I was so impressed with this easy fix after being told by a handful of people IRL that the issue was this sensor, that sensor, timing, etc etc. had 16 error codes all over the place.

There are posts all over about the DISA defect that causes all sorts of issues and could very easily blow your motor but I'm going to post this anyway because not one post I saw was simple enough for my old brain.

Symptoms: Wont idle or barely does, rattles or whines with a noise like a hard plastic blocks hitting each other (at idle). What you might think is a timing or a few clogged fuel injectors. Mine would die coming up to lights or worse, when taking turn's with no throttle (losing power steering).

Test:
1.Easy, listen to a box 3x6 box bolted to the drivers side of the engine (DISA module) as it idles an have someone turn it off. Its a mechanical air valve. If it rattles uneven, like there's broken plastic in there, well, its broken plastic in there.
2.Easier, if u have an ODB tester, reset all the codes, shut off, start, idle 20 seconds and reread. If you get misfires on all 6 cylinders and lean on both banks in that short of time, there's a very high probability the DISA valve is broken and the engines getting way too much air. in in that 20 seconds you will get 11-16 error codes. The ones that matter are the misfires across the board and lean. The others are symptoms.
3.Does you inline 6 from BMW have 80k+ on it? rebuild the DISA, its a defect and dont dont risk the car for a $70 part that takes 20 minutes to fix.

FIX:
You can buy a entire 3rd party plastic unit from $120-400. Read over and over how the plastic ones rebreak after xx miles so buyer beware on those.

I am amazed with this aluminum rebuild kit which actually prompted me to write this post. Its so much better then even OEM new cause it will not break again, ever. It seems really high quality too. http://www.ebay.com/itm/151667841418 . The add seems a little cheesy like joebob is machining this on the side at work but i have to tell you. When you get it, you will see why the kit costs $70. Way worth 2x more then the plastic rebuild kits the forums complain about. The instructions look harder then it is to install too. it took me literally 5 minutes. It took longer trying to read the instructions.

Look at any youtube video how to take it off. Its 2 torc # 40 screws and pop the air filter cover off (super quick and easy). One thing to take very seriously. A broken DISA probably has a metal pin hanging off the end inside the engine compartment. Watch the video's carefully. You DO NOT want to drop that pin in the engine taking it out. Mine fell out right inside the hole going in, i was able to grab it with a magnetic screwdriver. If it goes back in and drops down into the engine, DONT start the engine. It needs to be fished out with magnets or the head needs to come off. If you can, hold the broken plastic valve in place as you pull it out. It basically holds the pin in but will fall out if not supported.

Oh one last thing. those guys i got it from on ebay. I ordered Saturday night at like 8-9 pm and it showed up on Monday even though shipping said a week. I'm not affiliated, not a mechanic, never met them. I'm just very impressed with the kit and how fast i got it.

Good luck and feel free to ask anything.
Tim.