Mine started out of the blue. I have had the car for about 5 months and the problem started happening at about 1.5 months into my ownership. I was stupid and didn't buy the warrenty. How many miles do you have on your X? I have about 106,000 right now and it started around 97,000.

74K on my car right now, started happening around 72-73K, relatively recently

2001 X5 4.4 ltr 105000 miles.

I have chased this problem also. I can say what it isn't. Fuel pressures good @ 50 PSI, Crank position sensor good, Cam position sensors are good, no OBDII codes at all. Cleaned the battery cable conections @ the battery.

I most recently cleaned the power lug on the drivers side of the fire wall under the hood. It wasn't corroded but it looked glazed. I disassembled it and cleaned both sides. Knock on wood, it hasn't happened again since.

Have you had a fuel system flush? I had one a little after it started happening and it didn't really help. A Motorvac if it matters.

One poster on Bimmerforums at http://forums.bimmerforums.com/forum...=1#post7238767 said that his 06 4.4 had this problem and his service department replaced all of his injectors and the problem went away. I just posted there to see if it stayed away.

I would think that the fuel system flush should have cleaned the fuel injectors well enough that if that was the problem it would have been fixed.

Thanks for the info on what it isn't, I was thinking of throwing cam speed sensors at it. Well now i can save that money for something not on your list.

I have run Lucas Oil's fuel treatment (and injector cleaner) through a few tank fulls (about 60 gallons of gas). It only requires 3 oz. for every ten gallons and it comes in a quart bottle. It is possible that it has finally cleaned the injectors curing the problem.

It just seams too suspicious to me that as soon as I cleaned the power lug on the firewall the problem hasn't come back. I think the lug that I'm talking about feeds power to the computer (and many other things) and is a very long run from the battery. Any little interruption could cause these symptoms.

Just to make sure I just went down and started it. Still no problem. Fingers crossed

I just read the other link in your previous post. It may very well have something to do with the brand of gas or individual gas station. I have been filling up at a local Hess Station (cheap gas). My most recent fill up was at a Mobil Station near the highway. More to follow.

I only run premium from shel and chevron. Mostly Shell because I have a company gas card from there.

Techron made a big difference for me. Do you all rec. a gas treatment in mine at current 7000 miles?

The Fuel system flush that I had may have been an underlying reason that my cats got clogged up. I ended up cutting them down and hollowing them out and am working on getting an O2 sensor simulator that will get rid of my SES light. (keep getting an after cat O2 sensor aging errors, sim is to slow.) Cats are just too expensive and since there are two it is even worse.

If you are having the starting problem like I am having, but you only have 7000 miles on your X5 I would make the dealer or BMW NA fix it. Not worth throwing your own money at.

I am starting to think you have a fuel line check valve problem. The fuel filter has the pressure regulator built in and when the one way valve is leaking it allows the pressurized fuel line to get air in it The fuel in the lines runs back into the tank and delay or even make difficult starting. That situation is not monitored by OBD so that would explain the lack of SES. If you can, stick a fuel pressure gauge on the fuel rail and let it sit overnight and see if the pressure holds.