Patent ID: 6932068

Claim:
An evaporative emission control system including a canister for collecting fuel vapor flowing from a fuel tank, comprising: a purge control valve that controls a degree of fluid communication between the canister and an intake passage of an internal combustion engine; a failure determining unit that determines a failure of the purge control valve; a purging unit that executes a purging process by opening the purge control valve so that purge gas flows from the canister to the intake passage; a fuel concentration learning unit that executes a learning process for learning a fuel concentration of the purge gas to provide a learned value of the fuel concentration; a fuel injection amount correcting unit that executes a correcting process for correcting an amount of fuel injected into the internal combustion engine based on the learned value of the fuel concentration; a purge condition determining unit that determines whether at least one condition for execution of purge control is satisfied; a normal process requesting unit that requests execution of the purging process, the learning process and the correcting process when the purge control valve is normal and the at least one condition for execution of purge control is satisfied; and an open-failure-mode process requesting unit that always requests execution of the learning process and the correcting process when the failure determining unit determines that an open failure occurs in the purge control valve, the open failure being detected when the purge control valve is stuck in an open state.