Hi, I have a 2001 320i and had the same problem about 6 months ago, took 3 mechanics before it was fixed, it was a camshaft sensor problem, the 2nd mechanic had it on a scanner but nothing showed, I know nothing but I think his scanner wasn,t hi tech enough for a BEMA!!! HaHa, Anyway, good luck with that, I know how frustrating that problem is!!