I have a 2009 Mini Cooper S 87k miles on it that is running rich. We bought a Mini Cooper that needed a little work to get it going. The car had a check engine light for the O2 sensors.
The first thing I did was the timing chain, exhaust gear, timing chain guides, and gaskets. In addition I did the oil pan gasket and cleaned up all the broken timing guides out of the pan. Valve cover and the gasket was also done. I took care of the mini’s oil leak and replaced the turbo oil lines and filter housing gaskets. New O2 sensors went in up and down stream. Vanos solenoid, cam shaft sensor, map sensor. All the adaptations were reset.
I could see that the previous owner was in there and I corrected several broken parts. The valves were cleaned. He stated he put a new high pressure fuel pump in.
The car is running at -25 fuel trim short term. It would go from close to open loop and do a little stumble. The mini has plenty of fuel pressure and it actually seems high to me at about 900 psi at idle. I replaced the fuel injectors but it made no difference. I also disconnected the tank vent return, but it had no effect on the fuel trims. I’m puzzled at this point. I have checked a lot of things and they appeared to be within specs. Anyone have any ideas?

 

got the same problem, no cel or anything but running -12.5% to - -15% long term fuel trim. rock solid idle, nice boost, clean filters and anything, valves are clean, timing set is brand new. i cannot find what is the problem really.

 

I have the exact same problem. No check engine light or codes. Short term fuel trim is -25 long term 0 while idling, yet the car runs perfectly cold and hot. In the middle temps as the car is warmng up it will stumble like it is too lean for a couple minutes, then it is fine. During regular driving the short term is between 0 and -19ish, long term 0. I bought the car with a rebuilt engine and same as you, it had a recently installed high pressure fuel pump. All new 02, valve cover, thermostat, water pump, injectors, coils packs, plugs, you name it. Timing chain new and checked. Same as you, I have 925 to 1000 psi at idle and elsewhere here on this site it says the computer sets this at 725 psi at idle.

My first thought is the new pump may be aftermarket and does not communicate with the ECU to drop the psi, resulting in too high pressure.

Did you ever solve this?

 

I have an 07 R56 with 141k. Same problem, CE light is on and I can't pass the smog test to register it. Lots of new parts:
new o2's
new HP fuel pump
new valve cover
new MAF
new VT solenoid in the rear
new air filter
plugs - NGK IR
cleaned cam sensor
no other codes, just P2188
runs well, good power
fresh oil

I have Bimmerlink, not sure what tools on there can help pin point the problem.

thanks!