Mitsubishi Galant (2004+). Manual - part 198

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-83

VACUUM HOSE CHECK

M1173007300171

1. Using the VACUUM HOSE ROUTING diagram as a guide, 

check that the vacuum hoses are correctly connected.

2. Check the connection of the vacuum hoses, (removed, 

loose, etc.) and confirm that there are no sharp bends or 
damage.

POSITIVE CRANKCASE VENTILATION SYSTEM

GENERAL DESCRIPTION (POSITIVE CRANKCASE VENTILATION SYSTEM)

M1173005000293

The positive crankcase ventilation (PCV) system pre-
vents the escape of blow-by gases from inside the 
crankcase into the atmosphere.
Fresh air is sent from the air cleaner into the crank-
case through the breather hose to be mixed with the 
blow-by gas inside the crankcase.
The blow-by gas inside the crankcase is drawn into 
the intake manifold through the PCV valve.

The PCV valve is designed to lift the plunger accord-
ing to the intake manifold vacuum so as to regulate 
the flow of blow-by gas properly.
In other words, the blow-by gas flow is regulated dur-
ing low load engine operation to maintain engine sta-
bility, while the flow is increased during high load 
operation to improve the ventilation performance.

SYSTEM DIAGRAM
<2.4L ENGINE>

AK300553

VENTILATION HOSE

POSITIVE CRANKCASE
VENTILATION VALVE

BREATHER HOSE

AB

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-84

<3.8L ENGINE>

COMPONENT LOCATION

M1173007400189

POSITIVE CRANKCASE VENTILATION SYSTEM 
CHECK

M1173001100232

1. Remove the positive crankcase ventilation (PCV) valve from 

the rocker cover, then reconnect the PCV valve to the 
vacuum supply hose.

2. With the engine idling, put your finger on the open end of the 

PCV valve, and check for negative pressure (vacuum).
NOTE: At this time, the plunger in the PCV valve should 
move back and forth as the open end is covered and uncov-
ered.

3. If negative pressure is not felt, clean or replace the PCV 

valve. Inspect the vacuum supply hose and vacuum supply 
hose port for restriction or plugged condition.

AK303639

POSITIVE CRANKCASE 
VENTILATION VALVE

VENTILATION HOSE

BREATHER HOSE

AB

AK301395AB

POSITIVE CRANKCASE VENTILATION VALVE
<2.4L ENGINE>

AK203691AC

POSITIVE CRANKCASE VENTILATION VALVE
<3.8L ENGINE>

AK203692

POSITIVE CRANKCASE
VENTILATION VALVE

AC

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-85

POSITIVE CRANKCASE VENTILATION VALVE 
CHECK

M1173001200228

1. Hold the positive crankcase ventilation (PCV) valve with the 

vacuum side down. Insert a thin rod, and using light 
pressure, depress the end of the PCV valve spring by 5 

− 10 

mm (0.2 

− 0.3 inch). Release pressure on the rod to see if 

the PCV valve spring will lift the rod to its original position. 

2. If the rod returns quickly to its original position, the PCV 

valve is OK. If the stick does not return quickly, clean or 
replace the PCV valve.

EVAPORATIVE EMISSION CONTROL SYSTEM

GENERAL DESCRIPTION (EVAPORATIVE EMISSION SYSTEM)

M1173005100386

The evaporative emission (EVAP) system prevents 
fuel vapors generated in the fuel tank from escaping 
into the atmosphere.
Fuel vapors from the fuel tank flow through the vapor 
pipe/hose to be stored temporarily in the EVAP can-
ister. 
When the vehicle is in operation, fuel vapors stored 
in the EVAP canister flow through the EVAP purge 
solenoid, purge port and intake manifold plenum to 
the combustion chamber.
When the engine coolant temperature is low or when 
the intake air quantity is small (when the engine is at 
idle, for example), the powertrain control module 
(PCM) brings the EVAP purge solenoid into the OFF 
state to shut off the fuel vapor flow to the intake man-
ifold plenum. This ensures driveability when the 
engine is cold or running under low load and also 
stabilizes the emission level.

An EVAP ventilation solenoid is provided between 
the EVAP canister and atmosphere to monitor for 
OBD-II EVAP leaks. This solenoid is normally OFF. 
However, it turns ON when monitoring the OBD-II 
EVAP leaks and shuts off the atmosphere flow to the 
EVAP canister. Then the fuel tank differential pres-
sure sensor monitors the fuel vapor pressure to 
detect OBD-II EVAP leaks. The fuel overflow limiter 
valve and the leveling valve prevent fuel from being 
overfilled. The fuel overflow limiter valve and the lev-
eling valve prevents fuel leaks if the vehicle is rolled 
over in an accident.
The EVAP ventilation valve releases the air from the 
fuel tank through the EVAP canister into the atmo-
sphere when the fuel tank pressure increases due to 
refueling, etc. The EVAP ventilation valve and the air 
filter supply the atmospheric air to the EVAP canister 
when the fuel tank pressure decreases. 

AK301831

5 – 10 mm

(0.2 – 0.3 in)

THIN ROD
(VERY SMOOTH)

POSITIVE 
CRANKCASE 
VENTILATION 
VALVE

VACUUM SIDE

AB

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-86

SYSTEM DIAGRAM
<2.4L ENGINE>

AK300555

FUEL TANK DIFFERENTIAL
PRESSURE SENSOR

LIQUID SEPARATOR

EVAPORATIVE 
EMISSION 
CANISTER

EVAPORATIVE 
EMISSION 
PURGE 
SOLENOID 
ON: OPEN

PCM

BAROMETRIC PRESSURE 
SENSOR

INTAKE AIR TEMPERATURE
SENSOR

ENGINE COOLANT 
TEMPERATURE SENSOR

MASS AIRFLOW SENSOR

FUEL
TANK

MFI RELAY

FUEL OVERFLOW
LIMITER VALVE

FUEL CUT
OFF VALVE

LEVELING VALVE

EVAPORATIVE EMISION 
VENTILATION VALVE

AIR FILTER

EVAPORATIVE EMISSION 
VENTILATION SOLENOID
ON: CLOSED

AB