I have a 2010 Clubman S with 99,800 mi. I have just replaced the timing chain, thermostat housing, de carbon valves, and changed tranny fluid. Since then I have hard starting issues. I have to hold the throttle open to keep the engine at between 2000 and 3000 rpm until it warms up. The performance seems off like the turbo is not giving any boost. There is an intermittent stumble under acceleration. I have gotten the following codes on my Scan Gauge- P115D, P2187, P2178, P1487, P0001, U3FFF, and U3F00. The Bentley Manual talks about Mass Air Flow A Too High, Fuel Trim Limit Exceeded Too Rich, System Too Lean at Idle (Bank 1). The "U3" codes are not listed in the book. I have double checked all the electrical connections. Anyone have any ideas.

 

Moving this to the Gen2 area for you. The Gen1 engine is different.

 

After it warms up it runs okay?

 

It runs better but not great. It will still have the occasional stumble usually under acceleration. It used to accelerate briskly from 75 to 100. Now it slow to get from 75 to 85 or 90.

 

OK, can you give more history to this? Why did you change the chain? had it snapped? Did the rail or guide disintegrate or was this purely prophylactic maintenance? If it did snap have you replaced the valves?
It is possible to reassemble during chain replacement and get the timing out, did you double check x2 with the camshaft tool that everything was in place at TDC?
I have no idea about the codes.

 

Chain was making noise so it had stretched. It did have minor guide damage. I double checked with cam tool for TDC. It seemed to run OK after that, but then I decided to do the decarbon valves and the thermostat housing was leaking. Since it was close to 100K miles I drained tranny fluid and put in fresh. Since then it has been hard to start and idle until it gets a little warmth in engine and performance remains sluggish.

 

Sounds like a massive vacuum leak. If you have a N14 replace the PCV hose between manifold and crankcase. If N18?