
EMISSION CONTROL
ENGINE AND EMISSION CONTROL17-10
CRANKCASE VENTILATION SYSTEMM2171000400129
A blow-by gas reduction device prevents blow-by 
gas from being expelled into the atmosphere and is 
of closed type. A positive crankcase ventilation 
(PCV) valve is provided in the ventilation hose from 
the rocker cover to the intake manifold. During low 
load driving, clean air is supplied to the crankcase by 
the air intake hose via the breather hose and rocker 
cover, and it mixes with the blow-by gas in the crank
-
case. The blow-by gas in the crankcase is induced to 
the intake manifold through the rocker cover and 
PCV valve. During high load driving, blow-by gas in 
the crankcase is induced to the intake manifold 
through the rocker cover and PCV valve and at the 
same time also via the air intake hose and throttle 
body due to negative pressure in the air cleaner.
Emission 
reduction 
systemsAir-fuel ratio 
feedback 
controlDecrease of CO, HC and NOx
Controls air-fuel ratio of air-fuel mixture to 
become theoretical air-fuel ratio (about 14.7), 
which is when the 3-way catalytic converter's 
cleaning performance is best. It also controls 
optimum fuel supply based on coolant 
temperature, driving conditions etc.
•ECM
•Mass airflow sensor
•Injectors
•Heated oxygen sensor
•Crankshaft position sensor 
etc.
Catalytic 
converterDecrease of CO, HC and NOx
It facilitates oxidation of CO and HC and 
reduction of NOx so that all 3 component gases 
are cleaned simultaneously.
Monolith catalyst
HC trap 
catalytic 
converter 
During cold operation of engine, exhaust HC is 
temporarily absorbed. And then Exhaust HC is 
released when temperature reaches to level at 
which catalyst is activated. This allows HC to be 
reduced.
Monolith catalyst
System Objective / Function Composition parts
AK604142
Air cleaner
PCV valve
AB
Ventilation hose
Breather hose
Flow of blow-by gas and clean air (low load area)
Flow of blow-by gas (high load area) 

EMISSION CONTROL
ENGINE AND EMISSION CONTROL17-11
POSITIVE CRANKCASE VENTILATION (PCV) 
VA LV E
PCV valve lifts the plunger according to negative pressure in 
the intake manifold to create appropriate ventilation for the 
crankcase.
EVAPORATIVE EMISSION CONTROL SYSTEMM2171000200147
HC (hydrocarbon) generated in the fuel tank are 
adsorbed by the active carbon in the canister and 
stored. HC stored in the canister is introduced to the 
intake manifold when engine is in operation where it 
is mixed with intake air and combusted. ECM intro
-
duces optimum HC amount according to driving con-
ditions and so performs duty control on the 
evaporative emission purge solenoid. Also, the evap
-
orative emission purge solenoid is closed during 
deceleration or immediately after engine start to 
restrict change in air-fuel ratio and prevent engine 
from stalling.
AK602324AC
Plunger
From
rocker
coverTo intake
manifold
Spring
AK604143
Evaporative emission 
purge solenoid
Mass airflow sensor
ECM Intake air temperature sensor
Manifold absolute pressure
sensor
Engine coolant temperature
sensor
Throttle position sensor
Crankshaft position sensorEvaporative emission 
canister
AB
MFI relay
Battery 

EMISSION CONTROL
ENGINE AND EMISSION CONTROL17-12
EVAPORATIVE EMISSION PURGE SOLENOID
An evaporative emission purge solenoid is installed in the 
intake manifold.The evaporative emission purge solenoid con
-
trols the intake volume of fuel vapor gas from the canister. The 
evaporative emission purge solenoid is a duty control type 
solenoid valve. When current is not passing through the coil, 
nipple A is kept airtight and fuel vapor gas cannot be sucked in. 
When current passes through the coil, air can pass between 
nipple A and B and fuel vapor gas is sucked in. ECM changes 
the ON duty ratio according to engine's operating condition to 
control the intake volume of fuel vapor gas.
EXHAUST GAS RECIRCULATION (EGR) SYSTEM 
When the combustion gas temperature becomes 
high, generation of the environment polluting NOx 
(nitrogen oxides) increases rapidly. EGR system is 
used to decrease the volume of NOx generated. 
EGR system re-circulates exhaust gas inside the 
intake manifold. It increases specific heat of the com
-
bustion gases and reduces combustion speed to lower the combustion temperature and reduce the 
volume of NOx generated. ECM calculates the EGR 
introduction volume according to engine operating 
conditions and controls the EGR valve opening angle 
at optimum. Also, immediately after the ignition 
switch ON signal is input, it drives fully closed step
-
per motor and performs initialization.
AK604745AC
B To canister
To intake manifoldA
AK602245AD
12V
ONOFF
0V100 ms
Evaporative
emission
purge solenoidFrom MFI relay
ECM
AK502987AE
ECMMass airflow sensor
Intake air temperature sensor
Manifold absolute
pressure sensor
Engine coolant
temperature sensor
Throttle position sensor
Crankshaft position sensor BatteryEGR valve
(stepper motor) 

15-1
GROUP 15
INTAKE AND 
EXHAUST
CONTENTS
AIR DUCT AND AIR CLEANER  . . . .15-2
INTAKE MANIFOLD  . . . . . . . . . . . . .15-3
EXHAUST MANIFOLD . . . . . . . . . . . .15-4
EXHAUST PIPE AND MUFFLER . . . .15-4 

INTAKE MANIFOLD
INTAKE AND EXHAUST15-3
INTAKE MANIFOLDM2150005000239
The intake manifold is made of plastic for weight 
reduction, and the surface roughness of the inner 
walls of the ports has been improved to reduce 
intake resistance.
AK502555
Intake manifold
AD
Air intake plenum
tank resonator 

