duffman: "Pull the map off the second link."
Those are interesting links, thanks.
I think I can't really use that map directly, because it's showing current, not voltage. I'm reading voltage. I suppose if I was less electrically illiterate I could measure the resistance of something and use Ohm's Law to do the conversion. But I think I don't really need to know the precise AFR, expressed as a ratio. I think it's enough to know if I'm lean or rich, and I can precisely monitor (at least in a relative sense) the gradual change from one extreme to the other.
"I thought you were trying to optimize a P&G scheme to reduce pumping losses?"
I'm trying to better understand the tradeoffs between light throttle (which has the benefit of lean burn) and WOT (which has the benefit of minimal pumping losses). I'm also very intrigued by the possibility that WOT is optimal, and better than 70-80%, despite what I've heard about the penalties of open loop. I'm generally intrigued by the possible benefits of WOT, especially because I don't see it mentioned much as a FE technique. It seems so counterintuitive.
"Regardless if you look at a BSFC map of nearly every gasoline engine FE is never at a maximum at WOT"
Metro made a very good point, that optimal BSFC is not quite the same thing as lowest overall fuel consumption. But aside from that, I don't know your basis for claiming that WOT does not optimize BSFC. The article I cited earlier has a helpful graph:
http://www.autospeed.com.au/cms/gall...0&a=110216&i=6
That graph indicates that WOT does indeed optimize BSFC. That's why the text says this: "At 100 percent load (ie wide open throttle) this engine has a minimum SFC."
But then I start to wonder if open-loop is still an issue, somehow. But consider the following observation. I'm climbing a grade at a steady 30 mph. Top gear, about 1200 rpm. WOT. The injector duty cycle is about 10%. That seems to be not very high, and the change, as I open the throttle more and more, was quite linear and gradual. So I'm getting the sense that I never hit open loop, even at WOT.
"the 80% that Johnny told you would be a good place to try"
I'm having a hard time finding objective proof that 80% is better than 100%, especially given what's stated in that article.
"there will be a point that it will move into the rich region, that should be after the 80% throttle mark"
Actually, the transition from lean to rich comes much sooner than 80%. It happens at about 25%. So I'm basically comparing the following two scenarios:
A) Cruise at a steady 55. RPM is about 2000. Throttle is about 10%. AFR is quite lean. Definitely in lean-burn mode. I haven't checked the injector duty cycle in this scenario, but I figure it's about 3-5%.
B) Use P&G, from about 45 mph to 60 mph. WOT, whenever the throttle is used. During WOT, AFR is very rich. Injector duty cycle is about 14-17%. (That's also kind of a guess; I haven't exactly measured that yet.)
I guess what I'm realizing is that I can basically evaluate A vs B by comparing the two injector duty cycles, and seeing how that ratio compares to the P:G ratio (i.e., the amount of time I spend in WOT, as compared with EOC, or neutral-coasting).
But I'm becoming convinced that P&G wins, and that WOT is optimal, and that lean burn should be given a chance to happen only when for some reason P&G is simply not an option.
"once you move into the rich region it is physically impossible to burn all the fuel"
Right. But I think the pumping losses offset this. In other words, WOT does such a good job of cutting pumping losses that it's worth using a rich mixture that doesn't burn all the fuel. Or at least that's my naive theory, at this point.