quadcoptor Tuning

Hello world i am Tarkesh ,i am building an arduino quadcoptor for my personal project ,my project is about to be complete , but i am stuck with some tuning problems ,my quad will be communicatong via xbee,so all the PId tuning is done through serial communication in my code attached .

So i tried stabilizing rate mode and got the following constants value
This seems to work ,but not that fine ,it hold the angle for sometime like about 10seconds ,and during that period i see little vibrations ,so when i lower the I gain ,my quadcoptor tends to lose the upthrust and drift along Gravity ,so i thought i might increase my PIDoutput limits from (-250,250) to (-300,300),but with this new limits my quad doesnt even hold any angle

Is something wrong with my code ,or.am i missing something? ? guys do give ur views thanks in advance :slight_smile:

pitch_and_roll.ino (7.92 KB)