So since I've purchased this car (2007 Mini Cooper S) about a week ago, I have not been impressed on the performance. Not having owned this car since day 1, I don't know how its suppose to drive. Anyways I bought that Diverter Valve Adapter on amazon, and when I was installing it I noticed the wiring harness to the Diverter Valve was just hanging there. After taking the car for a test drive after hooking everything back up the car has almost instant response, and accelerates like a completely different car. Would having this harness unplugged cause the car to lose power? Also it wasn't throwing any check engine lights when it was unplugged is that normal?

Also after the test drive I can smell some oil burning off.... thoughts??

 

This is from a write-up about diagnosing our engines:

Diverter Valve. If the turbo is producing boost, and you take your foot off of the accelerator pedal, there will still be some boost in the intake system. When you take your foot off of the accelerator pedal, the throttle plate closes; so the excess boost has nowhere to go other than back to the turbo. If, at this point, the pressurized air cannot be redirected before it reaches the turbo, it can eventually destroy the turbo.