noise once i shift the gear to D or R

Hi,

I have Porsche Cayman s 2006 , there was a noise once i shift the gear to D or R , then it disappear once i accelerate , it happens to be the torque converter , i have changed it and the noise is gone , then the check engine light went on , on the diagnose computer it mentions (transmission control unit ) which wasn't before there and it doesn't shift properly :( , appreciate your input on this matter

regards