i was just giving the engine bay the once over and found this wire not connected to anything, and no apparent place to plug it in (though I did fish too hard, it was cold out). It's by the firewall drivers side. It's the middle bundle of wires there. Any idea?

 

I think it went to the flapper in the air intake housing since your car is a JCW.

 

Correct, it's the connector to open the auxilary air intake flap on the factory JCW cars......it opens at or above 4500 RPM

My R52 has the same connector, and I am missing the factory air cleaner box

Bryan

 

Yes, it is for the factory JCW CAI.