Mitsubishi 380. Manual - part 641

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-656

Point B: Injector drive time

1. The injector drive time should be synchronized with the 

diagnostic tool 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.

IGNITION COIL AND IGNITION POWER 
TRANSISTOR

Required Special Tools:

• MB992044: ECU Check Harness

.

Measurement Method

1. Disconnect the all ECU connectors, and connect check har-

ness special tool (MB992044) between the separated con-
nectors.

2. Connect the oscilloscope probe to each check harness con-

nector terminal to analyze each cylinder:

• Terminal No. 151 for the number 1 cylinder.

• Terminal No. 150 for the number 2 cylinder.

• Terminal No. 144 for the number 3 cylinder.

• Terminal No. 148 for the number 4 cylinder.

• Terminal No. 143 for the number 5 cylinder.

• Terminal No. 134 for the number 6 cylinder.

Standard Wave Pattern

AKX01605

WHEN IDLING

WHEN RACING

AB

Observation condition

Function

Special pattern

Pattern height

Low

Pattern selector

Display

Engine r/min

Idle speed

03DB246A

OSCILLOSCOPE

POWER PLANT ECU

CHECK HARNESS

CONNECTOR

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-657

Wave Pattern Observation Points
Point: The power transistor control signal (ignition timing) is 

advanced when the engine speed is increased.

.

Examples of Abnormal Wave Patterns

Example 1 (Wave pattern during engine cranking)

• Cause of problem

Open-circuit in ignition primary circuit

• Wave pattern characteristics

Voltage value is too low.

CONDITION OF WAVE 
PATTERN BUILD-UP 
SECTION AND MAXIMUM 
VOLTAGE

PROBABLE CAUSE

Voltage value is too low

Open-circuit in ignition primary 
circuit

AK203308

TDC

5˚BTDC

ON

TIME

AC

OFF

CRANKSHAFT

POSITION 

SENSOR OUTPUT

WAVE PATTERN

IGNITION POWER 

TRANSISTOR 

CONTROL SIGNAL 

WAVE PATTERN

Standard wave pattern

IGNITION

TIMING

DWELL 

SECTION

5

10

0

0

2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)

(VOLT)

AK203246

NORMAL WAVE

PATTERN

AC

SPECIAL TOOLS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-658

SPECIAL TOOLS

M1131000601293

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

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 Measurement 
Adapter
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.

MB992044
ECU check harness

MD998478-01

• lnspection using an 

oscilloscope

• lnspection of the 

electronic control unit 
(ECU) terminal voltage 
check

MB991910

MB991826

MB991958

MB991911

MB991914

MB991824

MB991827

MB991825

DO NOT USE

A

B

C

D

E

F

G

DO NOT USE

SPECIAL TOOLS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-659

MD998478
Test harness (3 pin, 
triangle)

MD998478-01

• Inspection using an 

oscilloscope

MB991637
Fuel pressure gauge set

Tool not available

• Measurement of fuel 

pressure

TBA
Adaptor hose

Measurement of fuel 
pressure

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

MB991637

03DB257A