Mitsubishi Galant (2004+). Manual - part 900

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-417

STEP 6. Check the cylinder 1, 4 injector.

(1) Disconnect the cylinder 1, 4 injector connector B-01, B-27.

(2) Measure the resistance between each injector side 

connector terminal No. 1 and No. 2.

Standard value: 10.5 

− 13.5 ohms [at 20°C (68°F)]

Q: Is the measured resistance between 10.5 and 13.5 ohms 

[at 20

°C (68°F)]?

YES : Go to Step 7.
NO :  Replace the injector. Then go to Step 9.

STEP 7. Check the fuel pressure.

Refer to On-vehicle Service 

− Fuel Pressure Test 

P.13A-1104

.

Q: Is the fuel pressure normal?

YES : Repair it. Then go to Step 9.
NO :  Go to Step 8.

STEP 8. Replace the cylinder 1, 4 injector.

(1) Replace the cylinder 1, 4 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-5

.

(3) Check the diagnostic trouble code (DTC).
Q: Is DTC P0172 set?

YES : Replace the PCM. Then go to Step 9.
NO :  The inspection is complete.

STEP 9. 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-5

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0172 set?

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

M

1

2

AK303822

B-01 (GR)

B-27 (GR)

CONNECTORS: B-01, B-27

AB

HARNESS CONNECTOR:
COMPONENT SIDE

AK000559

2

1

INJECTOR SIDE
CONNECTOR

AB

M

1

2

AK303822

B-01 (GR)

B-27 (GR)

CONNECTORS: B-01, B-27

AB

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-418

DTC P0174: System too Lean (cylinder 2, 3)

CAUTION

If DTC P0174 has been set, TCL related DTC 
U1120 is also set. After P0174 has been diag-
nosed, don't forget to erase DTC U1120.

.

Fuel Trim Circuit

• Refer to DTC P0202 − Injector Circuit-cylinder 2 

P.13A-470

, DTC P0203 

− Injector Circuit-cylinder 

3 

P.13A-479

.

.

CIRCUIT OPERATION

• Refer to DTC P0202 − Injector Circuit-cylinder 2 

P.13A-470

, DTC P0203 

− Injector Circuit-cylinder 

3 

P.13A-479

.

.

TECHNICAL DESCRIPTION

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

trim value becomes too large.

• 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 lean.

.

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

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>

13A-419

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is lower than 100°C 

(212

°F) when the engine is started.

• Intake air temperature is lower than 60°C (140°F) 

when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C 

(171

°F).

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

Judgment Criteria

• Long-term fuel trim has continued to be higher 

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher 

than +10.0 percent for 5 seconds. <Federal>

or

• Short-term fuel trim has continued to be higher 

than +7.0 percent for 5 seconds. <California>

Check Conditions

• Engine coolant temperature is lower than 100°C 

(212

°F) when the engine is started.

• Intake air temperature is lower than 60°C (140°F) 

when the engine is started.

• Under the closed loop air/fuel ratio control.

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-420

• Engine coolant temperature is higher than 77°C 

(171

°F).

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

Judgment Criteria

• Long-term fuel trim has continued to be higher 

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher 

than +15.0 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than 100°C 

(212

°F) when the engine is started.

• Intake air temperature is higher than 60°C 

(140

°F) when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C 

(171

°F).

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

Judgment Criteria

• Long-term fuel trim has continued to be higher 

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher 

than +20.0 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than 100°C 

(212

°F) when the engine is started.

• Intake air temperature is higher than 60°C 

(140

°F) when the engine is started.

• Under the closed loop air/fuel ratio control.

• Engine coolant temperature is higher than 77°C 

(171

°F).

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

Judgment Criteria

• Long-term fuel trim has continued to be higher 

than +12.5 percent for 5 seconds.

or

• Short-term fuel trim has continued to be higher 

than +25.0 percent for 5 seconds.

Check Conditions

• Engine coolant temperature is higher than 77°C 

(171

°F).

• Under the closed loop air/fuel ratio control.

Judgment Criteria

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

percent for 5 seconds.

or

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

percent for 5 seconds.

.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 2 

− Fuel Trim Monitor 

P.13A-5

.

.

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.

• Air drawn in from gaps in gasket, seals, etc.

• Engine coolant temperature sensor failed.

• Intake air temperature sensor failed.

• Barometric pressure sensor failed.

• Manifold absolute pressure sensor failed.

• Exhaust leak.

• Use of incorrect or contaminated fuel.

• 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. Check for exhaust leak.
Q: Are there any abnormalities?

YES : Repair it. Then go to Step 15.
NO :  Go to Step 2.