ok, I have a CAI and when I turn the AC on, the hiss of the CAI gets twice as loud at idle. It has been like this ever since I got a CAI but never thought anything of it but im just now wonderng if this is normal? For the Hiss to get really loud while the ac is on that is.

 

When you flip the A/C on your IAC Valve opens slightly to increase RPMs to compensate for engine load. You may also notice your RPMs increase by 100 or so. More load, slightly higher RPMs = more air needed = more hisssss.

I think it's normal.

 

ok thanks, It just seems really loud but I guess I can deal with it

 

its completley normal, i got the same noise. just thing is my windows are usually up when the a/c is on so i dont hear any hiss, but outside its a bit louder the normal. so dont worry about it.

 

Interesting you mention this because I get the same really loud hissing noise after I put in my frankencar midpipe, which is a similar design to the pipe for the CAI.

I think its normal, but you are right. It is a very very loud hiss, much louder than normal idle noise.