My Civic wasn't idling. If I let off gas, it died.

I pulled off the IAC and sprayed it out with brake cleaner. There was some gunk inside (gummy/sticky substance). Put it back together and the car was still idling really low, but not stalling. I ran the car this morning, and it's idling perfectly, but the hiss is still there.

I'm sure I have a vacuum leak now, as I hear a hiss for about 10 seconds after I stop the engine. I have located the general vicinity of the leak to the area I was working (IAC/manifold). I may have cracked or loosened a hose. I would like to know if there is supposed to be a seal between the IAC and the intake manifold? As far as I know there wasn't one on mine. Is it possible the leak could be there?

 

Thread titles MUST summarize the tech problem -- edited.

A vacuum leak would cause a high or surging idle problem, so consider other possibilities for the noise.

 

i agree. bump bump