To use the auto tune feature: place the loco on a long straight section of track, 5 or 6 feet long if you have it. Then using your controller set CV54 to 0 then press F1. The loco will tear off at top speed and gradually slow to a stop. This calibrates the decoder to the motor and it should run better after this. Bear in mind you may have to do it several times for the best results and make sure the loco has been running for a good while before doing it.