I have a 1988 GTU. It recently started making a noise that sounds something like a leaking/purging line after 5k all the way to redline. The temperature remains constant and oil pressure is normal and it doesn't affect the performance either. What could this be? I will drive my car under 3k until I get this figured out.

 

Ive checked and nothing is leaking...what could this be?

 

Do you still have the stock cats? IF so check for leaks or hollow the first 2 out.

 

that would also explain why the 4th and 6th ports dont always actuate/actuate weird on my stock s4.

 

To better describe the sound and get more responses, it is a hissing sound. My friend joked around and said its my "nos" I will jack it up and take a look at the piping tomorrow.

 

It sounds like its coming from behind the firewall on the drivers side. I know the airpump is on the other side, but ive been searching and it might be that the silencer hose popped off...the problem is I cant find it.

 

The problem comes and goes. I really want to fix it so I wont have to worry about it anymore. Does anyone have any suggestions of what it could be? I dont think its my cats, I looked under the car and they where all in tact and the heat shields where still on them. I didnt have time to actually remove them though. Could it have something to do with the air pump?

 

Is the silencer still installed on your ACV? Hell, is the ACV still installed?

 

My car is completely stock. I havent touched anything yet, and I know that the previous owners havent touched anything either. What could the ACV have to do with this?

 

Yes, everything is still installed in the car...it is COMPLETELY stock. Please help, I want to get back to "spirited driving"