AFR difference between the banks

Jordo!

I don't think it's ever in open loop. The target maps cover all load ranges, and that means there is always a STFT and LTFT. It's just that beyond a certain load range, you can set the targets to whatever you want without the ECU trying to wrestle the engine to run close to stoich (assuming it does that -- I seem to recall uprev commenting on this, but no idea if its accurate).

The cylinder trims vary most likely due to flow variation -- massive correction implies either the sensors are off more than one would like or your set-up is just flowing unevenly, which to some extent is unavoidable.

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