Well I have the tfsi in my A4 b8 and I have just spent. Small fortune trying to sort out an intermittent idle judder. Did the decoke, full service, full diagnostics. Everything. No fault codes, no recorded misfires.
So the shop got a very complex vibration meter in it. Turns out that its the standard mapped idle fuelling strategy for this engine. Some do it more than other. Mine judders the seat and has had me pi**ed of now for over a year. Si I decided to tackle it or ell the darn thing.
So, that's what it is. To prove the theory we then hooked up a mk5 gti to the same vibration meter. On the graph the exact same trace came up. And it could be felt in the cabin too, although less intense presumably cos its transverse.
Anyway, thats it. So until VWAG come up with a patch you re probably stuck with it. Or sell it............