I designed small circuit which "steals" signal from lambda sensor and shows if engine runs on lean, stoichiometric or rich mixture. I documented circuit, and PCB project, and soon I will write about two of these circuits which are already mounted in cars.
I would like to hear your opinion about this circuit, I posted a note about it here
Notatki: Lambda sensor based Air-fuel ratio indicator [AFR] 1 hope you will enjoy reading. I also hope I didn't make to much spelling mistakes - I am not native english speaker.