Thank you for the thread here... I think I have an idea now why my Scanguage isn't calibrating well: My MAF is failing, and thus, it's not reporting accurately, throwing the
SG's tracking off.
On the A4 (or MkIV) TDI engines, the MAF sensor is notorious for failing out. I know from the slight lack of power, that mine is failing out again. So, time to sleep, so I can book more hours at work, and buy a new MAF for my car :P