GPS problem

I have problem with GPS it won’t hold position in any mode (Loiter, AUTO), but it work ok with ALTHOLD.
What did I set up wrong? Or what I have to tune to make it work?

Log is attached below.

[color=#FF0000][b]Moved to 3.01, changed title.

First of all, “need Help!” is by no means a suitable topic title! A topic title should reflect the problem.
Secondly, You should post in the appropriate subforum - that increases your chances to get help!
So far for the admin stuff…[/b][/color]

GPS does not work in alt hold because alt hold does not use GPS. Alt hold only uses the barometer.
“Won’t hold position” is also not very precise. Please explain in detail, what the copter is doing or not doing. Is it moving around? If so, how much? In which direction? Does it move in circles? Etc.
The more precise your error description is, the better is your chance to get a good reply!

I start up copter, let it spin for a few seconds, then i take it up in STABILIZE mode, everything fine by that time,
But when I switch to LOITER mode copter freeze for 1-2 second then start moving to side most of the time to left of heading direction, after it flies about 10FT of that spot when i turn loiter on, i switch back to stabilize.
If I switch to auto mode copter will fly any direction he want ho fly, but not the way it should go.

I also have a similar problem. since I installed the update firmware 3.01
The drone does not keep point loiter mode.
When I program a waypoint flight by the drone in every sense …
:question: :question: :question: :question:

Any clue how to fix it? … clination/

You’re experiencing what usually is called “toiled bowl effect”. This new firmware, and most lickely every firmware in the future is/will be highly sensitive to Magnetic Interference. In a multicopter there are power wires coming from the battery and going to the motors, through which passes a lot of electric current, a magnetic anomalie is created, and interferes with the compass. You’ll probably going to need an external compass mounted on a 10cm mast, it solved all my problems. Read the link posted by StefanG, and watch the videos from Randy Mackay on youtube. Things you’ll need to do to have a perfect loiter and auto, set declination, compass calibration, and compassmot. There’s a lot of info on diydrones.

I moved APM board up on top side(it was on bottom side) and extend GPS module above APM on 2".
After compassmot test I got value 87-95%(it was above 250%).
Quad now much more stable, I could hold it on one spot within 4’ circle.
I will investigate furthermore.
Thank you for reply StefanG.