Reduction of HC emissions for vapor recovery purge systems

摘要

An apparatus and a method for controlling hydrocarbon emission from an internal combustion engine having an air/fuel intake coupled to a fuel vapor recovery system. Fuel vapors are periodically purged from the fuel vapor recovery system into the air/fuel intake. The mixture of air/fuel vapor and fuel is regulated by a feedback loop response to an exhaust gas oxygen sensor to maintain a desired air/fuel ratio. At the beginning of each purge cycle, engine spark timing is temporarily retarded to reduce hydrocarbon emissions during the response time of the feedback loop.