The main element of this system is a carbon filter located in the engine compartment.
At idle, when the engine has not yet warmed up, fuel vapors added to the balanced mixture cause excessive emission of toxic substances through the exhaust pipe. Because of this, one of the chambers in the throttle body of the fuel injection system is used to direct fuel vapor to the filter only after the throttle valve is opened wider than in the idle position. If there is no vacuum, the filter purge valve will not open.
On a cold engine, air and fuel supply is limited by a thermal valve.
When the filter purge valve is opened, air is sucked in under a slight vacuum from the air intake. In the event that operational problems occur during engine warm-up, and all settings and adjustments of the main fuel system and the engine are carried out correctly, the operation of the thermal valve should be checked.