I have just loaded 3.83, and I can't get stable tach anymore, nothing has changed on the hardware it must be a default setting in 3.83 vs 3.76.
The only thing I have noticed is the drill speed is showing as 383-0-383-0-383 rpms in TunerStudio, because it keeps dropping zero now.
I have checked my settings and they are the same as 3.7, which I was using previously.
The interesting thing is the drill is doing nearer 400 rpm and the revs aren't doubled like 3.76, so maybe there is something in what you are observing, although mine isn't a true test because I haven't got stable tach/sync etc
I look at it again tomorrow and try and solve my tach errors...
Mike
PS Perhaps you could load 3.76 and see if there are changes.
UPDATE Changing Ignition Input Capture to Falling Edge from Rising Edge has cured the sync error, as can hand wind and get 65 rpms showing consistently with no zeros now!
I checked my 3.76 settings, and they gave stable tach with no resets using Rising Edge, but 3.83 needs Falling Edge with the same hardware...
