fault codes p1242, p1109, and p0108 all came up this morning. Back story, did the timing chain on this car along with every gasket top to bottom, its a 2006 cooper S R53. Ever since i did this the car has been throwing the over boost code and eaten belts, fixed the belt issue with Alta hard mount manual tenesioner. In my effort to get rid of over boost code p1242 from my research it looked like it may be the bypass valve had failed, got a brand new one from mini, same code on the way home from dealer code came back, they said they saw the same code and blamed the map sensor. They wanted way to much for it so i got one from napa and got a maf sensor first, they really do look identical. And since i did that the car has ran like crap, I got the correct map sensor now but still bogs out to die undrivable, sometimes sounds like its on 3 cylinders. And i had to wait for obd scanner to get to me to see what the codes were this go round because i had no way to get it to the shop in town to pull them, and a vag com computer my fired has didn't see any of them. I was told by mod mini on youtube to try a crank position sensor, not a terrible idea but nothing i can see from these codes points at that to my untrained eye. Any help would be greatly appreciated!

 

and add in now p0300, multiple misfire code. just tired switching back to my original map sensor and it ran much better, almost derivable, reved up to 4k-ish and got all the Christmas tree of the dash to light up. I have pulled all the spark plugs and they were all wet with fuel, i don't have a boost leak around the boots of inter cooler, i am just lost!

 

My guess is you got the timing chain off just a hair and everything is going wonkey. It doesn't make sense that it worked before, you did gasket work and a chain and now you have multiple codes.

 

I've had luck simply cleaning the map sensor. Nothing aggressive. I use a dry q-tip. Definitely not brake cleaner! Mine occasionally get oily and then throws codes.

I'm not surprised the Napa sensor doesn't work. Some of their parts are OEM but some are not so good. You either have to do a lot of homework or are simply taking your chances. Go MINI or a known good quality aftermarket.

 

It sounds like you install the timing chain with the slack on the wrong side. All slack needs to be on the tensioner side. If you have slack on the drive side, when the engine is running the cam timing will be off. This will cause crazy codes.