HYDROCARBON ABSORBING AIR FILTER BOX

A hydrocarbon absorbing air filter box is provided for absorbing evaporative hydrocarbon emissions from an air intake duct of an internal combustion engine. A combined mass airflow sensor and hydrocarbon trap comprising the hydrocarbon absorbing air filter box includes a duct supporting a hydrocarbon absorbing sheet within an interior of a housing. The duct communicates an airstream from an air filter to the air intake duct during operation of the internal combustion engine. An opening in the housing receives a mass airflow sensor into the duct, such that the mass airflow sensor is disposed within the airstream. Guide vanes extending across the duct reduce air turbulence within the airstream passing by the mass airflow sensor. Ports disposed along the duct allow the evaporative hydrocarbon emissions to be drawn into the interior and arrested by the hydrocarbon absorbing sheet when the internal combustion engine is not operating.