A hydrocarbon adsorber and a thermoplastic resin combined and formed to a porous scavenger for insertion into the air intake system of a motor vehicle engine. The resulting porous scavenger adsorbs volatile hydrocarbon molecules from raw fuel remaining in the air intake when the engine is shut off. The adsorbed molecules are then stripped or purged from the scavenger and reintroduced into the air intake when the engine is next started.