Help, x5 running strange

[culthero]

Thanks for all the great advice! I'll try a couple of those things, if I can't figure it out, I've got an appointment with a BMW tech next friday. I'll update when I get it figured out.

[culthero]

Originally Posted by weasel56

As while the idle control valve can act like a vacuum leak, the part you just described is the "DISA flap" and controls the variable intake runner legnth system. The idle control motor is the same one used in other BMW models, the lil silver can just above the throttle body.

culthero, also check the smaller branch of the intake boot to the throttle body/idle control, it has a habit of cracking in the turn giving unmetered air to the system. And check the "cyclone valve" crankcase vent valve. It is under the intake. With the engine running rough at idle, use a can of throttle body cleaner with the red tube and spray down areas you suspect for vacuum leaks, the engine will smooth out and idle higher when the leak is sprayed.

So is it #7 or #8 that I might need?

[Weasel]

#8 is the idle control motor... come to think of it, I'd might even have an extra one laying around in my toolbox. (probably was sticking from carbon and cleaned up back to full working order)

#7 is the DISA flap, which controls the variable intake runner length.

I would check the smaller hose on the throttle boot that goes to #8 as it tends to crack between the ridges on the outer radius of the turn... just stick your fingers back there and feel for splits in the hose. (one of many common likely causes)

[HelloWorld]

I have a misfire code before. I took it to the BMW service center.
They changed the MAF, doesn't help, they further change all spark plugs, no use.
Eventally, they replaced the coil and the breather valve, it fixed the problem.
Totally, it cost me US$2500 for something that could be fix with US$300

[culthero]

Originally Posted by weasel56

#8 is the idle control motor... come to think of it, I'd might even have an extra one laying around in my toolbox. (probably was sticking from carbon and cleaned up back to full working order)

#7 is the DISA flap, which controls the variable intake runner length.

I would check the smaller hose on the throttle boot that goes to #8 as it tends to crack between the ridges on the outer radius of the turn... just stick your fingers back there and feel for splits in the hose. (one of many common likely causes)

Can the DISA cause misfiring and the rough idle I am experiencing? X5 stalled when i let off the brakes and let it coast. Won't stall if completly stopped or driving, but still idles very rough at a stop.

[Weasel]

The disa flap should not cause the rough running/missfiring. It sounds like you have a big vacuum leak, most likely at the oil separater/crankcase vent valve. That is the one undder the intake manifold, towards the front... near the oil filter housing. Thats what the big plastic hose coming off of the front corner of your valve cover goes to under the intake.

When that part fails, it gives a big vacuum leak and burns more oil. With the engine running at idle, open the oil cap on the valve cover. It is supposed to have a slight vacuum, but if it feels like a vacuum cleaner is sucking on it... that narrows it down to just that oil separator cyclone valve.

[culthero]

First of, thanks so much for you help. It's really helping me narrow this down.


So I removed and cleaned DISA, it was ok, a lil bit of normal deposits on it, but it still had the rough idle once the engine got warmed up. Sprayed hoses around where you told me to do so and nothing.

At this point I"m assuming it can't be spark plugs or wires since when I turn the engine off, it starts up ok. It's after a little while of ideling that the rough shaking begins. Hope I'm right?

I also did what you said by removing the oil filler cap while it at a rough idle. Well, it had more of a vacuum suck to it once the idle was rough than it did when it was not rough. Not sure how much is normal?

What I did find out is that after a while, I left it in drive, removed the oil filler cap, and all of sudden my RPMs dropped, it started shaking even more to point where it wanted to stall. As soon as I put the cap back on, it was still a rough idle, but not as bad and my rpms went back up. Also, it idles even rougher in the following order from most to least: reverse - drive - park/neutral.

Any more ideas?? I would greatly appreciate them! Thanks again for your help!

[culthero]

Sorry for the bump....any ideas weasel56 or anyone else?

[culthero]

check and cleaned idle ctrl vavle, still getting a rough idle. sprayed and inspected hoses, nothing I can see.

Should spark plugs be my next thing? Is it possible that with bad plugs, it would start up fine, then once it gets warmed up they would start to cause the misfire?

[Weasel]

Anything is possible... Especially if you haven't changed them yet at 107k.

Also, since you apparently have a code reader... you can take the misfiring cylinders, switch the coil with a known good one (cyl. without misfire code stored) and the spark plug to another.... clear faults, drive it till they come back. See which one the misfire follows. If it stays put, swap the injector with another and try again. That's just one way to figure out what component is giving you the trouble.

But just changing the spark plugs is a safe place to start, simply because you're due for them at 100k anyways... and the whole spraying the hoses trick to find vacuum leaks works great with substantial vacuum leaks, but not with the smaller ones. The computer compensates for it really quick. If your code reader has "data flow" you can read the upstream O2 sensor voltages. At idle at operating temperature they should switch in the range between 0.2 and 0.8 volts about every second. spray it all down with the cleaner while reading this, when you hit the tiny little leak, the voltages will stick at 0.8 volts for a few seconds. That's how I gotta track them down sometimes...