Weak/stumble start up

[BMWLOVER]

Hey gang,

I've recently been noticing more and more how weak the x5 starts when I first start it. (so on cold start up). It's always garage parked and its not cold out at all so I'm curious as to why it does this. Before it used to fire up and pretty much growl on start up. Now it starts up sounding like its gonna die.

Also recently I was turning right at an intersection and I gave it a little throttle to move forward then quickly pressed the brake and it stalled. No error codes or anything like that. I started it up and it drove off fine.

SUMMARY- Very weak start up almost like its going to die. But the rpms quickly get to normal and it idles fine.

Stalled the other day while turning right. I applied little throttle then immediately let off and put the brakes on and it stalled. Can not seem to recreate this.

Its got 94k KM ( 58750 Miles) and I have not changed spark plugs.

Any ideas and help will be appreciated. Thank you so much!

[Big "J"]

Camshaft position sensors have generally been the culprit for stalling. Rough start could be many things including bad gas, clogged fuel filter or dirty fuel injectors.
Check simple things first and go from there.

Good luck!

[BMWLOVER]

Are the cam shaft position sensors easy to replace, or will I be better off taking it to a mechanic? (considering I don't have too much practice working on BMW's)

I'm planning on changing my fuel filter very soon hopefully that helps. I have noticed that before I would turn the ignition on and wait until the beeping would stop and then start the x and it would fire up nicely. Recently however even if I wait before starting it starts up rough. This only happens during a cold start (usually the first start in the morning).

[Capinsatchell]

Any update on this? I'm getting the same thing with the weather turning cold...

[bcredliner]

I suggest checking for fault codes and see if the computer knows what is going on.

[subieworx]

I was having similar issues with my 04 4.4 with 93000 miles. Replaced the spark plugs and now all is well.

[upallnight]

Could be the seal between the DISA valve and intake manifold. Cold weather could cause the seal to shrink enough that now you have a vacuum leak. Just fixed my P0171 and P0174 error codes (lean bank 1 and 2). Originally I took the DISA valve off the intake manifold but the valve wasn't rattling and the test for vacuum for the flap WAS O.K. SO I put it back on, but I was still getting the Service Engine Soon (SES) light. One cause for cause for the SES is a vacuum leak and since I didn't have a smoke machine I decided to use what I did when I use to race Triumph and Lotus in the 70's and 80's. I made a tool to listen for vacuum leak. The tool consisted of a funnel and a length of hose. I connected one end of the hose to the funnel and use the other end of the hose I use to probe around the engine compartment. I held the funnel to my ear and listen for vacuum leaks at all the known places. When I placed the hose by the intake manifold and disa valve I heard the vacuum leak.

Removed the DISA valve and noted that it came off fairly easily (another sign of a flattened seal). I removed the old seal (why BMW engineers didn't use a standard O-ring for this application I would never know) with a pick, jeweler screw drivers and a brass brush (don't use a steel brush), if you don't have a brass brush, use an old tooth brush.

Fitted an O-ring (62mm x 55 mm x 3.5mm) to the DISA valve and when I went to install the DISA valve it took a little more force to to push it into the intake manifold. Started the engine and clear the previous SES. Went for a drive and a fill up and check for fault codes on my son's tablet with the Torque App. NO fault code found. Look at the Long Term Fuel trim and it was within the guideline. The idle was rock steady at 700 rpm.

Hope this help you.

[racebmwm3]

I have a similar problem.

In my attempt to find the location of some leaking fuel, I was led to a leaky fuel return line hose on the left lobe of the tank. Hoping this is the reason.

Also, why the heck is this fuel filter on this truck sooo pricey? It's like $100.

[upallnight]

It not just a fuel filter, it's also the fuel regulator.

[racebmwm3]

Originally Posted by upallnight

It not just a fuel filter, it's also the fuel regulator.

Yep, I realize that now...