engine MITSUBISHI ECLIPSE 1990 Service Manual

---- .~ _ _EMISSION CONTROL SYSTEMS
- Catalytic Converter I Air-fuel Mixture Ratio Control System25-9
,ATALYTlC CONVERTERRZXIAAAThe catalytic converter is installed on the middle ofand surrounded by a stainless steel shell.
the exhaust pipe under the floor.The catalytic converter oxidizes carbon monoxide
This catalytic converter uses a monolithic type
catalyst with a honeycomb structure that has itsand hydrocarbon, and reduces oxides of nitrogen.
surface coated with catalytic components. Thewhich are present in the exhaust gas, in order to
minimize their emission levels.
catalyst is supported by a stainless steel wire mesh
Exhaust air
3Stainlesssteei shell
\CoverStainless steel wire mesh
lEM0031
AIR-FUEL MIXTURE RATIO CONTROL
SYSTEMThe
MPI system is a system which employs the signals from
the oxygen sensor to activate and control the injector installed
at the each cylinder head thus precisely regulating the air-fuel
mixture ratio and reducing emissions,
This in turn allows the engine to produce exhaust gases of the
proper composition to permit the use of a three-way catalytic
converter. The three-way catalytic converter is designed to
convert the three pollutants
(1) hydrocarbons (HC), (2) carbon
monoxide (CO), and
(3) oxides of Nitrogen (NOx) into harmiess
substances.There are two operating modes in the
MPI system:
(1) Open Loop
Air-fuel ratio is controlled by information programmed into
the engine control unit at manufacture.
(2) Closed Loop
Air-fuel ratio is varied by the engine control unit based on
information supplied by the oxygen sensor.
NOTEFor detailed information concerning the
MPI system, refer
to Fuel System.

__..--. -._ _^__. __--- -._ _..EMISSION CONTROL SYSTEMS
- Evaporative Emission Control Svsvem25-l 1
,VAPORATlVE EMISSION CON-
TROL SYSTEMIn order to prevent the escape of fuel vapor from the
fuel system into the atmosphere. the evaporative
emission control system consists of a charcoal
canister, a purge control solenoid valve, etc.
When the fuel vapors generated inside the fuel tank
fill the tank, they press and open the overfill limiter’s
valve and pass to the canister, where they are
absorbed into and accumulated by the charcoal.
Because the purge control solenoid valve is ON
(open) when the engine is running, as a
conse-
Non-TurboAir cleaner
Fuel injector
Canister
Charcoal
/Purge control tsolenoid valve r
RZSGAAB
quence of the purge air being taken in from the
canister in accordance with the intake negative
pressure (vacuum), the fuel vapors accumulated in
the canister are taken from the charcoal and are alsotaken into the intake manifold.
Note that the purge control solenoid valve is OFF
(closed) when the engine is cold and during idling,
and so fuel vapors are not taken into the intake
manifold at that time.
Overfill
limiter(Two-way valve)
Fuel check valveFilter
- Fuel vapor
*---- Purge air

25-12EMISSION CONTROL SYSTEMS- Evaporative Emisson Control System-
TurboPurge control valve
/Air cleaner
Canister
-Charcoal-ITurbo-
chargerPurge control
solenoid valve
Fuel check valve
Thermal expansion
Fuel gauge unit
Filter
- Fuel vapor
- - - - Purge air
BEMO211
%-E?”solenoidvalve
Charcoal -fuel tank
CANISTERWhile the engine is inoperative, fuel vapors generated
insidEthe fuel tank are absorbed and stored in the canister.
When the engine is running, the fuel vapors absorbed in
thfcanister are drawn into the throttle body through the
purgecontrol solenoid valve.
Atmosphere
L- Filter03Roo3E

EMISSION CONTROL SYSTEMS- Evaporative Emission Control System25-13
IFrom canister1
,To intake air plenum or throttle body
7EMOlPControl
relavPurge control
solenoid valve
Battery
g
6
,zEngine control
unit
From throttle body
4To purge
control
valve
SEMo2laControl relay
3:
1.
Purge control
solenoid valve
zBattery g
Engtne controlunii
bfuo532JPURGE CONTROL SOLENOID VALVE Turbo>
The purge-control solenoid valve is the ON/OFF control type of
solenoid valve; it functions to control the introduction of purge
air to the intake air plenum from the canister.
PURGE CONTROL SOLENOID VALVE
The purge-control solenoid valve is the ON/OFF control type of
solenoid valve; it functions to control the activation of the
purge-control valve.
ITo throttle body11PURGE CONTROL VALVE
The purge-control valve functions to control the introduction of
purge air to the air-intake hose from the canister.
0 From canister