System Application - Subaru SVX 1992 Manual

2-1 (01001
EMISSION CONTROL SYSTEM AND VACUUM FITTING
1 . System Application
There are three emission control systems which are as
follows :
1) Crankcase emission control system
2) Exhaust emission control system
Three-way catalyst system
" A/F control system
Ignition control system
EGR system
3) Evaporative emission control system
4) Fuel pump discharge flow control system
Item
Main components Function
Draws blow-by gas into intake manifold from crankcase
Crankcase emission control system PCV valve
and burns it together with air-fuel mixture . Amount of
blow-by gas to be drawn in is controlled by intake man-
ifold pressure.
Front (LH & RH)
Oxidizes HC and CO contained in exhaust gases as well
Catalyst system Three-way catalyst
Rear
as reducing NOx .
ECU (Electric
Receives input signals from various sensors, compares
control unit)
signals with stored data, and emits a signal for optimal
control of air-fuel mixture ratio.
A/F control system
Oz sensor 1 & 2 Detects density of oxygen contained exhaust gases .
Air flow sensor
Detects amount of intake air .
Throttle sensor Detects throttle position .
Receives various signals, compares signals with basic
ECU data stored in memory, and emits a signal for optimal
control of ignition timing .
Crank angle
sensor 1 & 2
Detects engine speed (Revolution) .
Exhaust emission
control system
Ignition control system
Cam angle sensor
Detects reference signal for combustion cylinder dis-
crimination .
Water temperature
Detects coolant temperature .
sensor
Knock sensor
Detects knocking in combustion chamber of each cylin-
der.
Receives various signals, compares signals with basic
ECU data stored in memory, and emits ON-OFF signal for
EGR solenoid valve .
EGR valve
Controls amount of exhaust gas to send to collector
EGR system
chamber .
BPT
Controls quantity of recirculation gas depending upon
engine operating conditions .
EGR solenoid Controls intake manifold pressure to transmit EGR valve
valve for ON-OFF signal emitted from ECU .
Absorbs evaporative gas which occurs in fuel tank
Canister
when engine stops, and sends it to combustion cham-
bers for a complete burn when engine is started . This
Evaporative emission control system
prevents HC from being discharged into atmosphere .
Purge control Receives a signal from ECU and controls purge of evap-
solenoid valve orative gas absorbed by canister .
ECU
Receives various signals, compares signals, and emits
i h fl l
ON-OFF signal for fuel pump modulator.
sc arge ow contro system Fuel pump d
Fuel pump Receives a signal from ECU and controls the discharge
modulator flow of fuel pump.
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