Since you have replaced the sensors, it sure sounds like an issue with cam timing. 

Were there any usually noises indicating a 'stretched' timing chain?  Could it be possible the timing chain may have skipped a tooth?  Was there any 'sludge' under the valve covers?

Do you know if you have proper weight oil in the engine (5w-30)?  Sometimes, using the wrong weight oil can cause havoc with cam timing...

Ken

P0014 isn't a problem but oh my god, P0015 is a death sentence.  I would take it to the nearest dealer and trade in on anything they would trade with you.  The last time I saw one throw a P0015 code, every bearing in the engine went TU.  Not a pretty sight.  I think it may have even been a 2008 as well.  No sir, this is not good at all.  The next high rev may just be the one that spins your bearings.  SELL, SELL, SELL!

My first post here. Love Mini's! They rip! Fun cars to drive!

Having issue with my Cooper. 2008 N12 engine.

After you start it the engine seems to run in a high idle mode for a moment to warm the engine. It seems that the moment it drops out of that high idle it doesn't like what it sees and it throws the code P0015 or P0014.

Pulled off valve cover and checked timing chain tension, guides, the timing, and every thing seems to check out ok. Both vanos solenoids are good, as well as their wiring to the ECU. It looks like the timing chain and Exhaust cam adjustment unit have been changed. The chain tensioner is also the updated version with the dimple in it.

I also checked pressure to depress the tensioner and it took a 35lb dumbell to depress it.

Anyone have any ideas as to why the computer is sensing advanced or retarded timing on my exhaust cam? Car has 100k miles on it.

I'm lost on this one.

Oh cam sensors are both good also, as well as their wiring to ECU.