Nanufacture of this stacked injection ?

[olddog]

Originally Posted by FUNFER2

The "self learn" is a trial to make tuning easier, but what I hear from engine builders and seasoned vets of the old school guys, is, they don't have the system worked out yet, as they still have problems to be worked out. That's why so many give up and go back to carbs.

Self tune is a marketing ploy. Ford and every other manufacturer uses O2 sensors to add or subtract fuel. Different OEM have different methods, but they all basically accomplish the same thing. Most OEM, if not all, use narrow band O2 to dial in the fuel trims. The narrow band O2 is only used at light loads, when Lamda is near 1.0 (14.7 air to fuel ratio).

The aftermarket guys toss in a wide band and claim now we can self tune at all conditions. True enough, but if you correct at light loads, you will be correct at heavy loads, as it works for the OEMs. So did they gain anything with the wide band? Maybe maybe not. The reason the OEMs use narrow band is that they are more accurate and long term much more reliable.

Now all this self tuning is about getting the fuel to actually deliver what was asked for. It does not tune or change in any way what is asked for. What is asked for is the most important part of tuning the fuel. Well, a 14.7 AFR gives the least emissions, leaner better fuel mileage, and ~12.5 the most power at WOT. If you run 14.7 at WOT the engine melts, assuming detonation doesn't destroy it first.

So if at heavy loads the engine pings, you may want to richen up the fuel or pull some timing. These self tunes do nothing for this. Timing is where the power is at, and they want to tell you that one timing curve runs all engines. Well it will if you use modest timing for the engine that is most prone to detonation, and all other engines will leave power on the table and waste fuel doing it. Well a knock sensor can be used to pull timing, but it just yanks out a bunch to save the engine. It does not experiment and add a little back in at a time until it hears a ping and then back it off. At least every system I have read about acts that way. It would be possible to do, but I have not heard of any doing that. Not that I know everything.