W126 new voltage regulator = adjust lambda?
 

Put a brand new regulator in. A Bosch unit. After doing so my voltage at battery is reading 14.15 v constant. Before I was hovering just over 13.

Oddly the engine was running rich. I had just adjusted lambda a week prior. Now I had to do it again and I had to very much lean it out.

Coincidence or expected behavior?

Lambda reading takes into account voltage, so if your new regulator is making more contact and putting out more juice....that would def. change the mixture.