'91 420 SEL. Was performing the landiss.com/mixture trouble tree test and only got as far as the static test (engine off, switch on) for duty cycle.
At the X11 plug (pin 2 &3) mine reads 30% @ +3.4 Volts. I was expecting to see the 49 state 70%.
Nothing in the rest of the document says what to do if it isn't 70% at the git-go.
With the engine running it jumped around between 64-75% and within 10% at 2500 rpm. Which according to Landiss is what it should be and the O2 sensor is working.
Just curious about only seeing 30% static. Don't know what that is indicative of. Of course reversing the leads I get 70% @ -3.4V.

TIA, Dave