New Power Commander S4RS

[Moronic]

CDawg, that is a beautifully expressed explanation and also happens to be the way I see it. From what I can glean, the PC modifies the info coming out of the ECU and sends the modified signal to the injector. But the modification is a fixed tweak on the stock signal. If stock signal is also fixed - as in earlier systems that don't read exhaust gas - then the combination of stock and PC is fixed to the modified value.

But on the newer bikes, the stock signal is affected by the exhaust gas reading. The PC may richen the stock signal by a fixed amount, but the feedback loop then leans out the stock signal on the next cycle to compensate - rendering the PC irrelevant.

My guess is that the stock signal ignores the O2 sensor above the 5250/19pc throttle part of the map. And hence becomes susceptible to PC manipulation.

Thought about it tonight as I was riding home from work (on stock ECU, which it seems makes me a rare case). It really does seem as though the surging disappears above a certain small throttle setting, even if revs are below 5250.

[vstryker]

...thinking about it, it doesn't matter because if you have value below 5250 RPM and 19% throttle, the stock ECU will just compensate and reduce fueling to get it back to OEM levels...so its not the PCIII is "locked" it just that the stock ECU compensates the PCIII values to get it back to stock level.

so would unplugging the O2 sensor disable the stock ECU to make changes for anything under 5250rpm and 19% throttle allowing the PC3 to do whatever it wants across the whole rev range? or is it a little more complicated than that?

[CDawg]

so would unplugging the O2 sensor disable the stock ECU to make changes for anything under 5250rpm and 19% throttle allowing the PC3 to do whatever it wants across the whole rev range? or is it a little more complicated than that?

1) the check engine light would remain on at all times
2) some shops have been able to make this work, others have not.  The stock ECU is not designed to operate w/o an O2 sensor, so there is no guarantee or consistency that it will work. See this thread for more detailed explaination: http://ducatimonsterforum.org/index.php?topic=655.0

[He Man]

1) the check engine light would remain on at all times
2) some shops have been able to make this work, others have not.  The stock ECU is not designed to operate w/o an O2 sensor, so there is no guarantee or consistency that it will work. See this thread for more detailed explaination: http://ducatimonsterforum.org/index.php?topic=655.0

Engine light is only on for 07+ bikes, (does the 06 S4R have an O2 sesnor? im not sure) The light cannot be shut of, most people just throw a piece of tape over it, or go inside the gauge and kill te light completely.

2) The stock ecu works fine without the O2 sensor, otherwise it wouldnt work if you unplugged it. I know from experience that the O2 sensor when removed from the S2R1k will have absolutely no problem. The only thing you need to do is reset the ECU by removing the battery and leaving the bike in the ON position for a 30 seconds or so. If u unplug the o2 without resetting the ECU, the bike runs pretty rough and will shut of randomly.

however i still dont know why not all ECUs behave the same way with PCIIIs, as Cdawg said, PCIII works fine with some, and not so good with others.