Evaporative Emission (EVAP) Canister Purge
Volume Control Valve (Circuit)
SYSTEM DESCRIPTION
Camshaft position sensor
E
Engine speed
ECM
E
EVAP canister
purge volume
control valve
Mass air flow sensor
E
Amount of intake air
Engine coolant temperature sen-
sor
E
Engine coolant temperature
Ignition switch
E
Start signal
Throttle position sensor
E
Throttle position
Heated oxygen sensor 1 (front)
E
Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel tank temperature sensor
E
Fuel temperature in fuel tank
Vehicle speed sensor
E
Vehicle speed
This system controls flow rate of fuel vapor from the EVAP canister. The opening of the vapor by-pass pas-
sage in the EVAP canister purge volume control valve changes to control the flow rate. A built-in step motor
moves the valve in steps corresponding to the ECM output pulses. The opening of the valve varies for opti-
mum engine control. The optimum value stored in the ECM is determined by considering various engine con-
ditions. When the engine is operating, the flow rate of fuel vapor from the EVAP canister is regulated as the
air flow changes.
SEF249P
COMPONENT DESCRIPTION
The EVAP canister purge volume control valve uses a step motor
to control the flow rate of fuel vapor from the EVAP canister. This
motor has four winding phases. It operates according to the output
pulse signal of the ECM. Two windings are turned ON and OFF in
sequence. Each time an ON pulse is issued, the valve opens or
closes, changing the flow rate. When no change in the flow rate is
needed, the ECM does not issue the pulse signal. A certain volt-
age signal is issued so that the valve remains at that particular
opening.
GI
MA
EM
LC
FE
AT
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0443
EC-309