2 gen long term and short term fuel trim?

when setting up a safc 2 with a logger do i want both ltft and stft set at 0%? and if your a positve number then your lean? how should i set this up?
thanks
tyler

and if i download this free software called ODB gauge at http://www.qcontinuum.org/obdgauge/ what is the source code that you have to download too do? do i need this?

Regarding your first post, you want to get LTFT to zero. STFT will give you an idea of what the ECU is shooting for however. If STFT is very positive for example, you can expect LTFT to also go positive over time as the STFT average is dumped into the LTFT. If they are both near zero, they will probably stay there. STFT can wander around though as the ECU adjusts for temporary fluctuations in the motors operating conditions. But again, the short version is that LTFT is the one to get close to zero.

so dont worry about the STFT? and should i run the LTFT at 0 or run it positve to run a little lean for more power?

so dont worry about the STFT?

I wouldnt exaclty go that far, reread my above post. :)

and should i run the LTFT at 0 or run it positve to run a little lean for more power?

The whole point of the trims is that as long as they are not maxxed out (the ECU still has adjustment control) AFR is NOT affected. In simple terms, anything between plus 12.5% and minus 12.5" will result in the same exact AFR in closed loop operation. Its actually more, because you can add the STFT to the LTFT , but you get the point.

so dont worry about the STFT? and should i run the LTFT at 0 or run it positve to run a little lean for more power?


The FT's tells you what the ECU is doing to compensate for a rich or lean condition based on the input it is receiving. Setting the LTFT is so you have the maximum adjustment range on the SAFC. Set your trims on the low throttle table then copy thoses values over the the hi throttle tables. Then we can start dealing with WOT pulls.... :naughty: .

so if its a positve # then the ecu would be adding fuel because its lean? lol sorry!!

Yes, exactly. So whatever the ECU is doing, you need to duplicate with the AFC or similar. If the ECU is adding 5%, try adding 5% with the AFC. Etc.