[Ed Wright]

Jimmy, I would set the min RPM for closed loop above your 2 step RPM. The misfiring on the 2 step gives a false lean indication, at least on mine. A misfire, incomplete combustion, puts more oxygen out the exhaust than a complete burn. Higher oxygen to an O2 sensor = lean mixture to the ECU. Closed loop during a misfire in closed loop means more fuel added. Since your O2 is in a primary tube, it may not show as lean then.

If your engine has been dynoed with 8 wide bands, and they knew all 8 cylinders had the same air/fuel ratio (mine did not) putting in in a primary tube would be better than the collector.

Mine had a 9% spread between cylinders on Patterson's dyno, with 8 wide bands. I run mine in Sequential mode so I could make them all the same. We tried to pull mine down to 3000 to get them all the air/fuel right in the 2 step RPM range. Would not pull down that low. Seems like 5000 is as low as we actually pulled it.

Yours being in one primary, it may not see as big a false lean indication as mine does. Mine looks like ~15-1 on the 2 step. Also looks very lean in the bottom of each gear. We pulled it past that RPM (~6200) so I know it is actually correct there. In closed loop mine adds fuel there, and slows my car down. If I were to try closed loop again, I think I would set my minimum closed loop RPM to 6500.
Edit: had a brain fart. Forgot about FAST's ten second delay. Setting my min RPM to 6500, the run would be (or close to) over before it went into closed loop.
You should talk to David Page about this. LOL