Content .. 97 98 99 100 ..

Mitsubishi Colt Ralliart. Manual - part 99

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-350

INJECTOR
Measurement Method

1. Disconnect the injector connector, and then

connect the special tool Test harness set
(MB991658) in between (All terminals should be
connected).

2. Connect the oscilloscope special patterns pickup

to terminal No. 2 of the injector connector.

Alternate Method (Test harness not
available)

1. Disconnect the engine-ECU connector or

engine-CVT-ECU connector and connect the
special tool Power plant ECU check harness
(MB991987) in between.

2. Connect the oscilloscope special patterns pickup

to engine-ECU <M/T> or engine-CVT-ECU
<CVT> terminal No. 8 (When checking the No. 1
cylinder).

3. Connect the oscilloscope special patterns pickup

to engine-ECU <M/T> or engine-CVT-ECU
<CVT> terminal No. 9 (When checking the No. 2
cylinder).

4. Connect the oscilloscope special patterns pickup

to engine-ECU <M/T> or engine-CVT-ECU
<CVT> terminal No. 23 (When checking the No. 3
cylinder).

5. Connect the oscilloscope special patterns pickup

to engine-ECU <M/T> or engine-CVT-ECU
<CVT> terminal No. 24 (When checking the No. 4
cylinder).

Standard Wave Pattern

Observation conditions

AK101807

Special
patterns
pickup

Oscilloscope

Function

Special patterns

Pattern height

Variable

Variable knob

Adjust while viewing the
wave pattern

Pattern selector

Display

Engine

Idle

AK305803

(V)

Power
voltage

Solenoid back
electromotive force
(Approximately 7×10V)

Drive signal: ON

Drive signal: OFF

Point B
Injector drive
time

Point A.

Standard wave pattern

Time

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-351

Wave Pattern Observation Points

Point A: Height of solenoid back electromotive force

Point B: Injector drive time

•

The injector drive time will be synchronized with the

M.U.T.-III tester display.

• When the engine is suddenly raced, the drive

time will be greatly extended at first, but the drive
time will soon match the engine speed.

IGNITION COIL AND POWER TRANSIS-
TOR
Measurement Method

1. Disconnect the ignition coil connector, and

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

2. Connect the oscilloscope special patterns pickup

to terminal No. 3 of each ignition coil connector in
turn.

Alternate Method (Test harness not
available)

1. Disconnect the engine-ECU connector or

engine-CVT-ECU connector and connect the
special tool Power plant ECU check harness
(MB991987) in between.

2. Connect the oscilloscope probe to engine-ECU

<M/T> or engine-CVT-ECU <CVT> terminal No.
10. (When checking the No. 1 cylinder.)

3. Connect the oscilloscope probe to engine-ECU

<M/T> or engine-CVT-ECU <CVT> terminal No.
25. (When checking the No. 2 cylinder.)

4. Connect the oscilloscope probe to engine-ECU

<M/T> or engine-CVT-ECU <CVT> terminal No.
40. (When checking the No. 3 cylinder.)

5. Connect the oscilloscope probe to engine-ECU

<M/T> or engine-CVT-ECU <CVT> terminal No.
55. (When checking the No. 4 cylinder.)

Contrast with standard wave
pattern

Probable
cause

Solenoid coil back electromotive
force is low or doesn’t appear at
all.

Short in the
injector solenoid

AKX01605AE

When idling
When racing

AK300345

1 2 3

Special
patterns
pickup

Oscilloscope

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-352

Standard Wave Pattern

Observation condition

Wave Pattern Observation Points

Point: When the engine speed increases, verify that
the power transistor control signal (ignition timing)
advances.

Examples of Abnormal Wave Patterns

•

Example
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 V
too low.

Function

Special patterns

Pattern height

Low

Pattern selector

Display

Engine

Idle

AK204112

Standard wave pattern

Crank angle
sensor output
wave pattern

Power transistor
control signal
wave pattern

TDC: Top dead centre

2 engine revolutions
(1 camshaft revolution)

Ignition timing

Dwell section

OFF

5˚ BTDC

(V)

TDC

AK203246

Normal wave pattern

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-353

EGR VALVE (STEPPER MOTOR) <CVT>
Measurement Method

1. Disconnect the EGR valve connector, and con-

nect the special tool test harness (MB991658) in
between.

2. Connect the oscilloscope probe to the EGR

valve-side connector terminal 1, terminal 3, termi-
nal 4 and terminal 6 respectively.

Alternate Method (Test Harness not
Available)

1. Disconnect the engine-CVT-ECU connector and

connect the special tool Power plant ECU check
harness (MB991987) in between.

2. Connect the oscilloscope probe to

engine-CVT-ECU terminal No. 5, connection
terminal No. 6, connection terminal No. 53, and
connection terminal No. 54 respectively.

Standard Wave Pattern

Observation condition

Wave pattern Observation Points

Check that the standard wave pattern appears when
the EGR control servo is operating.
Point A: Presence or absence of induced electromo-
tive force from the motor turning. (Refer to the abnor-
mal wave pattern.)

Point B: Height of coil reverse electromotive force

AK303311

1 2 3
4 5 6

Special
patterns
pickup

Oscilloscope

Function

Special patterns

Pattern height

High

Pattern selector

Display

Engine

Ignition switch: OFF

→

AK301251

Standard wave pattern

Stepper motor
control signal
wave pattern

Motor coil energizing time

Point A
Induced electromotive
force from the motor
turning

Point B
Coil reverse electromotive
force (Approximately 40 V)

(V)

Time

Contrast with standard wave
pattern

Probable
cause

Induced electromotive force does
not appear or is extremely small.

Motor is
malfunctioning

Contrast with standard wave
pattern

Probable
cause

Coil reverse electromotive force
does not appear or is extremely
small.

Short in the
coil

Main

Index

Group

TOC

Content .. 97 98 99 100 ..