I've found that occassionally, LFS will fail to recognize the left-right limits of the wheel, and will react to any small motion of the wheel as if you were cranking it left or right. If you think this is happening, just turn the wheel all the way to the left, and then all the way to the right, hitting the stop on either side. By doing this, you are effectively calibrating the wheel within LFS, and it will respond appropriately.
Another problem you could be having is if the DFP is still on 200* mode. If only one of the green lights is illuminated on the DFP, that's the problem. Hold "Select" and "R3," then press the right-hand shift-paddle to force the DFP into 900* mode. Then, make sure the "Wheel Turn" option in LFS is set to 900*.