I noticed in a recent scan that in the middle of an extended idling period, the commanded afr suddenly went lean (15.75) and o2's pegged low for 7 seconds, then went rich (13.98) and o2's went high (but not max high) for 6 seconds, then went back to normal (14.63). Could this be for an emissions test or some kind of test that gets run when the OS is "idle"? I can't find anywhere in the tune that would set the EQ ratio to less than 1.0, for any reason. This is closed loop, idle settings are all stock, and the actual idle speed didn't change much during this whatever it was.