5 speed auto torque converter lock up

[bsell]

I have a 09/94 build 525I with the 5 speed auto installed. When running WOT climbing up fourth gear, I get a sensation where the engine speed stops climbing but the car keeps accelerating (almost like a slipping clutch in a manual trans car finally grabbing) then the engine speed continues to climb with road speed. Does the torque converter lock up above a certain rpm under WOT conditons? Is there a matrix of the conditions where the converter locks up?

Thanks,

Brian

P.S. Winter driving on the autobahn is hell on the front-end paint!:(