Originally Posted by MalibuJack

We'll have to wait for someone from TurboXS to chime in to clarify this.. I'm not certain if you've mentioned if you had a UTEC or not, but when you run the dashboard, it very clearly indicates whether its running in open or closed loop, there is a log level that does record some alternate digital signals and some bit signals (on or off) I honestly can't tell you if they indicate open/closed loop in that log simply because I don't recall. There's definitely an indicator of whether or not its running open loop or closed, how it determines that is irrelevant, but how the UTEC acts when its aware of each state is what we're trying to figure out right? (Regardless of whether there's a real signal or not we do know its something calculated or indicated by the ECU since a scan tool does indicate it, and the UTEC is certainly aware of its state)

I do agree with most of what you said about how the closed loop fuel operates, and when your dealing with very large injectors, it makes perfect sense since you run out of adjustment in the trims.. Thats not really the debate here.

However what I am trying to establish (and figure out to some extent) is if the open loop functionality (the UTEC OLF feature) ceases to function below the crossover point, and if below that it alters MAF value only, or if it intercepts the signal from the ECU and scales the injector signal accordingly regardless, or it only acts when in open loop and directly controls the injectors from a background map.. (I tend to think that its operating on MAF frequency below the crossover threshold)

This is obviously a technical detail that none of us has any real info on so we'll have to wait and see.

With all of that said, I have to agree that it really seems to be mostly a "Tweaking" issue and for the most part, is just a learning curve since the background "Map" in the OLF feature is designed around a stock ECU, therefore if a reflash makes alterations that alter the duty cycles, then the background map would be out of sync and cause a jump on transition (Therefore a hiccup) At that point its really just a bit of tweaking.

Originally Posted by tlcoll1

My impression of the UTEC was that it always drives the injectors itself. If this is true, then it has the option of reading the stock ECU's injector drive signal and offsetting from that amount, or to drive it completely independently. So, if the stock ECU was using a 2 ms injector pulse width at idle, the UTEC could let the user subtract 5% from it, or allow the user to specify "always use 1.5 ms at idle." If this is the difference between "open loop fueling" and whatever "non open loop" is called, then I can see how it'd be really tricky to get this switchover point correct. Additionally, it seems like the switchover would vary with temperature, octane, etc, and be all put impossible to get right. This is only conjecture, though - as you said, it'd be nice if someone from TurboXS would explain how it all works.

And no, I don't own a UTEC. See my home page for why.

Tom