Mitsubishi Galant 9G. Manual - part 1128

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-812

DTC P0456: Evaporative Emission System Leak Detected (Very Small Leak)

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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 

AC305053AC

EVAPORATIVE EMISSION
VENTILATION SOLENOID 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-813

TECHNICAL DESCRIPTION

• The PCM monitors the Evaporative Emission 

(EVAP) System pressure.

• The PCM controls the evaporative emission ven-

tilation solenoid. It closes the evaporative emis-
sion ventilation solenoid to seal the evaporative 
emission canister side of the system.

• The evaporative emission purge solenoid is 

opened to allow manifold vacuum to create low 
pressure (vacuum) in the EVAP system.

• When the EVAP system develops a vacuum of 2 

kPa (0.29 psi), the evaporative emission purge 
solenoid is closed and the fuel system vacuum is 
maintained at 2 kPa (0.29 psi).

• The PCM determines whether there is a leak in 

the EVAP system by monitoring the vacuum 
inside the fuel tank.

• The test is stopped when fuel vapor pressure 

exceeds predetermined limits.

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DESCRIPTIONS OF MONITOR METHODS

• Measure reverting pressure after depressurizing 

by intake manifold negative pressure and detect 
malfunction if reverting pressure rises largely.

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MONITOR EXECUTION

• Once per driving cycle.

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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

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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-814

LOGIC FLOW CHARTS (Monitor Sequence)

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DTC SET CONDITIONS

Check Conditions A: At Start up

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

when the engine is started.

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

less when the engine is started.

• The fuel level sensor output voltage is 2.4 − 3.7 

volts when the engine starts and the amount of 
remaining fuel is 40 

− 85 percent of capacity.

Check Conditions B: For Test to Run

• Barometric pressure is greater than 76 kPa (11 

psi).

• The fuel tank temperature is 33°C (91°F) or less.

• Fuel tank differential pressure sensor output volt-

age is 1 to 4 volts.

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-815

Check Conditions C: For Test to Stop

• Engine coolant temperature is greater than 20 °C 

(68 

°F).

• Intake air temperature is greater than -10 °C (14 

°F).

• When the evaporative emission purge solenoid 

and evaporative emission ventilation solenoid are 
closed, the pressure rises in the fuel tank is less 
than 324 Pa (0.047 psi).

• 10 seconds have elapsed from the start of the 

previous monitoring.

• Monitoring time: 10 − 14 minutes.

Judgment Criteria

• Internal pressure of the fuel tank has changed 

more than 1,177 

− 1,373 Pa (0.177 − 0.199 psi) in 

128 seconds after the tank and vapor line were 
closed.

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OBD-ll DRIVE CYCLE PATTERN

Refer to Diagnostic Function 

− OBD-ll Drive Cycle − 

Procedure 1 

− Evaporative Emission System Leak 

Monitor 

P.13B-6

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TROUBLESHOOTING HINTS (THE MOST 
LIKELY CAUSES FOR THIS CODE TO BE 
SET ARE:)

• Loose fuel cap.

• Fuel cap relief pressure is incorrect.

• Malfunction of the evaporative emission canister 

seal.

• Malfunction of the fuel tank, purge line or vapor 

line seal.

• Malfunction of the evaporative emission ventila-

tion solenoid.