Where do I start. I've got 40 hours wrenching and at least that many doing research. Bought my daughter a 2007 mini cooper r56 90k with a misfire and got a good deal. I thought I would figure this out for a couple hundred bucks. That was naïve. The code was a p0301 an p0300. Upon closer inspection I noticed a new vacuum pump and walnut husks dust in some confined areas so it became apparent that some one else had been chasing this misfire got feed up and traded it in. This is my story in chronological order:
Replaced gas cap
Checked vacuum system in engine bay
Changed plugs
Swapped coils still #1
Swapped injectors still #1
Changed fuel filter
Ran bore scope to make sure intake valves still clean. all good
Cleaned and reinstalled vanos solenoids and cam sensors
Pulled exhaust manifold and huge chunks of carbon fell out of 1 and 4. 2&3 looked much better for obvious reasons.
Pulled head thought had burnt exhaust valve. tons of carbon and bad guides but no damage.
Reinstalled cams and head
New Eccentric shaft sensor
Runs great but starts misfiring at 90c, same as before.
Unplugged exhaust vanos and idles perfectly.


The obvious is a bad vanos solenoid but I'm not 100% convinced. Anyone have experience with this?

 

You can clean or replace the solenoid quite easily if needed. My suggestion is if you have determined you need a VANOS solenoid by cleaning, they are fairly inexpensive, and you're always better off replacing a degrading part. We have them here if needed. We also have a DIY that goes over the replacement with a lot of information if needed.

 

I cleaned the solenoids as one of the first things I did early in this saga. I checked them again and they still look good. Clean and the shuttle moved back and forth smoothly. Both checked out @ E: 8.2 ohms In: 8.6 ohms. How do I check to see if the solenoid are good? I'm not getting a code other than p0301. My concern is that this is a different upstream problem. I have read that replacing solenoids often do not fix the problem.

 

I replaced the eccentric shaft sensor as well.