I have a 2008 S80 T6 - 110,000 miles on it, owned for ~6 yrs so I know the car. Been perfect until now. Seems when I depress accelerator more then say 15%, I don't get additional acceleration, and in fact the acceleration is reduced vs just a very light throttle increase. Another clue - I can hear the turbo much more now. While it does sound sort of cool, its the acceleration I want, not a louder turbo. It almost seems as if the turbo spools and is dumping boost rather than directing into the engine. But also it sounds like it does not spool up to as high of a pitch as when running correctly, where I could barely hear it's high pitched whine before it got out of my audible range.

No codes, regular services at dealer, not abused in any way, all stock, etc. Any ideas?

 

No ideas? I'm going to take it into the dealer, just not in a hurry to do so. But I'd like to be informed when I go in, otherwise they will not likely know the root cause and start replacing expensive parts on me. Seen this with my turbo Saab Aero a long time ago, many parts replaced and several $k later finally found a small inexpensive part that actually fixed things.

 

Update: Resolved! Thought I'd post the solution here. Turns out to be excessive knocking. Started this spring when the AC compressor was turning on more often, loading up the engine a bit more. Got worse throughout the summer. I've only been running 93 octane gas. Gas formula seems to play a part here also, some say summer gas is worse. idk? Anyway, my independent mechanic cleaned the throttle body and replaced the plugs and the ping went away, and my power has returned!