What should 02 readings be at W.O.T. ?

[turbotaone]

I just got a scanmaster 2.1 and I'm trying to figure it out.
I know that the 02 readings should be around 770 right ?
Well mine jump all over the place at idle from 0 to 860.
What should they be doing at W.O.T. ?, It looked like they
were dropping to me. They went from the 800's down to
the 400's. Is this normal ?

Thanks James

 

[turbofrank]

Top of 3rd gear at wot many say .780 i stay from .720-.750 never
any lower than .720 before i worry.