The other day I put a stage 1 tune on my Audi a6 2.7t. I have forge splitters adjusted at about 25 clicks.

When I take off it will spike to 15psi and then I hear a Pshhh coming from under the hood(not the splitter valve noise), then it runs at 6 or 7psi. It runs great but I should be able to stay at the 15psi though. It only happens on the first "launch" though. After that I cannot get it up to 15 again, it will only stay at 7. If I turn my car off and then back on I can spike to 15 again, but just once. What do you think the problem can be?

I looked for cracked hoses and I tightened all clamps. I took the hose off the n75 to see if that was bad but it wasn't.

I'm stumped here guys, I'm new to turbos but I have done a lot of searching and couldn't find a solution or even similar problem. Any input is much appreciated.

 

Have the computer scanned for pending codes and do a vacuum check - you may have a boost sense problem or a vacuum leak.

 

I scanned it with vcds and I got a p1557 code. That's most likely a boost leak right? Or could it still be a n75 valve?
Going to do a pressure test this week and see if I can find any leaks.

 

Did a pressure test and there was a long slit on my TBB. Just got a new one and im running 16psi now.