How quick we forget ...
viewtopic.php?f=1&t=19460&p=231326&hilit=Motorcycle+Consumer+News#p231326BTW - they totally dorked on the interpretation of "Open Loop" v. "Closed Loop". "Open loop" is a non-feedback scenario. Removing the 02 sensor (or turning it off), put ANY ECM into an open loop state; in the case of the SD, mapping no longer adjust to achieve an "ideal" (KTM's version of ideal anyway ...) air-fuel (A/F) ratio.
"Closed loop" operation would be in using the O2 sensors. That is, the O2 sensors close the feedback loop; where the EFI relies on not only the input parameters of air temperature (and some systems, humidity), air pressure, engine speed, throttle position, in some instances gear selected, bike speed, engine temperature, etc. These sensors as most of you know, measure the oxygen content in the exhaust stream, and fueling is modified (algorithmically or by map selection) dynamically to achieve an optimum (again, an optimum according to a given manufacturer, and regional emission control requirements ...). Without O2 sensors, there is no "feedback" whatsoever, and as a system, the EFI is effectively operated "open loop", with the arguable exception of the riders right hand being involved.
EDIT: Another thing they dorked on, is that an EFI will try to push the fueling to the "ideal" stoichiometric A/F of 14.7:1. This is simply false. Not only is it not the case, but this would be too lean in most scenarios where an engine has to live a while. On occasion, I've run into tunings where under some conditions, an engine
might see 14:1 ... and that's pretty damn lean.
While I generally find the US MCN to be about the best moto rag on this side of the pond, like RRW, it can be pretty amateurish at times. That's OK, still good stuff.