Is there a way to check the duty cycle using voltage readings?? I read this article BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT and followed the formula:
reading from pin 2 & 3 on x11 connector divided by battery voltage and then 1-the sum of that and convert it to a percentage. So this is what I got:

my reading from x11 was jumping between 6.5v - 5.Xv
my battery voltage at idle was 14.4v
I divided 6.5/14.4 = .451
then I subtracted 1 - .451 = .549 which gives me roughly 55% + or -

Is this correct? Can anyone tell me what the normal duty cycle for my car should be roughly?
1990 190E 2.6 California versioin
It idles around 700-750 rpm which is what it says on my yellow sticker on the radiator bracket.

__________________

1990 190E 3.0L