Mitsubishi Galant 9G. Manual — part 688

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-194

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• 3 minutes or more have passed since the engine

starting sequence was completed.

• Cylinder 1, 4 heated oxygen sensor (front) signal

voltage has continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Monitoring time: 7 seconds.

START

V

F

> =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK401409

V

F

< 0.2V

8secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-195

Judgment Criteria

• Input voltage supplied to the PCM interface circuit

is higher than 4.5 volts when 5 volts is applied to
the cylinder 1, 4 heated oxygen sensor (front)
output line via a resistor.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-6

.

.

TROUBLESHOOTING HINTS (The most
likely causes for this code to be set are:)

• Cylinder 1, 4 heated oxygen sensor (front) failed.

• Open or shorted circuit in cylinder1, 4 heated

oxygen sensor (front) output line, or harness
damage.

• Open circuit in cylinder 1, 4 heated oxygen sen-

sor (front) ground line, or harness damage.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

• MB991316: Test Harness

• MB991923: Power Plant ECU Check Harness

STEP 1. Using scan tool MB991958, check data list item 39:
Cylinder 1, 4 Heated Oxygen Sensor (front).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991958 to the data reading mode for item

39, Cylinder 1, 4 Heated Oxygen Sensor (front).

• Warming up the engine. When the engine is revved, the

output voltage should be 0.6 to 1.0 volt.

• Warming up the engine. When the engine is idling, the

output voltage should repeat 0.4 volt and 0.6 to 1.0 volt
alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

− How to

Cope with Intermittent Malfunctions

P.00-14

.

NO : Go to Step 2.

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

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STEP 2. Measure the sensor output voltage at cylinder 1, 4
heated oxygen sensor (front) connector B-37 by
backprobing
(1) Do not disconnect the connector B-37.
(2) Start the engine and run at idle.

(3) Measure the voltage between terminal No. 4 and ground by

backprobing.

• Warming up the engine. When the engine is 2,500 r/min,

the output voltage should repeat 0 to 0.8 volt alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?

YES : Go to Step 3.
NO : Go to Step 7.

AK303821

1

2

3

4

AB

CONNECTOR: B-37

CYLINDER 1, 4
HEATED OXYGEN
SENSOR (FRONT)

B-37 (GR)

HARNESS
CONNECTOR:
COMPONENT SIDE

1 2

4

3

AK201407

B-37 HARNESS
CONNECTOR:
HARNESS SIDE

AE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-197

STEP 3. Measure the sensor output voltage at PCM
connector B-22 by using power plant ECU check harness
special tool MB991923.
(1) Disconnect the all PCM connectors and connect power

plant ECU check harness special tool MB991923 between
the separated connectors.

(2) Start the engine and run at idle.

AK303016

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

CONNECTOR: B-22

B-22 (B)

PCM

AB

HARNESS CONNECTOR:
COMPONENT SIDE

AIR CLEANER

AK202956

104

96

94

95

93 92 91

99 98 97

103 102 101 100

108 107 106 105

113 112 111 110 109

AB

POWER PLANT ECU
CHECK HARNESS CONNECTOR

MB991923

PCM