I have a cold start issue coupled with very very sluggish acceleration. I received a P0171 code several times.

2006 MCS with DDM CAI ~ 74000 miles

I first replaced the fuel filter because I didn't trust the last few tanks of gas I added to the MINI. For the first few days it ran perfect.
Then it started doing the same thing again.

I checked the fuel pressure and it is only reaching 30PSI and it is dropping back to 0 every time the key is turned off.

I am thinking regulator/damper at the injector rail but I wanted to see if anyone has any other ideas.

 

got the same code on mine this weekend, runs perfect other than giving me a hard start several times a week.

did you ever figure it out with yours?

also where did you check the fuel pressure from?