I've been struggling to diagnose an apparent rich condition on the driver's side (bank 2) to no avail. I've posted previously about my O2 sensor reading sluggish and high (rich) on the bank 2 front sensor. I re-logged looking at both banks, and both front and rear sensors. The bank 1 side O2's look perfect, switching back and forth rapidly. But both O2's on the bank 2 side (almost identical patterns) switch slowly and tend to want to stay at around .7 volts.

I have also logged short and long fuel trims - they look almost identical for both sides (although I have no idea what they SHOULD look like under good conditions - I am assuming that Bank 1 is good and therefore so is bank 2 since it looks the same). I have also logged injector pulse width for both banks, and both sides look identical too, following the engine rpm change very nicely.

Sooooo, I am wondering what would cause a rich condiiton reading in the O2's on bank 2 and not on bank 1, where fuel trim and pulse readings look ok?

I have replaced both upstream O2's with Bosch sensors, and I even repalced the bank 2 sensor with a known good original sensor and logged that too with the same results - shows sluggish and tendancy toward high readings.

I can post a graph of the latest logging if you think it might help to see the levels and patterns.

Thanks for your continued assistance.

PS - forgot - truck is an 03 Exp, 4.6l with 44k miles, AF1 intake and TP 93 performance tune!