Fuel Evaporation System: Operation
When engine coolant temperature rises above 129°F (54°C), a bi-metalic vacuum switching valve (BVSV) opens purge line between canister and throttle purge port. As engine speed increases to a moderate level, throttle valve opens purge port to manifold vacuum and canister vapor flows through purge line and into combustion chambers for burning. As engine speed drops to idle, the throttle valve closes off purge port to manifold vacuum and canister purging stops.
Celica GT-S uses a restrictor in the purge line to control the amount of vapor flow admitted to the combustion chambers.