It still has that warning...just received my PC111 yesterday.......any more news on how to make the fuel changes?, as I am fitting a DNA ST.3 Airbox and Carbon Cans, and following shortly a custom map on the dyno, and so I am looking to get optimum "pull" throughout the rev range. ?

If it is possible to solve this, it doesn't sound like the solution will come from Dynojet. I emailed them about this last week and received this:

"We have no way to disable the stock o2 sensors without tripping a fault code in the ECU and causing the FI light to stay on. I do not know if/when we might have an o2 controller for this model. As long as the stock o2 sensor is running the Power Commander will not be able to tune the lower RPMs and throttle positions.

Let me know if you have any further questions."

Thats really useful to me, thank you Nazzurro.

So, does that mean that NONE of the O2 Eliminators will work without tripping the ECU on a 2008 bike? Seems like that.

Would the Kev fuel mod together with an O2 eliminator help with surging? Or does the kev fuel mod suffer from the same limitation as the pcIII when it comes to richening the fuel mixture at low revs?

The reason I'm asking is that if the kev fuel mod can help at low revs which the pcIII can't (together with O2 eliminator), then for me the kev fuel mod would be a better option than a pcIII which I was after in the first place.

I think that the Kev Mod and the PC111 basically do the same thing, the PC111 is more adjustable, but alot more expensive.They both allow you to alter the amount of fuel at a given time.

Yep, but they accomplish it using different techniques, so I figured maybe the result could be more effective at low revs with the kev mod as it just tampers with an input signal to the ecu. Who knows, maybe the ECU would consider the temperature also in low revs, and richen the fuel, thus lessens surging.

Just speculating... :)

best ask Kev!!!

The O2 sensor can be turned off as I have already worked out how to it &have done it, I have shared my findings with Dynojet USA.

I am still working on this new mod so it can be easy for others to install, at the moment it is quite complex to wire up.

It is very easy to keep the engine light off when the O2 sensor is disconnected, we have been doing it here on the forum since 2007.

This is what the surge looks like on my 09 XTX with the O2 sensor connected, at a fixed throttle setting while riding.
http://www.youtube.com/watch?v=ZwTfuwZZ848&feature=channel

This is the O2 sensor turned off at the same throttle settings. With the O2 sensor turned off you do not need a O2 eliminator.
http://www.youtube.com/watch?v=1Y9mqJtXtm4&feature=channel

All this information can be found in the Modification index

http://www.xt660.com/showthread.php?t=630

http://www.xt660.com/showpost.php?p=83237&postcount=10

Aha ok, thanks for that info, lets hope they make use of your research and provide us with a good solution!

So, have I understood things correctly: currently there is no easy way for me and fellow xt riders on 2007 an forward models to get rid of the effect the O2 sensor have on the fueling on low revs, other than switching to the older ECU including wire harness?

Running an O2 eliminator on mine with a PC3 and no problems am also running the map D.N.A sent with the stage 3 filter