I hate to keep this thread alive, but I made another discovery today that is pertinent to the idle BLM splits that were chronically showing the right bank lean and the left bank rich.

So some background - it's been rainy and cold all week and all I've been able to do is work with startup fueling and idle trims. I've been noticing the wideband maxing out lean periodically when both left and right integrators synched up for a lean swing. I've also been noticing an intermittent miss at part throttle that also seemed to briefly peg the wideband lean (presumably from raw fuel getting in the exhaust). I began to wonder if my individual trims are too extreme and are causing these problems. Today I had a bit of time to experiment with trims in open loop while trying to keep my wideband matching commanded AFR. Oddly, the individual trims seemed to make very little difference when I added or removed from one bank. But while I was doing that I noticed that when I forced AFR above 14.5:1, after a few minutes the right side O2 would start trending down around 150mv and then eventually flatline at 40-50 (this is with BLMs reset to 128).

Then, as I was looking over kur4o's nice new controller window it occurred to me I've never tried moving EOIT. Sure enough, when I got to 129* things smoothed out somewhat. I then switched it to closed loop and to my amazement there was only a 2 point split. Toggling the EOIT override while in closed loop I witnessed the BLM splits come back and then go in unison with the override. So I suppose my lean condition on the right wasn't an exhaust leak or so much an actual lean condition as it is raw fuel getting into the exhaust during overlap. So I guess I'm going to try using 129* EOIT and start all over with individual trims and see what happens. I expect my off-idle fueling will get way out of whack due to loss of wall film.