Engine suddenly running very rough
 

My E53 3.0 was running just fine yesterday. Started it up this morning and it was running very rough. It seems to be shaking. Drove it around the block and it seems as if power is not all there, almost as if it's not running on all cylinders. Parked it.

Anyone have an idea what's wrong? What could go wrong from one day to the next?

Thanks.

did it trigger a check engine light? Vacuum leaks come to mind as well as a bad coil. both would throw a light thogh.

Yes a check engine light came on. Yesterday no light and it was running smoothly. Only thing that's different today is that it's a cool this morning (I got on the road super early).

My thought would be you have a vacuum leak on the intake elbow, and that it is starting to crack just enough to be outside the parameters for throw a lean code. I would buy a code reader so you can get a code for when it happens again. I just went through something similar 2003 3.0.

Thanks for your reply. I just recently had the air intake boot to the Throttle body replaced. I'll bring it back to the mechanic.

Engine suddenly running very rough
 

Certain codes will trigger limp home mode. Pull the code and reset via obd (have Mechanic do if you don't have obd reader yet). It will feel like a couple spark plugs wires are disconnected when in limp mode. Happened to me once right after a fuel fill up I thought I bought polluted

When my DISA valve died I had very similar experience. The difference being it ran ok at speed just idled like hell

I've had this happen to our X5 multiple times. Usually when it's been sitting a couple days or more.

I would get a misfire code for 2 or 4 cylinders. I pull the plugs, clean and replace... that would usually fix the issue for awhile. Tried switching the coils around to see if it would follow the problem, but it didn't.

I've changed plugs with new and that will make the problem go away for awhile. Cleaning the mass airflow sensor didn't seem to do anything.

Had an aftermarket AFE air cleaner (oiled type) for years and since replaced it with an OEM a few months ago. Problem hasn't come back since then.

If you don't have a fault code reader... you might consider it. This has helped me save a lot of time/money troubleshooting issues and resetting fault codes:
https://www.bavauto.com/sr-300-16

Bad coil.
Just happened to me.
Failing coil, finally threw a code.
Ran rough, stumbled, shaking etc.

Could be a bad coil pack which you can get lucky and identify at times just by checking the codes. Anytime it throws an error light get the codes read.

Another possible cause is the mass airflow meter. My 323i would do the random rough idle when cranked in the morning at times. Did this for a few years actually and eventually I got a code. Replaced the MAF and no more issues. When it did the rough idle I could shut the car off wait a second and crank back up and it would be fine for the rest of the day.

Issue resolved! It was 2 bad coils. Mechanic changed them in about 20 minutes. I have my E53 back! Thanks for all the help.