Im stuck trying to get cruise pitch to stop oscillating. Ive read the tecs wiki a few times. Im just stuck and could use some help. My pids are tuned plane is leveled and flys great in fbwa and manual. Just cruise and fbwb i get a -4 to +4 degree pitch occilstion. Like once every second.
The assumption that your plane flys great in fbwa may be mistaken.
I experienced something similar with a mild ~1Hz Pitch Oscillation and the solution was to cut PTCH_RATE_I in half.
I found out that the behavior of Autotune, to set PTCH_RATE_FF and then blindly copy the value to PTCH_RATE_I can cause oscillations due to critical PTCH_RATE_I values.
Set PTCH_RATE_I to the default value of 0.15, fly and check if the oscillations are gone.
If still there switch to FBWA directly and see if the oscillation stops.
That would be the point to look into the TECS values.