2000 S4 - Low Boost and Rough Idle!!

[RauppMan]

So i just bought a 2000 S4, the car looks and runs great. It has 115k miles and is stock for the most part, turbos replaced at 60k, and it does have an AWE boost gauge installed so i cant help but notice that even when im accelerating hard its only reading about 6lbs of boost and i cant help but think this is too low... also i have noticed that when i really get on it, not even redline but close, the car starts to run rough afterwards. The other day i was heading into work, did a hard run through the gears (not mashing it but still giving it the beans) and it took it fine but when i got to work a few minutes later it was sitting there for a second and started idling really rough. it would run good then cut out and you could watch the rpm gauge jump a couple hundred rpm's. it even stalled when i went to back into my spot (it cutout, i didnt stall it). then when i turned it back on it kept running rough and i even saw some blackish smoke coming from the exhaust for a minute. then after letting it sit at work for 4-5 hours i got back in and it ran fine... Same thing this morning on the way to school, ran great the whole way, did a hard highway run 5 minutes before i got here and it took it fine but when i parked, it started idling rough again so i just shut it off. Any help as to what is going on would be GREATLY appreciated! thanks!!

Oliver

[RauppMan]

I should also mention that the car is throwing no codes right now except the ABS light and thats only because one of the rear brake lines got a hole in it and is currently closed off. So besides that, the dash is clean and clear.

[LINDW4LL]

You should be at 8-10psi stock.

[obijohn22]

boost leak. pressure test, and test the DV's seperately

[RauppMan]

Okay so sorry it rook so long but I finally have an update (been busy with school) I pressure tested the intake system the other day, the only thing I could hear leaking eventually was the line going to my boost gauge... The wanker who installed it didn't use zip ties to secure the lines so I fixed that. Then from what I could hear it sounded like air was coming from the front right side of the motor, almost where the turbo is...(suppose it could be that rubber elbow in the boost hose?) It gets weirder, today I get in it and I'm driving along and I was hitting 5psi on gentle acceleration and on WOT I was reading around 13 psi! Then after I shut off the car and restarted it I was back to 5psi max... So confused! And also sad, here I thought it magically fixed itself.. I guess the next step is to test the DV's...

[ilyafil]

Limp mode? Mine used to do that. Sometimes I would get stock boost and sometimes only 5-6 PSI. Are you able to actually pressurize the intake? If so, how much pressure does it hold? Check spider hose. There's a check valve on it, sometimes it leaks boost into crank case. I deleted that line completely. Works great.