hi i have been having this problem with my 2007 2.0 tdi 170 for a while. The car starts to hessitate and splutter at about 3000rpm then goes into limp home mode the engine management light comes on sometimes but mostly it is the glow plug light flashes, you have to pull over switch off and restart to sort it, this happens every few hundred miles or so inbetween the car runs fine. I had it diagnosed at audi they told me to replace the turbo but the problem is still there, i am aware of a smell coming from the car when this happens it is like a brake binding smell but brakes are ok, sometimes when i start the car the engine won't rev above 3000rpm for the first few times then clears and revs freely. Any ideas as to what may be the problem. thanks.