Mitsubishi Galant (2004+). Manual - part 1356

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1117

Wave Pattern Observation Points

1. Check that cycle time becomes shorter when the engine 

speed increased.

.

Examples of Abnormal Wave Patterns
Example 1
Cause of problem

• Sensor interface malfunction.

Wave pattern characteristics

• Rectangular wave pattern is output even when the 

engine is not started.

Example 2
Cause of problem

• Loose timing belt.

• Abnormality in sensor disc.

Wave pattern characteristics

• Wave pattern is displaced to the left or right.

AK304079

AB

Standard wave pattern

CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN

CAMSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN

2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)

(VOLT)

5

0

5

0

No. 1TDC

No. 3TDC

No. 4TDC

No. 2TDC

(TIME)

TDC: TOP DEAD CENTER

AKX01597

AKX01602

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1118

INJECTOR

Required Special Tools:

• MB991658: Test Harness

• MB991923: Power Plant ECU Check Harness

.

Measurement Method
<Measure at the right bank (number 1, 3, 5 cylinders)>

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

the test harness special tool (MB991658) between the 
separated connector.

2. Connect the oscilloscope probe to each intermediate 

connector B-32 terminal to analyze each cylinder:

• Terminal No. 5 for the number 1 cylinder

• Terminal No. 10 for the number 3 cylinder

• Terminal No. 4 for the number 5 cylinder

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

1. Disconnect the injector connector, and connect the test har-

ness special tool (MB991658) between the separated con-
nector. (All terminals should be connected.)

2. Connect the oscilloscope probe to injector connector termi-

nal No. 2.

Alternate method (Measure at the PCM)

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

ness special tool (MB991923) between the separated con-
nectors.

1

2 3

6

7 8

4 5

9 10

AK203300

OSCILLOSCOPE

MB991658

B-32 INTERMEDIATE
CONNECTOR

AB

AK102980

1 2

INJECTOR
CONNECTOR

MB991658

AD

OSCILLOSCOPE

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1119

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

nector terminal to analyze each cylinder:

• Terminal No. 153 for the number 1 cylinder.

• Terminal No. 146 for the number 2 cylinder.

• Terminal No. 140 for the number 3 cylinder.

• Terminal No. 139 for the number 4 cylinder.

• Terminal No. 133 for the number 5 cylinder.

• Terminal No. 127 for the number 6 cylinder.

Standard Wave Pattern

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

Point B: Injector drive time

Observation conditions

Function

Special pattern

Pattern height

Variable

Variable knob

Adjust while viewing the 
wave pattern

Pattern selector

Display

Engine r/min

Idle speed

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

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

Short in the injector solenoid

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

AK303185AB

OSCILLOSCOPE

POWER PLANT ECU
CHECK HARNESS
CONNECTOR

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-1120

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

.

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.

AKX01605

WHEN IDLING

WHEN RACING

AB

AK203303

1

2 3

4

5 6

EGR VALVE
CONNECTOR

OSCILLOSCOPE

MB991658

AB

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