The rear 02 are 4 wire and only provide sample readings for possible CAT clogging. They have nothing to do with AFR targets.
I've seen (forget where?) that we can run only the front O2 sensors w/a set of headers? Does it require a different flash? Is there a reason/benefit?
Ignoring the "US flat spot" for the moment. If when, in closed loop mode, the ECU is correcting based on the front O2 sensors input along with other variables. What is the "tune" doing?
In post #12 you mention that you disable the O2 sensors? Is that part of the current K67 tune?
We put RCK3/HP power kit enables in the ECU and all the magic starts for running in open loop mode 100% because we turn off the O2 senors. Now only limited information like engine coolant temp, inlet air temp, knock denotation are the basic inputs for the open loop mode.
Benny, is this you? https://youtu.be/Yl5Pn_ze0ww Did it need anything else besides the exhaust? Mapping etc? Sounds amazing!! Sent from my iPhone using Tapatalk
www.s1000rrforum.com
Here another tuner states they are running in "closed loop" mode and the ECU is correcting, like you have mentioned in the past.
EDIT: Found this. I've read posts where people mention open and closed loop but I never educated myself on what it is and why I should care. For those that also don't know, I found this article and old video. Now I finally understand why the car will sometimes stumble when pulling out from a light.