RomRaider

Well ive tried searching and just going through this sub forum and no luck.

Do we know the algorithms Subaru uses for stft and ltft in the 32 bit ecus?
Say for example the 04 sti ecu.

Im curious to know what the forumlas are.

I confess that I haven't looked at the code for this, but if you're familiar with PID feedback, the ST trim seems to be the P term and LT trim is the I term.

I'm pretty sure the short-term trim is basically just "(TargetAFR - ActualAFR) * Gain" where the gain is just a constant that keeps the corrections at a reasonable level - high enough to get AFR close to target, low enough to avoid overshooting and oscillating.

The LT trim acts conceptually like a PID loop's I term, moving up and down with sustained positive or negative ST trims, but the code is probably more complicated. With a simple PID loop, you'd see them adjusting constantly by small amounts. But the values seem to be stable most of the time, and then once in a while the ECU decides to spend some time adjusting them. It's weird.