Mitsubishi Montero Sport (2004+). Manual — part 128

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-107

EVAPORATIVE EMISSION CONTROL SYSTEM

GENERAL DESCRIPTION (EVAPORATIVE EMISSION SYSTEM)

M1173005100416

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 ple-
num 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 the 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, and used to
monitor for OBD-II EVAP leaks. This solenoid is nor-
mally 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 differ-
ential pressure sensor monitors the fuel vapor pres-
sure to detect OBD-II EVAP leaks. The fuel overflow
limiter valve and the leveling valve prevent fuel from
being overfilled. The fuel cut off 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.

SYSTEM DIAGRAM

AK300573

FUEL TANK DIFFERENTIAL
PRESSURE SENSOR

LIQUID SEPARATOR

EVAPORATIVE
EMISSION
CANISTER

EVAPORATIVE
EMISSION
PURGE
SOLENOID
ON: OPEN

PCM

INTAKE AIR TEMPERATURE
SENSOR

ENGINE COOLANT
TEMPERATURE SENSOR

VOLUME AIRFLOW SENSOR

FUEL
TANK

MFI RELAY

FUEL OVERFLOW
LIMITER VALVE

FUEL CUT
OFF VALVE

LEVELING VALVE

EVAPORATIVE EMISSION
VENTILATION VALVE

AIR FILTER

EVAPORATIVE EMISSION
VENTILATION SOLENOID
ON: CLOSED

AC

BAROMETRIC PRESSURE
SENSOR

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-108

COMPONENT LOCATION

M1173007500227

PURGE CONTROL SYSTEM CHECK (PURGE FLOW CHECK)

M1173001400307

AK303327AB

EVAPORATIVE EMISSION PURGE SOLENOID

AK301842 AB

SPARE TIRE

EVPORATIVE EMISSION VENTILATION
SOLENOID

AK300654

THROTTLE BODY

INTAKE MANIFOLD

FROM
AIR CLEANER

TO
COMBUSTION
CHAMBER

OFF

ON

EVAPORATIVE EMISSION
PURGE SOLENOID
(ON: OPENED)

PURGE
FLOW
INDICATOR
(MB995061)

PURGE HOSE

EVAPORATIVE EMISSION
CANISTER

AB

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-109

Required Special Tool:
MB995061: Purge Flow Indicator
1. Disconnect the purge hose from the evaporative emission

(EVAP) purge solenoid, and connect special tool MB995061
between the EVAP purge solenoid and the purge hose.

2. Before checks, set the vehicle in the following conditions:

• Engine coolant temperature: 80 − 95°C (176 − 203°F)

• Lights, electric cooling fan and accessories: OFF

• Transaxle: P range

NOTE: Vehicles for Canada, the headlight, taillight, etc.
remain lit even when the lighting switch is in "OFF" position
but this is no problem for checks.

3. Run the engine at idle for more than four minutes.
4. Check the purge flow volume when engine is revved

suddenly several times.

Standard value: Momentarily 20 cm

3

/s (2.5 SCFH) or

more.

5. If the purge flow volume is less than the standard value,

check it again with the vacuum hose disconnected from the
EVAP canister. If the purge flow volume is less than the
standard value, check the vacuum port and the vacuum
hose for clogging. Also check the EVAP purge solenoid. If
the purge flow volume is at the standard value, replace the
EVAP canister.

EVAPORATIVE EMISSION PURGE SOLENOID
CHECK

M1173001700267

1. Disconnect the vacuum hose (black, black with red paint

mark) from the evaporative emission (EVAP) purge solenoid
valve.
NOTE: When disconnecting the vacuum hose, always place
an identification mark so that it can be reconnected at its
original position.

2. Disconnect the harness connector.
3. Connect a hand vacuum pump to nipple (B) of the EVAP

purge solenoid valve (refer to the illustration at left).

4. As described in the chart below, check airtightness by

applying a vacuum with voltage applied directly from the
battery to the EVAP purge solenoid valve and without
applying voltage.

BATTERY POSITIVE
VOLTAGE

NORMAL CONDITION

Applied

Vacuum leaks

Not applied

Vacuum maintained

AKX00341

A

B

AKX00341AC

EMISSION CONTROL

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ENGINE AND EMISSION CONTROL

17-110

5. Measure the resistance between the terminals of the EVAP

purge solenoid valve.

Standard value: 30

− 34 Ω [at 20°C (68°F)]

6. Replace the solenoid if resistance is out of specification.

VOLUME AIRFLOW SENSOR CHECK

M1173007900559

To inspect the sensor, refer to GROUP 13A, Multiport Fuel
Injection (MFI)

− Multiport Fuel Injection (MFI) Diagnosis −

Diagnostic Trouble Code Chart

P.13A-26

.

BAROMETRIC PRESSURE SENSOR CHECK

M1173008000311

To inspect the sensor, refer to GROUP 13A, Multiport Fuel
Injection (MFI)

− Multiport Fuel Injection (MFI) Diagnosis −

Diagnostic Trouble Code Chart

P.13A-26

.

ENGINE COOLANT TEMPERATURE SENSOR
CHECK

M1173008100620

To inspect the sensor, refer to GROUP 13A, Multiport Fuel
Injection (MFI)

− Multiport Fuel Injection (MFI) Diagnosis −

Diagnostic Trouble Code Chart

P.13A-26

.

INTAKE AIR TEMPERATURE SENSOR CHECK

M1173008200315

To inspect the sensor, refer to GROUP 13A, Multiport Fuel
Injection (MFI)

− Multiport Fuel Injection (MFI) Diagnosis −

Diagnostic Trouble Code Chart

P.13A-26

.

FUEL TANK DIFFERENTIAL PRESSURE SENSOR
CHECK

M1173007700254

To inspect the sensor, refer to GROUP 13B, Fuel Supply

− Fuel

Tank

− Fuel Tank Inspection − Fuel Tank Differential Pressure

Sensor Check

P.13B-7

.

EVAPORATIVE EMISSION VENTILATION
SOLENOID CHECK

M1173007800198

Refer to Emission Control

− Evaporative Emission Canister and

Fuel Tank Pressure Relief Valve

− Inspection − Evaporative

Emission Ventilation Solenoid Check .

AKX00342