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SAFC newb question

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20+ Year Contributor
Apr 21, 2002
Bethlehem, Pennsylvania
Hey guys,

Well, I just got my injectors put in and I'm trying to adjust the Fuel trims again. I think I got it down but there is something that is confusing me. The STFT is the reading the ecu is getting from the O2 sensor and the LTFT is just a long term reading from the O2 sensor. Is that correct?

Ok, now say you have a +5% LTFT and a -2% STFT. That would mean that the ecu wants +3% more fuel right? Right now, after a nice hour long drive my LTFT is reading +5% in most of the rpm ranges. I should add some fuel to the SAFC so I can try and get rid of that right?

I tried searching but I never quite figued it out. Some people sayjust tune by the LTFT, others say add the 2 together. I would just like to know what people have found to work the best.

Damn if this is a Newb ? then i would hate to see an Advanced ?. :p
I just figured by the other stuff in the tuning section that this was newbie. If it's in the wrong forum I apologize :)
No not wrong forum but it just looks and sounds advanced.
the STFT is the O2 sensor correction. The LTFT is the ecu's memory of what you need at that specific RPM.

And, you are right, +5 LTFT and -2 STFT means that you are needing 3% more fuel at that RPM. So, add 1 or 2% on the AFC and eventually that RPM will even out to 0% LTFT and 0% STFT.
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