Mitsubishi Lancer Evolution 7. Manual — part 237
ENGINE AND EMISSION CONTROL -
Emission Control System
PCV valve
17-9
COMPONENT LOCATION
POSITIVE CRANKCASE VENTILATION SYSTEM
CHECK
1. Remove the ventilation hose from the PCV valve.
2. Remove the PCV valve from the rocker cover.
3. Reinstall the PCV valve at the ventilation hose.
4. Start the engine and run at idle.
5. Place a finger at the opening of the PCV valve and check
that vacuum of the intake manifold is felt.
NOTE
At this moment, the plunger in the PCV valve moves
back and forth.
6. If vacuum is not felt, clean the PCV valve or replace
it.
PCV VALVE CHECK
1. Insert a thin rod into the PCV valve from the side shown
in the illustration (rocker cover installation side), and move
the rod back and forth to check that the plunger moves.
2. If the plunger does not move, there is a clogging in the
PCV valve. In this case, clean or replace the PCV valve.
PCV valve
PCV valve
ENGINE AND EMISSION CONTROL -
Emission Control System
Vacuum tank
Alternator
Purge control solenoid valve
17-10
EVAPORATIVE EMISSION CONTROL SYSTEM
GENERAL INFORMATION
The evaporative emission control system prevents
fuel vapours generated in the fuel tank from
escaping into the atmosphere.
Fuel vapours from the fuel tank flow through the
fuel tank pressure control valve and vapour
pipe/hose to be stored temporarily in the canister.
When driving the vehicle, fuel vapours stored in
the canister flow through the purge solenoid and
purge port and go into the intake manifold to be
sent 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 engine control
unit turns the purge solenoid off to shut off the
fuel vapour flow to the intake manifold.
This does not only insure the driveability when the
engine is cold or running under low load but also
stabilize the emission level.
SYSTEM DIAGRAM
Battery
Intake air
temperature sensor
Barometric pressure
sensor
Check
valve
Canister
Control
relay
Purge control
solenoid valve
(ON: Open)
Engine-ECU
Engine coolant
temperature sensor
Air flow sensor
COMPONENT LOCATION
ENGINE AND EMISSION CONTROL -
Emission Control System
17-11
PURGE CONTROL SYSTEM CHECK
1. Disconnect the vacuum hose (red stripe) from throttle
body and connect it to a hand vacuum pump.
2. Plug the nipple from which the vacuum hose was removed.
3. When the engine is cold or hot, apply a vacuum of 53
kPa, and check the condition of the vacuum.
When engine is cold
(Engine coolant temperature: 40_C or less)
Engine condition
Normal condition
At idle
Vacuum is maintained
3,000 r/min
When engine is hot
(Engine coolant temperature: 80_C or higher)
Engine condition
Normal condition
At idle
Vacuum is maintained
3,000 r/min (within 3
minutes after engine starts)
Vacuum will leak.
PURGE PORT VACUUM CHECK
1. Disconnect the vacuum hose (red stripe) from the throttle
body purge vacuum nipple and connect a hand vacuum
pump to the nipple.
2. Confirm that the vacuum is approximately constant
regardless of the engine rotation speed.
NOTE
If vacuum changes, it is possible that the throttle body
purge port maybe clogged and require cleaning.
Red stripe
Plug
Throttle body
Red stripe
Throttle body
Vac-
uum
Engine speed (r/min)
ENGINE AND EMISSION CONTROL -
Emission Control System
17-12
PURGE CONTROL SOLENOID VALVE CHECK
NOTE
When disconnecting the vacuum hose, always make a mark
so that it can be reconnected at original position.
1. Disconnect the vacuum hose from the solenoid valve.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to nipple (A) of the solenoid
valve (refer to the illustration at left).
4. Check airtightness by applying a vacuum with voltage
applied directly from the battery to the purge control
solenoid valve and without applying voltage.
Battery voltage
Normal condition
Applied
Vacuum leaks
Not applied
Vacuum maintained
5. Measure the resistance between the terminals of the
solenoid valve.
Standard value: 30 - 34 Ω (at 20_C)
CHECK VALVE CHECK
Connect a hand vacuum pump to the check valve, apply
vacuum and check the airtightness.
Connected nipple colour
Normal condition
Black
Vacuum leaks
Brown
Vacuum is maintained
Battery
A
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