Methods and systems are provided for operating an engine having a hydrocarbon retaining system and an emission control device coupled to an engine exhaust, the engine exhaust comprising a venturi. One example method comprises, during a storing condition, routing exhaust gas through the venturi without generating a venturi action, and then to the hydrocarbon retaining system, while bypassing the emission control device, to store hydrocarbons in the hydrocarbon retaining system, and during a purging condition, routing exhaust gas through the venturi while generating venturi action, then to the emission control device, and then to the hydrocarbon retaining system, to purge stored hydrocarbons, wherein a flow of purged hydrocarbons is drawn back to the venturi via venturi action.