Mitsubishi Montero (2002-2004). Manual - part 848

EMISSION CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-55

EMISSION CONTROL

GENERAL DESCRIPTION

M1173000100228

The emission control system consists of the fol-

lowing subsystems:

• Positive crankcase ventilation system

• Evaporative emission system

• Exhaust emission control system

DIAGNOSIS

M1173000700026

SPECIAL TOOLS

M1173000600029

SYMPTOM

PROBABLE CAUSE

REMEDY

Engine will not start or hard 
to start

Vacuum hose disconnected or damaged Repair or replace
The EGR valve is not closed.

Repair or replace

Malfunction of the evaporative emission 
purge solenoid

Repair or replace

Rough idle or engine stalls

The EGR valve is not closed.

Repair or replace

Vacuum hose disconnected or damaged. Repair or replace
Malfunction of the positive crankcase 
ventilation valve

Replace

Malfunction of the purge control system

Check the system; If there is a 
problem, check its component 
parts.

Engine hesitates or poor 
acceleration

Malfunction of the exhaust gas 
recirculation system

Check the system; If there is a 
problem, check its component 
parts.

Excessive oil consumption

Positive crankcase ventilation line 
clogged

Check positive crankcase 
ventilation system

Poor fuel mileage

Malfunction of the exhaust gas 
recirculation system

Check the system; If there is a 
problem, check its component 
parts.

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

MD998770 
Oxygen sensor wrench

MD998770-01 or General 
service tool

Removal/installation of 
heated oxygen sensor

MB995061
Purge flow indicator

MLR6890A

Inspection of purge 
control system

EMISSION CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-56

VACUUM HOSES

VACUUM HOSE ROUTING

M1173000900246

AK200798

EVAPORATIVE
EMISSION
CANISTER

EVAPORATIVE
EMISSION
VENTILATION
SOLENOID

FUEL
TANK

EVAPORATIVE
EMISSON PURGE
SOLENOID

THROTTLE BODY

VACUUM
ACTUATOR

VACUUM
TANK

INTAKE
MANIFOLD
TUNING
SOLENOID

FRONT

FUEL PRESSURE
REGULATOR

B: BLACK
*1: WHITE PAINT MARK

*1

B

B

B

B

B

B

B

AB

EMISSION CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-57

VACUUM CIRCUIT DIAGRAM

M1173007100166

VACUUM HOSE INSTALLATION

M1173007200011

1. When connecting the vacuum hoses, they should be 

securely inserted onto the nipples.

2. Connect the hoses correctly, using the VACUUM HOSE 

ROUTING as a guide.

AK200799

B

B

L

B

B: BLACK

THROTTLE BODY

INTAKE MANIFOLD

FROM AIR
CLEANER

FUEL
PRESSURE
REGULATOR

TO COMBUSTION
CHAMBER

EVAP 
PURGE
SOLENOID
(ON: OPEN)  

FUEL
TANK

EVAPORATIVE EMISSION
VENTILATION SOLENOID 
(ON: CLOSE)  

EVAPORATIVE
EMISSION 
CANISTER

AB

EMISSION CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-58

VACUUM HOSE CHECK

M1173007300018

1. Using the VACUUM HOSE ROUTING as a guide, check that 

the vacuum hoses are correctly connected.

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

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

POSITIVE CRANKCASE VENTILATION SYSTEM

GENERAL DESCRIPTION (POSITIVE CRANKCASE VENTILATION SYSTEM)

M1173005000174

The positive crankcase ventilation system is a sys-
tem for preventing the escape of blow-by gases from 
inside the crankcase into the atmosphere.
Fresh air is sent from the cleaner into the crankcase 
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 positive crankcase 
ventilation (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

COMPONENT LOCATION

M1173007400112

AK200800

BREATHER HOSE

VENTILATION HOSE

PCV VALVE

AB

AK200800

AK200801

POSITIVE CRANKCASE VENTILATION
(PCV) VALVE

AB