIMUM 
VOLTAGE

PROBABLE CAUSE

Rises from approximate 2 
volts to approximate 4.5 volts 
at the top-right

Normal

2-volt rectangular wave

Open-circuit in ignition primary 
circuit

Rectangular wave at power 
voltage

Ignition power transistor 
malfunction

(V)

6

4

2

0

6

4

2

0

AK201316

75˚BTDC

5˚BTDC

ON

TIME

T

AB

θ

T1

OFF

CRANKSHAFT
POSITION 
SENSOR OUTPUT
WAVE PATTERN

IGNITION POWER 
TRANSISTOR 
CONTROL SIGNAL 
WAVE PATTERN

Standard wave pattern

T:  REVOLUTION TIME CORRESPONDING

TO A CRANK ANGLE OF 180˚
COMPRESSION TOP DEAD CENTER

θ:  SPARK

ADVANCE
ANGLE

IGNITION PERIOD

DWELL 
SECTION

T1: TIME COMPUTED BY THE PCM

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-984

Examples of Abnormal Wave Patterns
Example 1 (Wave pattern during engine cranking)

• Cause of problem

Open-circuit in ignition primary circuit

• Wave pattern characteristics

Top-right part of the build-up section cannot be seen, and 
voltage value is approximately 2 volts too low.

Example 2 (Wave pattern during engine cranking)

• Cause of problem

Malfunction in ignition power transister

• Wave pattern characteristics

Power voltage results when the ignition power transistor is 
ON.

AKX01612

NORMAL WAVE
PATTERN

2V

AB

AKX01613

BATTERY
POSITION
VOLTAGE

NORMAL WAVE
PATTERN

AB

SPECIAL TOOLS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-985

SPECIAL TOOLS

M1131000600591

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

MB991958
A: MB991824
B: MB991827
C: MB991910
D: MB991911
E: MB991914
F: MB991825
G: MB991826
MUT-III sub assembly
A: Vehicle 
Communication Interface 
(V.C.I.)
B: MUT-III USB Cable
C: MUT-III Main Harness 
A (Vehicles with CAN 
communication system)
D: MUT-III Main Harness 
B (Vehicles without CAN 
communication system)
E: MUT-III Main Harness 
C (for Daimler Chrysler 
models only)
F: MUT-III Adapter 
Harness
G: MUT-III Trigger 
Harness

MB991824-KIT
NOTE: G: MB991826 
MUT-III Trigger Harness 
is not necessary when 
pushing V.C.I. ENTER 
key.

• Reading diagnostic 

trouble code

• MFl system inspection

• Measurement of fuel 

pressure

CAUTION

For vehicles with CAN 
communication, use 
MUT-III main harness A 
to send simulated 
vehicle speed. If you 
connect MUT-III main 
harness B instead, the 
CAN communication 
does not function 
correctly.

MB991658
Test harness set

Tool not available

• Inspection using an 

oscilloscope

• Adjustment of 

accelerator pedal 
position sensor

• Inspection of throttle 

position sensor

MB991910

MB991826

MB991958

MB991911

MB991914

MB991824

MB991827

MB991825

DO NOT USE

A

B

C

D

E

F

G

DO NOT USE

MB991658

SPECIAL TOOLS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-986

MB991709
Test harness set

MB991709-01

Inspection using an 
oscilloscope

MD998474
Test harness (8 pin, 
square)

MD998474-01

Inspection using an 
oscilloscope

MD998464
Test harness (4 pin, 
square)

MD998464-01

Inspection of heated 
oxygen sensor

MB991316
Test harness (4 pin, 
square)

Tool not available

Inspection of heated 
oxygen sensor

MD998478
Test harness (3 pin, 
triangle)

MD998478-01

Inspection using an 
oscilloscope

MB991637
Fuel pressure gauge set

Tool not available

Measurement of fuel 
pressure

MD998709
Adaptor hose

MIT210196

Measurement of fuel 
pressure

MD998742
Hose adaptor

MD998742-01

Measurement of fuel 
pressure

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

MB991637