Mitsubishi Galant 9G. Manual - part 937

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-48

DTC SET CONDITIONS <Range/Performance problem - low input>
Logic Flow Chart

.

Check Conditions

• Throttle position sensor output voltage is 1.5 volt 

or higher.

Judgement Criteria

• Mass airflow sensor output voltage has continued 

to be 1.8 volts or lower for 2 seconds.

.

START

END

NO

YES

YES

YES

NO

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 2secs

OUTPUT VOLTAGE

< =1.8V

MONITORING

CONDITIONS

AK401683

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-49

DTC SET CONDITIONS <Range/Performance problem - high input>
Logic Flow Chart

.

Check Conditions

• Throttle position sensor output voltage is 1.0 volt 

or lower.

Judgement Criteria

• Mass airflow sensor output voltage has continued 

to be 3.5 volts or higher for 2 seconds.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13B-6

.

.

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

• Mass airflow sensor failed.

• Mass airflow sensor circuit harness damage, or 

connector damage.

• PCM failed. 

START

END

NO

NO

YES

YES

YES

NO

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 2secs

OUTPUT VOLTAGE

> =3.50V

MONITORING

CONDITIONS

AK302375

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-50

DIAGNOSIS

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

STEP 1. Using scan tool MB991958, check data list item 12: 
Mass Airflow Sensor.

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 

12, Mass Airflow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°C 

to 95

°C (176°F to 203°F).

• The standard value during idling should be between 2.0 

and 6.0 g/sec.

• When the engine is revved, the mass airflow rate should 

increase according to the increase in engine speed.

(5) 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.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-51

STEP 2. Check harness connector B-10 at mass airflow 
sensor and harness connector B-17X at MFI relay for 
damage.

Q: Is the harness connector in good condition?

YES : Go to Step 3.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 9.

AK303015

2

1

3

4

AB

B-10 (GR)

CONNECTOR: B-10

HARNESS
CONNECTOR:
COMPONENT SIDE

1

2

3

4

AK303017

CONNECTOR: B-17X

FRONT OF VEHICLE

B-17X

AB

HARNESS
CONNECTOR:
COMPONENT SIDE

RELAY BOX