Here's something interesting I found after installing my Frankencar midpipe.

Whenever I turn on the AC, the intake noise at the cone (the hiss) gets REALLY loud. I thought, the idle increased, so it got louder. But with the AC off and revving up the engine I do not get the same hiss. Only with the AC on!

My conclusion is that one of the lines hooked up the midpipe is involved with the AC in some way. Perhaps a vacuum issue? I dunno. I just hope its not dangerous! Does anyone know EXACTLY what the three lines going into the midpipe (formerly the resonator) do? One is crankcase breather line, but what are the other two? I'd look it up in the FSM but I don't have it with me here.

Anyone else with Frankencar please confirm this. Let your car warm up and idle. Then turn on the AC and listen to the intake cone hiss. Does it get much louder?

 

I was using the AC today.... i didn't notice any sounds outta the ordinary.. i will try it w/ the hood up and listen to the intake and see wattup. I believe the major sounds come from the autos.... i'm a 5spd so i dunno. I'll try tomorrow and get back to this post.

 

Thanks yeah I have the autotragic. I didn't notice the sound until I had my stereo off then it was quite noticeable. I checked the three lines going into the midpipe, they were all tight and secure. I am just wondering if anyone else heard this strange increase in hiss with the AC on. I'm not worried its a problem, but rather I just want to know how the three hoses are involved in the AC, since I don't think an increase in idle speed can explain the increased hiss.

 

i got the same loud hissing sound when AC turned on and was wondering the same thing.

 

pretty shure its normal for autos to have louder hissing than 5spds. I listened to a 5sp with a hybrid and it did not hiss much at all compared to an auto

 

i got that sound too,are you auto too,

 

Ok at least I know everyone else gets it too. I am also auto. I'll crack open the shop manual (left it at my other house, so I won't have it for a week) and try to figure out why the hissing noise is so loud.

 

I don't have this problem, but then I hardly use my A/C ha ha.

 

bump...