@chris4 said in Piezo, Varning G28 readings not consistent:
M558 P8 I1 R0.4 F420
You can try adding some parameters to increase the accuracy.
M558 P8 I1 R0.4 F420 T6000 A10 S0.01
This will cause it to probe at least twice and will reprobe up to 10 times until 2 consecutive probe results are within 0.01mm
As for tuning the piezo sensor itself, try searching the forum for some tips on what others have used.