Heres one to get you all guessing, got me stumped!
Car drives well, however occasionally there is a "thump" when the tranny goes from 5th to 6th. not always.
Also the tranny seems to "hang" back a little when put into reverse.
Here is the good bit.
Blew a HID low beam LHS (aussie passenger side) removed air box, intake hose to S/charger, and disconnected several cables associated with air box.
Fitted globe replace air box etc, lights OK.
Now the transmission does NOT "thump into 6th, and reverse "seems" OK
Any ideas?

 

LOL! Eh mate. Did you disconnect the battery prior to HID lamp swap? If yes, then a hard re-set of the ECU was performed too, carrying away resolved faults. Yas from down under drink warm or cold Fosters?

 

My guess is that the various connectors with the airbox that you unplugged and obviously replugged had something to do with it.

Most of these "gremlin" type issues are nearly always traced to a connector issue.

Of course if the battery was disconnected, as said, then the hard reset has sorted the gremlin, and it may well stay that way, but if the fault that caused the issue is still there it will return eventually.

 

Thanks for the show of interest gang, for the record the battery, nor the bumper were disconnected or removed.The only connectors disconnected were the light harness and the airbox harness!
Wierd

 

My car would randomly do the hump going into 6th. I haven't noticed it in the last few months. Think it could have also been cured with the reset.