# Loud Hissing Sound from back of engine near firewall - help



## don_rapheal (Apr 5, 2004)

Hey 4titude friends,

Need an assist on this one. Here is the lead in:

In an effort to pass smog, I was replacing a couple of suspect vacuum hoses on my 2001 Audi A6q 2.8L. One of the lines I replaced let out a hiss sound, nothing unusual, right? I finish up and go to start the car and next thing I know, I hear this loud hissing sound from the back of the engine near the firewall. I inspected the vacuum line that I had installed and all other lines, but couldn't narrow it down there. I proceeded with removing most of the air intake housing components to see if that helped with anything. It sounds pretty loud - I am thinking of running a smoke test or something (IDK) to narrow it down.

I am so confused what exactly it could be. It is pretty loud, I just am at a lost. Anyone's input is appreciated. Thanks.


----------



## don_rapheal (Apr 5, 2004)

So I was attempting to run a "Set Readiness" to check if anything I did would be related to air or exhaust; however, I was unable to complete the test. What I learned was that I could not keep the RPMs at a constant rate. Once I tried to stabilize the RPMs by letting off of the gas, the RMPs would drop significantly. Please help. I'll do some searches, but just wanted to give an update.


----------

