rangerruck

I have seen a few mods, to move the gear 1 click counterclockwise, inside the afm, on a 22re engine, if you have heavier aftermarket parts and such, or if you live in higher altitude, to get a bit more power, or a bit richer fuel mix.
I am wondering the opposite; I live in Houston, about as low to sea level as you can get. what if, and I have pretty much all stock parts, I moved that gear one tooth clockwise? would I then get a bit lighter fuel mix, and thus improve gas mileage? Has anyone tried this? should I be a guinnie pig?
I figure toyota probably set this at the factory, for middle of the road, middle of the country type elevation, or even a bit higher, figuring in the time of the 80's, they would sell more in the west, upper west, northeast, as opposed to the deep or coastal south.

abecedarian

The O2 feedback loop keeps the air-fuel mix within check under most circumstances, regardless of altitude- particularly at cruising speeds / throttle positions. The ECU can even adapt to altitude changes via its "fuel trim" setting, which is a more coarse adjustment to fuel delivery than the O2- if the O2 sends a consistant lean or rich condition, the ECU will adjust the "fuel trim" accordingly in order to bring the O2 back to an approximate 50% duty cycle. Changes in altitude will cause the O2 to read such conditions- consistantly rich or lean until the trim is adjusted and compensates.
It's only at the far extremes, like with a cam that doesn't develop a lot of vacuum, or when lean or rich at wide open throttle, that the AFM should be considered a candidate for modification since the system uses the O2 for correction at most any throttle position other than closed or wide open.

rangerruck

so then, to go the other way, even if I change out the air intake duct, to a larger size, and go with a bigger filter, the O2 trim will still figure this out, and so no other settings need to be changed, correct?

abecedarian

Overall, the O2 and fuel trim should be able to adapt. Unless you have a modified engine.

TNRabbit

I'm running 210 psi on my 3vze and had to richen my mixture via the VAFM adjustment by 3 clicks.

Team420

I dont see how this could do anything in the long run... it may help at first, but eventually, the ecu will adjust the mixture to where it should be via o2, tps, etc... Right?

TNRabbit

Depends on what modifications have been done.