Hi, I've recently bought a '97 528 auto, with 73K on the clock, and have noticed it sometimes loses power. It also stalled on me yeterday, twice, whist in stop start traffic. No engine warning lights come on, and if I stop the car, stop the engine and then restart the car, it return to 'full-power'. To me it seems like the engine is switching to 'safe mode', but isn't telling me about it.

Anyone with any ideas?

Have you checked if the block has been changed.  BMW had some issues with the soft "Nikasil" lining in the 523 & 528 (not sure about 520) manufactured before 1998.  Apparently the high sulphur content of UK petrol affected the Nikasil cylinder lining.  If you do a search for Nikasil on the Forum you will find some more knowledgeable posts on the subject.

I can tell you that your 528 is from the period when Niksail was a problem (1996 - 1998 ??)

I have a 96 523i which has experienced exactly the same problems. It was diagnosed as a faulty O2 sensor, which then turned out to be the vanos unit malfunctioning which messes up all the timings. I've also been told this can knacker up the Catalytic converter if it goes on to long.

All in it's cost me about £600 from a specialist (although I have a Motoplan warranty that had to have their arms twisted to pay 75%).

If it was the Niksail problem you would experience very rough idling and a high throughput of oil.

Good Luck!!

Well, it was't the Nikasil problem, it was a faulty crank sensor. All fixed for £101, which is being covered by the warrenty I got with the car.

Great service from the local main dealer, Godfrey Hall in Coventry as well, so I'm happy!