Wobbling in loiter mode

Hello, I have a little question about the tuning of loiter mode. My quad flies very stable in stab mode but when in loiter mode it is wobbling. I don’t know exactly how to tune this. Please advise.
I have put a video on youtube of my loiter problem.

I’m using the apm 2.6 and arducopter 3.1.5

Hello voyager,

Have you tried to tune the Loiter performance?
Since Loiter incorporates the AltHold algorithm, you might need to verify the AltHold performance too.

Here you’ll find more information regarding the tuning and verifying the loiter performance with dataflash logs:
http://copter.ardupilot.com/wiki/loiter-mode/#Tuning (scroll down).

Hopefully this helps you out!