Hey guys I just recently got back into a seven after a short break. I'm glad to be back and recently acquired a bone stock S4 T2 with roughly 110k original miles.

I'm having trouble chasing down a driveability issue. When I start her up in the morning the car runs fine. builds boost great and drive normal. After sitting during the day and I go to lunch at work, the car drives normally just with no boost. I can hear the turbo a little bit and the stock boost gauge only goes a little above zero and the car will not go passed 5500 rpm. This will continue until it sits for a while. Sometimes it may not go away after sitting and may persist.

Like I said though, sometimes it runs fine and revs all the way up with full boost and runs awesome. I was told the s4's dont use a boost solenoid and the ecm doesn't control boost pressure electronically. Any help or insight would be greatly appreciated! Thanks guys

 

checked to see if it was a plugged cat, found the main cat split in the middle not enough to cause my concern drove it with the cat removed anyways with no change. vacuum at idle improved a little bit, at a steady idle around 800 i've got 15 inches of vacuum at around sea level