190E fuel/oxygen mixture without lambda on/off ratio

[joan1094]

Hi all!.
I own a 1986 190E, manual transmission, engine 102 962 101.
I've been having a problem long time ago. My benz does not have lambda oxygen sensor nor pin 3 in the x11 diagnotic socket thus i can't measure the lambda ration with duty cycle and now it is consuming a lot of fuel and hesitate when I accelerate .

I wonder if there is any way to calibrate the mixture, similar as the 50% with duty cycle?

Thank you all! and sorry for my english