Idle mixture screw affects AFR?
#1
ERTW
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Idle mixture screw affects AFR?
Today i went to adjust the idle mixture screw, turning it about 1.5 turns IN. Now, maybe it is unrelated, but i was logging with my wideband and my AFRs seem to be about 0.5-1.0 RICHER. does this make sense?
if it is true, i am assuming the idle mixture screw is allowing LESS air in, even though the same amount is metered by the AFM?
this is on a stock ECU with SAFC-II doing fuel adjustments. i had it tuned pretty decent before around 13.0-13.5 AFR at WOT across the range, and now i am back down to 12.0-12.5.
if it is true, i am assuming the idle mixture screw is allowing LESS air in, even though the same amount is metered by the AFM?
this is on a stock ECU with SAFC-II doing fuel adjustments. i had it tuned pretty decent before around 13.0-13.5 AFR at WOT across the range, and now i am back down to 12.0-12.5.
Last edited by coldfire; 08-19-06 at 09:29 PM. Reason: ..
#3
Sharp Claws
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the variable resistor has nothing to do with how much air is entering the engine.. the adjustment overrides the AFM signal slightly and allows for some adjustability at idle for the mixture, what it does is tells the injectors to add or remove fuel and has nothing really to do with the air entering the engine.
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Hmmm, i adjusted this recently and it felt like i did lose a little power, would this be why? i adjusted it probably no more than a half of a turn. it wasnt a drastic reduction, but i was kind of confused when it happened. I have a bone stock 88 n/a, other than straight pipes to OEM mufflers.
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#9
ERTW
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hmm, well that was really the only thing i changed.
i will maybe go out and datalog, and see if it is still rich, and then try adjusting the screw and see if it makes a difference or not.
i will maybe go out and datalog, and see if it is still rich, and then try adjusting the screw and see if it makes a difference or not.
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