Anyone noticed Their X5 has multiple personalities?
 

After quite a few years of owning this thing I have noticed this truck is quite temperamental. It has days where is roars to life full of zeal and ready to roll, other days it starts and just kinda moves and goes. There are some times when I am driving into work and think, what a nice day driving in. Pleasureable, the truck is responsive and peppy, then there are times when its just like a chore where its tired and wants to stay in bed. I don't know if its me or if its just gotten fussier in its old age.

I have never noticed this with the other BMW's I've owned, just this one. Even the 528....its just under 90k and been exactly the same since the day I bought it 5 years ago with 12k miles.

I was having similar issues for the past month or two - turns how my red boost hose clamp and come undo - fixed that and now it rips again.

Just a note made - check the red boost hose and look for vacuum line issues.

did you get any codes while the hose was off?

No codes - you can just feel the difference. Not as aggressive as the truck normally is

I am not a twin turbo model. I am however searching for a vacuum leak.

I find the automatic 4x4 system is one of several things that make performance and smoothness inconsistent. Each time you start your X5, the transfer case calibrates the clutches that send power to the front axle. In my opinion, the degree of lock up of the clutches varies each time you restart the vehicle. If the clutches lock up more than expected, the drive train will bind up a small amount which can add drag. The ECU senses this and then tells the engine to limit torque. If the clutches get bad enough, you actually will get jerking and rough shifts.

As a test disconnect your transfer case at the module. Pre LCI put this in the back by the battery. Remove the cover on your battery and you will see a silver box with ATC700 on it. Unplug and go for a drive. Be careful as stability control and ABS are disabled.

Interesting. Is the clutch calibration the only 'electronic' function that the transfer case does? In other words,
Does disconnecting that module ONLY impact the clutch calibration and nothing else?

I asked my dealer that very question and they were unsure of the answer. Disconnecting the transfer case also disables the stability control and ABS so there could be other affects.

If it is a Kia i may agree on this statement. But BMW must have more sophisticated system to do the calibration. Actually if the calibration is done once in a while such effect may occur, hence it is done at every start-up, to compensate for changing conditions. Also there is absolutely no reason for "binding" if ,let's say 10% of the torque is sent to the front wheels instead of 0%. This is not a low range system of diff locking. Also if the engine goes in a limp mode it will be a very noticeable reduction in the power, not a variation of the power.