I did the IAC restrictor plate Saturday. I used the smaller of the 2 holes on the plate. Now I hear what sounds like a hissing sound coming from the IAC. I'm thinking its just trying to push air thru a small hole and that’s what’s causing the noise. I checked all my hoses and nothing is lose. Car runs fine and I noticed a small difference with the RPMs coming down faster with the plate on. So is the hissing noise normal with the plate installed?
