Gear Slip / Transmission Slip
 

I have a 2001 X5. Yesterday I was driving along without any problems on the highway. Then the highway started to take me up hill. In order to maintain the speed limit while going uphill I had to "put the pedal to the metal" if you will. During the acceleration everything was going fine and then all of the sudden it decreased in power but my RPM's shot through the roof. It sounded like my transmission missed the gear or something. I let off the gas for the RPM's to come down and then gave it a little gas and it seemed to shift into the appropriate gear it needed to finish climbing the hill. Since then it seems to happen only when I accelerate quickly (i.e. entering the freeway or climbing a hill). My first thought was to add some transmission fluid and that would fix the problem but after reading some posts it looks like it has a lifetime transmission fluid that never needs to be changed. (hard to believe) Anyhow, it seems to work a lot better when I switch over to manual shifting. However, that is starting to slip too. I am not going to drive it anymore until I figure out what might be wrong. So any help would be greatly appreciated. I have experience fixing cars so if I can avoid taking it in to a BMW dealer to save some $$$$ and fix it myself as I have been hit hard by this economy. So any help or advice would be greatly appreciated. Thank you!

If u have the experience than you should try to rebuild your tranny or buy one that is already rebuild and replace it yourself it is really not difficult if u have the right tools...
changing the fluid might also help...I have done the same thing 20k miles ago..and mine shifts much smoother now...but at some point it will let go completely then the 'real' work will start

Hope everything will work out...keep us posted ;)

:xoutpost: it is possible that you hit the kickdown switch which changes down gear and allows engine to go to max rpm .try it again and see what rpm it begins to seem to lose power then press gas to floor and see what happens . sometimes the engine management goes into a lazy mode and when power is needed to climb hills the transmission can do strange things . also you can reset transmission by turning ignition on to position 2 so all instrument lights on then press gas pedal as far as it goes for 30 seconds then release gas pedal and start engine .
and if you need to rebuild transmission then swissfrank has posted photos and instructions on this forum , keep us up to date on issue and good luck .

Guys, I'm having the same problem starting today. Gear change seems to be fine, the problem only happens on kickdown. Will try the amacman suggested. It seems to be either a transmission problem or the turbo is cutting out (I have a 2003 3.0D)?! Thanks.

could be electric problem so try diagnostics
camshaft or crankshaft position sensors can cause those problems
leaking air intake can also cause same problem on diesel

All, thanks for your help. For the time being acacman's 30 sec reset has seemed to have worked!

Yup, this worked for me in the past too...my problem was a harsh 2-1 downshift.