Method and apparatus for controlling fuel vapor, method and apparatus for diagnosing fuel vapor control apparatus and method and apparatus for controlling air-fuel ratio

摘要

Purge control valves are mounted to purge pipings arranged in parallel for supplying purge gas from a canister to an engine. A flow rate of the purge control valve having a larger flow rate size is controlled in a step mode, and a flow rate equal to or smaller than a variation quantity in said step mode is controlled by the purge control valve having a smaller flow rate size.