Hi - I have a 1999 523i with the auto gearbox (5 speed tiptronic).
Just recently it does not like changing up when under harder acceleration. It will operate fine if just tootling around but as soon as I up the pace it accelerates to the redline but refuses to change up. I can still change up using the tiptronic mode.
The auto change in sports mode is equally troublesome.
The car has done 102,000 miles with the usual full service. No warning lights have ever come on - it was suggested that it could be related to the ABS sensor!!
HELP PLEASE