I think I've figured out the root cause. My ground wire for the sensor is sent to ground and not the ECM. Apparently the E39 has a pull up circuit on the O2 ground wire that is 0.9-1.1v (reference: https://forum.hptuners.com/showthrea...p-harness-Help)! That explains why I'm having to provide +1v to get a reading on the ECM. I have a new pigtail for the O2 sensor on the way that will go to the ECM and should solve this closed loop issue.
With that out of the way I will indeed need to get a wideband. I see that innovative has a wide band setup that has a tunable analog output. Could I not send this output into the ECM signal and log the voltage? If I set the output to provide the same voltage at stoichiometric AFR that the normal O2 is providing then couldn't I just use the wideband for everything?
I realize that it's a little ridiculous to work this long to find the root cause for the O2 sensor not working just to turn around and try to replace it with a wide-band, but I really wanted to make sure everything was working properly before going to the next step.
This leads me to the next question: what is the conversion from O2 voltage to lambda? I must be blind because I can't find any AFR, equivalence ratio, or lambda function to log (other than equivalence ratio command). I also can't find a VE or target lambda table to adjust. What am I missing?
Daniel