Mitsubishi Galant (2004+). Manual - part 1265

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-753

STEP 16. Using scan tool MB991958, check data list item 
73: Fuel Tank Differential Pressure 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) Disconnect hose H from the evaporative emission canister, 

and plug the hose.

(3) Turn the ignition switch to the "ON" position.
(4) Remove the fuel cap.
(5) Set scan tool MB991958 to the data reading mode.

• Item 73, Fuel Tank Differential Pressure Sensor.

• The fuel tank pressure reading on the scan tool 

should be 

−1.5 to 1.5 kPa (−0.443 to 0.443 inHg).

(6) Connect the evaporative emission system pressure pump 

(Miller number 6872A) to the fuel tank filler tube by using 

fuel tank adapter (MLR-8382) and pressurize the fuel tank.

• The fuel tank pressure reading should increase.

(7) Turn the ignition switch to the "LOCK" (OFF) position. Then 

disconnect scan tool MB991958.

(8) Remove  the evaporative emission system pressure pump 

(Miller number 6872A) and the fuel tank adapter 
(MLR-8382), and reinstall the fuel cap.

(9) Connect hose H to the evaporative emission canister.
Q: Is the fuel tank pressure between 

−1.5 and 1.5 kPa 

(

−0.443 and 0.443 inHg)?

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 Malfunction 

P.00-6

). Go to 

Step 17.

NO :  Replace the PCM (Refer to 

P.13B-1146

). Then go to 

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC306778

AC

HOSE H

PLUG

AC306661

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-754

Step 17   .

STEP 17. Perform the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern (Refer to 

Diagnostic Function 

− OBD-ll Drive Cycle − Procedure 1 − 

Evaporative Emission System Leak Monitor 

P.13B-5

).

(2) Read the diagnostic trouble code (DTC).
Q: Is DTC P0453 set?

YES : Repeat the troubleshooting from Step 2.
NO :  The procedure is complete.

DTC P0455: Evaporative Emission System Leak Detected (Gross Leak)

AC306278

A

B

C

D

E

F

G

O

P

Q

N

M

L

H

I

J

K

AB

INTAKE MANIFOLD PLENUM

FUEL TANK

EVAPORATIVE EMISSION
VENTILATION SOLENOID

CHECK VALVE

EVAPORATIVE EMISSION
PURGE SOLENOID

EVAPORATIVE 
EMISSION CANISTER

ONBOARD REFUELING
VAPOR RECOVERY(ORVR)
VENT VALVE MODULE

SYSTEM DIAGRAM

CHAMBER

AC306400

AB

EVAPORATIVE EMISSION CANISTER

AC306388AB

EVAPORATIVE EMISSION
PURGE SOLENOID 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-755

.

TECHNICAL DESCRIPTION

• The fuel tank may be under a slight pressure or 

vacuum depending on the state of the Evapora-
tive Emission (EVAP) System. The PCM monitors 
and responds to these pressure/vacuum 
changes. If the pressure/vacuum varies from the 
specified range, the PCM will set DTC P0455.

• The PCM energizes the evaporative emission 

ventilation solenoid to shut off the evaporative 
emission canister outlet port.

• The evaporative emission purge solenoid is acti-

vated to apply engine manifold vacuum to the 
EVAP system.

• When the fuel system develops a vacuum of 2 

kPa (0.29 psi), the evaporative emission purge 
solenoid is turned "off" and the fuel system vac-
uum is maintained at 2 kPa (0.29 psi).

• The PCM determines whether there is a leak or 

clog in the fuel system by measuring the change 
in vacuum inside the fuel tank.

• The test is stopped when fuel vapor pressure is 

determined to be too high.

.

DESCRIPTIONS OF MONITOR METHODS

• Depressurizing EVAP system by intake manifold 

negative pressure is impossible within specified 
period.

.

MONITOR EXECUTION

• Once per driving cycle.

.

MONITOR EXECUTION CONDITIONS (Other 
Monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Evaporative emission purge solenoid monitor

• Evaporative emission purge system monitor

• Fuel tank differential pressure sensor monitor

• Evaporative emission ventilation solenoid monitor

• Fuel level sensor monitor

• Fuel temperature sensor monitor

 Sensor (The sensors below are determined to be 

normal)

• Mass airflow sensor

• Barometric pressure sensor

• Intake air temperature sensor

• Engine coolant temperature sensor

.

AC305053AC

EVAPORATIVE EMISSION
VENTILATION SOLENOID 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-756

LOGIC FLOW CHARTS (Monitor Sequence)

.

DTC SET CONDITIONS

Check Conditions A: At Start up

• Intake air temperature is 36°C (97°F) or less 

upon engine start up.

• The engine coolant temperature is 36°C (97°F) or 

less upon engine start up.

Check Conditions B: For Test to Run

• The engine coolant temperature is 60°C (140°F) 

or greater and the fuel tank is 15 

− 40 percent full.

• The engine coolant temperature is 20°C (68°F) or 

greater and the fuel tank is 40 

− 85 percent full.

• The engine speed is greater than or equal to 

1,600 r/min.

• Barometric pressure is greater than 76 kPa (11 

psi).

AC306649

0.04in, 0.02in GROSS LEAK MONITOR

START

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

MONITORING
CONDITIONS?

DEPRESSURIZE FUEL TANK PRESSURE

GROSS LEAK

MONITORING CONDITIONS

SHUT PURGE LINE

MEASURE REVERTING
PRESSURE :    PFT

PFT > PT

SPECIFIED TIMES

MONITORED

MALFUNCTION

END

SPECIFIED TIMES

HAVE PASSED

MALFUNCTION

(GROSS LEAK)

GOOD