U know I own 2 BMW a 745 and a x54.8is and before I found my friend I went to don Jacobs and they really pissed me off. They are thieves and all there parts are above the original BMW list price. I order my parts from a BMW dealership in Ohio and I save so much money. I am a dealer to so I get a little discount. If u ever need any parts or after ur Cpo is finished, u need a good reliable mechanic don't hesitate to email me. I can have same quality work done by a professional that has all the tools the BMW has. He is actually has friends over there at BMW and I believe I have heard about ur x5 is it silver?
The valvetronic is where u have random misfires because ur engine is running right which cause the valves not to fire right. It's a big job and it requires alot of parts I read technical service bulletin on it and I can email it to u if u want. The reason I'm not sure if that's what's wrong with mine is because I have no check engine light. I'm getting a really weird noise from the bottom on hard accelerations. But if I drive really smooth it is not noticeable. Also when first turned on in the morning it vibrates really hard for the first ten min or so. Is that the same issues u are having?