My 05 S cabrio did weird things this morning. While driving to an appointment the service engine light and the "EML" light went on and I couldn't go over 25 mph(limp mode) . When I turned off the engine it shuddered to a stop. After the meeting it stared fine...but did not have positive boost on the supercharger, I could go down the road at 45- 50 mph but didn't have any real boost (or acceleration) when I pressed on the gas. Any ideas?
Thanks

 

The bypass valve might be stuck or broken.

 

x2 on the bypass valve

 

i had the same problem... but when i turn off the car and restart it, the problem goes away.. and sometimes it will come back again. i thought that was my poor unichip tune. i should try to unplug the unchip and run on stock ecu see if problem still exist.

 

My '05 MCS does the exact same thing. I have been reading on here and this problem seems now to be an epidemic! Starting to look like some sort of design flaw with darn near all MINI's we should get the dealers to get these little 's fixed for free!

 

Yep, it was the bypass valve...it "biffed". Another problem that came up was a clunking sound as I started to let the clutch out and at every shift up to third....what the..? The dealer had replaced the passenger motor mount about 4-5 months ago and the bolt holding the engine bracket to the mount came loose. I couldn't find anything for about 2 weeks and then a mechanic buddy of mine looked at the passenger side as I let out the clutch and he couldn't see anything either, then we opened the hood to look around and just by luck I started the car again, let out the clutch and he saw the engine bracket move about 4"...me thinks that wasn't the only loose nut on the car, the other being the mechanic at the dealership 1 1/2 hrs away.

 

So, it looks as though I too am in need of a new BPV

 

zip tie the valve open and see if the problem goes away. if so then you will def know its the bypass valve.

 

Will do!