Mitsubishi Galant 9G. Manual - part 747

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-430

STEP 14. Replace the cylinder 2, 3 injector.
(1) Replace the cylinder 2, 3 injector.
(2) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Procedure 2 − 

Fuel Trim Monitor 

P.13A-6

.

(3) Check in the diagnostic trouble code (DTC).
Q: Is DTC P0174 set?

YES : Replace the PCM. Then go to Step 15.
NO :  The inspection is complete.

STEP 15. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Procedure 2 − 

Fuel Trim Monitor 

P.13A-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0174 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

DTC P0175: System too Rich (cylinder 2, 3)

CAUTION

If DTC P0175 has been set, TCL related DTC 
U1120 is also set. After P0175 has been diag-
nosed, don't forget to erase DTC U1120.

.

Fuel Trim Circuit

• Refer to DTC P0202 − Injector Circuit-cylinder 2 

P.13A-474

, DTC P0203 

− Injector Circuit-cylinder 

3 

P.13A-484

.

.

CIRCUIT OPERATION

• Refer to DTC P0202 − Injector Circuit-cylinder 2 

P.13A-474

, DTC P0203 

− Injector Circuit-cylinder 

3 

P.13A-484

.

.

TECHNICAL DESCRIPTION

• If a malfunction occurs in the fuel system, the fuel 

trim value becomes too small.

• The PCM checks whether the fuel trim value is 

within a specified range.

.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 2, 3 air/fuel learning value (long time fuel 

trim) and air/fuel feedback integral value (short 
time fuel trim) are too rich.

.

MONITOR EXECUTION

Continuous

.

MONITOR EXECUTION CONDITIONS 
(Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Misfire monitor

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor

• Engine coolant temperature sensor 

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.

M

1

2

AK303831

B-30 (GR) B-03 (GR)

CONNECTORS: B-03, B-30

AB

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-431

DTC SET CONDITIONS
Logic Flow Chart

.

DTC SET CONDITIONS

Check Conditions

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 76°C 

(169

°F).

• Mass airflow sensor output is 6 g/sec or more.

Judgment Criteria

• Long-term fuel trim has continued to be lower 

than 

−12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be lower 

than 

−10.0 percent for 5 seconds.

Check Conditions

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 76°C 

(169

°F).

• Mass airflow sensor output is 6 g/sec or less.

Judgment Criteria

• Long-term fuel trim has continued to be lower 

than 

−12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be lower 

than 

−15.0 percent for 5 seconds.

K

LRN

: LONG-TERM TRIM

K

I

: SHORT-TERM TRIM

K0 : MAXIMUM LIMIT OF LONG-TERM TRIM
K1 : MAXIMUM LIMIT OF SHORT-TERM TRIM
K2 : MINIMUM LIMIT OF LONG-TERM TRIM
K3 : MINIMUM LIMIT OF SHORT-TERM TRIM

START

MONITORING

CONDITIONS

END

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

K

LRN

 > K0

MALFUNCTION

GOOD

K

LRN

 < K2

K

I

< K3

K

I

> K1

CONTINUOUS FAILURE

FOR 5secs

AK204050

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-432

Check Conditions

• Engine coolant temperature is higher than 76°C 

(169

°F).

• Under the closed loop air/fuel ratio control.

Judgment Criteria

• Long-term fuel trim has continued to be −12.5 

percent for 2 seconds.

or

• Short-term fuel trim has continued to be −25.0 

percent for 2 seconds.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 2 

− Fuel Trim Monitor 

P.13A-6

.

.

TROUBLESHOOTING HINTS (The most likely 

causes for this code to be set are:)

• Mass airflow sensor failed.

• Injector (Number 2, 3) failed.

• Incorrect fuel pressure.

• Engine coolant temperature sensor failed.

• Intake air temperature sensor failed.

• Barometric pressure sensor failed.

• Manifold absolute pressure sensor failed.

• Harness damage in cylinder 2, 3 injector circuit or 

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

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).

• When idling, between 2.0 and 6.0 g/sec.

• When 2,500 r/min, between 6.5 and 14.5 g/sec.

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

YES : Go to Step 2.
NO :  Refer to DTC P0101 

− Mass Airflow Circuit 

Range/Performance Problem 

P.13A-46

, DTC P0102 

− Mass Airflow Circuit Low Input 

P.13A-55

, DTC 

P0103 

− Mass Airflow Circuit High Input 

P.13A-65

.

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-433

STEP 2. Using scan tool MB991958, check data list item 13: 
Intake Air Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 

13, Intake Air Temperature Sensor.

• The intake air temperature and temperature shown with 

the scan tool should approximately match.

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

YES : Go to Step 3.
NO :  Refer to DTC P0111 

− Intake Air Temperature Circuit 

Range/Performance Problem 

P.13A-107

 DTC P0112 

− Intake Air Temperature Circuit Low Input 

P.13A-116

, DTC P0113 

− Intake Air Temperature 

Circuit High Input 

P.13A-123

.

STEP 3. Using scan tool MB991958, check data list item 21: 
Engine Coolant Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 

21, Engine Coolant Temperature Sensor.

• The engine coolant temperature and temperature 

shown with the scan tool should approximately match.

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

YES : Go to Step 4.
NO :  Refer to DTC P0116 

− Engine Coolant Temperature 

Circuit Range/Performance Problem 

P.13A-133

, DTC 

P0117 

− Engine Coolant Temperature Circuit Low 

Input 

P.13A-142

, DTC P0118 

− Engine Coolant 

Temperature Circuit High Input 

P.13A-149

.

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827

AK303804AB

MB991910

DATA LINK
CONNECTOR

MB991824

MB991827