So I tried to do a search on this but, well, I didn't really know what to search for and "starting sound" didn't yield much. When I start my car after its been sitting I hear something that sounds like a whooosh, like something getting sucked into something (or blown out such as a loss of air clearing something). Its very loud and it seems to be coming from the driver side of the engine compartment, perhaps near the brake booster? Occasionally you don't get the sound if the car has been running recently but from cold I ALWAYS hear it and its very loud, much louder than the engine which is fairly loud itself. It only lasts for a second or two. I've tried to be as descriptive as possible, any ideas?