Mitsubishi Galant 9G. Manual - part 917

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-1110

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.

EGR VALVE (STEPPER MOTOR)

Required Special Tools:

• MB991658: Test Harness

• MB991923: Power Plant ECU Check Harness

.

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) <2.4L ENGINE>

13A-1111

Measurement Method

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

harness special tool (MB991658) between the separated 
connector (All terminals should be connected).

2. Connect the oscilloscope probe to the EGR valve connector 

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

.

Alternate method (Measure at the PCM)

1. Disconnect the all PCM connectors, and connect check 

harness special tool (MB991923) between the separated 
connectors.

2. Connect the oscilloscope probe to check harness terminal 

No. 124, No. 130, No. 136 and No. 142.

Standard Wave Pattern

AK203303

1

2 3

4

5 6

EGR VALVE
CONNECTOR

OSCILLOSCOPE

MB991658

AB

Observation condition

Function

Special pattern

Pattern height

High

Pattern selector

Display

Engine condition

Revving

AK202954

127 126 125 124 123 122 121

133 132 131 130 129 128

140 139 138 137 136 135 134

146 145 144 143 142 141

153 152 151 150 149 148 147

AB

POWER PLANT ECU 
CHECK HARNESS CONNECTOR

MB991923

PCM

AK203304

127 126 125 124 123 122 121

133 132 131 130 129 128

140 139 138 137 136 135 134

146 145 144 143 142 141

153 152 151 150 149 148 147

AB

OSCILLOSCOPE

POWER PLANT ECU
CHECK HARNESS
CONNECTOR

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-1112

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.)

Point B: Height of coil back electromotive force

.

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Induced electromotive force 
does not appear or is 
extremely small

Malfunction of motor

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Coil reverse electromotive 
force does not appear or is 
extremely small

Short in the coil

AKX01607 AC

(V)

30

20

10

0

EGR VALVE
(STEPPER 
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) <2.4L ENGINE>

13A-1113

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 Tools:

• MB991658: Test Harness

• MB991923: Power Plant ECU Check Harness

.

Measurement Method

1. Disconnect the intermediate connector B-32, and connect 

the test harness special tool (MB991658) between the sep-
arated connector.

2. Connect the oscilloscope probe to each intermediate con-

nector B-32 terminal to analyze each cylinder:

• Terminal No. 2 for the number 1 cylinder.

• Terminal No. 7 for the number 3 cylinder.

• Terminal No. 6 for the number 5 cylinder.

<Measure at the left bank (number 2, 4, 6 cylinders)>

1. Disconnect the ignition coil connector, and connect test har-

ness special tool (MB991348) between the separated con-
nector. (All terminals should be connected.)

2. Connect the oscilloscope probe to ignition coil connector 

terminal No. 3.

.

AKX01608 AB

AKX01609

OPEN
CIRCUIT
SIDE

NORMAL
SIDE

AB

AK401067

1 2 3

IGNITION COIL
CONNECTOR

OSCILLOSCOPE

MB991658

AB