Dreaded p1273 and p1283

[Stealth Fxxss]

Hello 05 fx35 awd. Got the p1273 ok can find vac leaks,redid the plenum gasket ,throttle body,valve covers, took out vatch cans,changed all o2 and AFR
Changed fuel damper. At first it was only p1273 b1s1 lean. So i switched AFR sensors from side to other. I did that an started getting p1283 b2s1 lean.so i figured sensor bad . Got a new one installed did the peddal relearn,throttle,euc,an stored.valuse relearn . Still have p1283 .any advice?

[VStar650CL]

If you didn't do the P0102 trick to clear all the relearn values, I noted in your other thread how to do it. If you already did, scan the sensor voltages and see if the baseline value on your new sensor is off. The sensors are 1.5V types and not the later 2.1V jobs, so aftermarket can be a crapshoot. A/F's are very different and very precise compared to traditional HO2S's, so even a small shift in baseline voltage will cause a rich/lean condition and resultant codes. Since it's only one bank, the other likely culprit would be a small exhaust leak anyplace in or around the cat inlet or a dirty/sticky injector on one or more cylinders. Pinhole or bolt leaks are most easily found by having an assistant block the tailpipe with a shop rag to create backpressure, you'll instantly get a ticking noise from any tiny leaks.