EXHAUST MANIFOLD
INTAKE AND EXHAUST15-4
EXHAUST MANIFOLDM2150006000566
A clamshell type exhaust manifold is used.
A SUS pipe type exhaust manifold is used.
EXHAUST PIPE AND MUFFLERM2150003000783
The exhaust system is composed of the front 
exhaust pipe, center exhaust pipe, and main muffler, 
and it has the following characteristics.•Fewer, more environmentally-friendly rubber 
hangers to reduce vibration from exhaust system.
•Straighter exhaust pipe to reduce noise.
CONSTRUCTION DIAGRAM
AK603623
AB
AC608352Front exhaust pipeCenter exhaust pipeMain mufflerAB
Heated oxygen sensor (front)
Heated oxygen sensor (rear) 
AC608488Front exhaust pipeCenter exhaust pipeMain mufflerAB
Heated oxygen 
sensor (rear)
Heated oxygen sensor (3rd) 
sensor (front) 

GENERAL DESCRIPTION
MULTIPORT FUEL SYSTEM (MFI)13A-3
System Block Diagram
AK604116
Mass airflow sensor
Intake air temperature sensor
Intake camshaft position
sensor
Exhaust camshaft position
sensor
Crankshaft position sensor Throttle position sensor (main)
Throttle position sensor (sub)
Accelerator pedal position
sensor (sub) Accelerator pedal position
sensor (main) Engine coolant temperature
sensor Manifold absolute pressure
sensor
Heated oxygen sensor (front)
Heated oxygen sensor (rear)
Power steering pressure
switch Engine oil pressure switch Generator L terminal
Ignition switch-ST
Power supply Ignition switch-IG
CAN communication
(input signal)
· A/C switch
· Vehicle speed 
· Fuel level sensor
· Transmission range switch
  
sensor Heated oxygen sensor
(3rd)*
Knock sensor
Generator FR terminal
Fuel tank temperature sensor
Vehicle speed sensor 
[1] Fuel injection control
[2] Ignition timing control
[3] Throttle valve opening angle
     control and idle speed control
[4] 
MIVEC (Mitsubishi Innovative
     Valve timing Electronic Control
     system)
[5] Power supply control
     (Power supply to sensor,
      actuator)
[6] Fuel pump relay control
[7] Starter relay control
[8] Heated oxygen sensor heater
     control
[9] A/C compressor relay control
[10] Generator control
[11] Evaporative emission purge
       control
[12] EGR control
[13] Diagnosis output
[14] RAM data transmission
CAN communication
(output signal) Intake engine oil control
valve
A/C compressor relay No. 2 injector
No. 3 injector
No. 4 injector
Heated oxygen sensor (front)
heater
Heated oxygen sensor (rear)
heater Throttle actuator control
motor
Throttle actuator control
motor relay No. 1 injector
No. 1 ignition coil
No. 2 ignition coi
No. 3 ignition coi
No. 4 ignition coi
Fuel pump relay
Generator G terminal Heated oxygen sensor (3rd)
heater*
Multiport fuel injection (MFI)
relay Exhaust engine oil control
valve
Evaporative emission ventilation
solenoid Evaporative emission purge
solenoid
EGR valve (stepper motor)*
Starter relay
AB
Sensor, switch Engine control module (ECM) Actuator
NOTE
*1: California 

GENERAL DESCRIPTION
MULTIPORT FUEL SYSTEM (MFI)13A-4
Control System Diagram
AK604117
Fuel level
sensorFuel tank Air
inlet
2  Exhaust engine
    oil control valve
1  Intake engine
    oil control valve4  Manifold absolute pressure sensor
2  Intake air
    temperature sensor
1  Mass airflow sensor
6  Intake
    camshaft
    position
    sensor
7  Exhaust
    camshaft
    position
    sensor
3  Throttle position
    sensor (main/sub)
5  Evaporative emission
    purge solenoid
3  Throttle actuator
    control motor
12  Fuel tank differential
      pressure sensor
13  Fuel tank
      temperature
      sensor10  Heated oxygen sensor (front)
11  Heated oxygen
      sensor (rear)
8  Crankshaft position sensor5  Engine coolant
    temperature sensor
9  Knock sensor
4  Injector
Fuel pump Fuel pressure
regulator Evaporative
emission
canister
6  Evaporative
    emission
    ventilation
    solenoid
1   Mass airflow sensor
2   Intake air temperature sensor
3   Throttle position sensor (main/sub)
4   Manifold absolute pressure sensor
5   Engine coolant temperature sensor
6   Intake camshaft position sensor
7   Exhaust camshaft position sensor
8   Crankshaft position sensor
9   Knock sensor
10 Heated oxygen sensor (front)
11 Heated oxygen sensor (rear)
12 Fuel tank differential pressure sensor
13 Fuel tank temperature sensor
     Ignition switch-IG
     Ignition switch-ST
     Power supply
     CAN communication (input signal)1   Intake engine oil control valve
2   Exhaust engine oil control valve
3   Throttle actuator control motor
4   Injector
5   Evaporative emission purge solenoid
6   Evaporative emission ventilation
     solenoid
     Ignition coil, ignition power transistor
     Multiport fuel injection (MFI) relay
     Fuel pump relay
     Starter relay
     Throttle actuator control motor relay
     Generator G terminal
     Heated oxygen sensor heater
     A/C compressor relay
     Diagnostic output
     CAN communication (output signal) SenseAct
     Engine oil pressure switch
     Power steering pressure switch
     Generator FR terminal
     Generator L terminal
     Vehicle speed sensor 
Decide
ECM
(with barometric
pressure sensor)
AB