Cant find pid tune for quadcopter

I cant find a fine tune for my quadcopter...
My proppelers are balanced(there is a big differences between balance and unbalanced), I balanced the frame weight and i still cant make the quadcopter to stabilize.
When i have low P- quadcopter dont response to the transmitter and fall to the side.

Bit higher P- low reactions to the transmitter.

Bit higher P- oscillate from side to side and the reactions to the transmitter are still low.

This make no sense that the quadcopter is oscillating and there is no sharp reactions( wich mean that the P is too high), the reactions are slow.

My best tune makes the quadcopter stabillize for a minute and then oscillate.
And if i changed the pitch the quadcopter oscillate again.

Please help me!!

Sounds like your sketch has a logic error. If you show your sketch we might be able to point out your error.

Try lowering the D term. You can get oscillations from both a P value that is too high or a D value that is too high.

The P term is your main gain. Say for pitch, for every degree you are from the commanded position (X) it will apply a correction equal to P*X. This is the gain of your controller. If it is too high you can get oscillatory unstable behavior.

The D term is your derivative gain. This helps decrease settling time. If you only have a P controller it will apply the correction factor and the copter should pitch up, but the copter has angular momentum so it will want to shoot through the set point unless a correcting toque is applied in the opposite direction. The D controller sees this motion and tries to make is zero helping to stabilize the copter more quickly. This can go awry if there is a phase delay (which there will always be to some degree) It can make the motors kick one way to stop a motion which only causes a bigger motion in the other direction.

D oscillations will usually be smaller and faster than P oscillations, but a lot depends on the physics of the system. I would try tuning with just P to begin with, then add D to try to improve the performance, and finally add the I (Integrator) term if you are having issues with the copter not fully reaching a stable level hover.

search this list for PID
very recent discussion, lots of details

i think my problem is that the controller is too slow(14 hz - reading sensors,radio channels,send to motors).
the problem is with the radio channels, i am using pulseIn while i need to use interrupts and i cant understand why the interrupts doesnt work... i am using apm 2.6

Now we have the problem. For the filtering that needs to be done 14Hz is way too slow.

I am not an expert on APM, but you might try their forum to find some more experts in that area.