The Auto Tune kit monitors the fuel mixture (by installing the included Wide Band O2 sensor in the exhaust). It then sends this information to the Power Commander V and automatically corrects it while you ride. Each map that we offer has preset Air/Fuel ratio values included that we find to be the best overall settings. This lets you simply plug in the unit and let it do the work. For Harley Davidson models we ever monitor and adjust each cylinder individually for increased precision as on these models required fueling can vary significantly between the front and rear cylinder.