Red82GT, no, since the computer has learned to drive on the street. Once you start doing WOT runs the computer will relearn to make peak power. It's kind of cool and kind of a pain. We'd all like to be able to lock in our best performance settings and tune it between runs. That's just not how it works.
withamc, as far as the page goes, it covers adaptive strategy. Mach 1 and I disagree as to whether or not adaptive strategy applies to open loop operation. We both agree that it does in closed loop. I'll try to point you at specific passages.
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Example: suppose the oxygen sensor keeps sending rich mixture (go-to-lean) signals as short-term correction under certain rpm/load signals. The control module notes these repeated short-term corrections, and shifts the base calibration for that rpm/load combination toward lean.
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I added emphasis to "base calibration" because these are the numbers that are used in the formulas to determine how long to open the injectors. These same base calibrations are used in the open loop mode, too. I think we can all agree that you're running in open loop mode when you're doing the 1/4. If adaptive strategy doesn't apply why would the author say this in a sidebar?
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Drivers who drive their adaptive-system cars to the drag strip are often puzzled about their high Elapsed Times. The system adapts to street driving. When they run the strip a few times, the control module re-adapts to the strip and their E.T.s improve.
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Sorry for repeating that one.
This statement supports my response to Red82GT. It also clearly states that adaptive strategy even works during open loop mode. The computer doesn't simply revert to a bunch of hard coded tables at WOT. It uses different lookup tables, but they're still adapted to the base calibrations that are changed during closed loop and even open loop mode.
There are other things that will change with fuel pressure that I really haven't mentioned in the past, but it's already difficult trying to get people to believe the stuff we've been discussing above. Let's say you have 30# injectors and are having trouble passing emissions (especially HC and CO). You should lower your fuel pressure down to a point that they perform like 24#ers (about 31psi). The reason you would do this is that the injectors have physical limits as to how fast they open and close. The bigger the injector, or higher the fuel pressure, the less control the computer will have at idle. When the computer attempts to open and close the injector at a faster rate than the injector can handle, it will simply meter more fuel than the computer wants, and, therefore, run rich at idle. Too low a pressure may actually affect the spray pattern.
Like I've already said, I have my fuel pressure at 47psi because I am making more HP than the 24# injectors can support. I had definite fuel starvation problems at 39psi. Even at 45psi it seemed to lean out a little too much. 47 seems just right. The thing that hasn't really changed is my gas mileage. If I were to accept what you guys are saying, why wouldn't my gas mileage be significantly worse? Do you get better mileage at 33psi vs 39psi?
Dyno shops probably don't tell people that tweaks of computer controlled cars are worthless because they want your business. Also, some of the older computers may not use adaptive strategies, or at least ones that are as strict.
Didn't magazines start all the BS about adjusting the TPS to .999 volts? Our experiences, however, are different, aren't they (.94 to .98 is sufficient)? I suppose some will still swear by TPS adjustment still, but it's clear to me that if they can be wrong on the TPS they can be wrong on other things, too.
I don't know if you guys can tell, but I really love these types of discussions. The most important thing that any of us can do that will help us make our cars go faster is by knowing how they work and what we can change to improve them. It will also save us from spending money on gimmicks.
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351W 89 Mustang GT Convertible