Are STFTs non-volatile?

[leres]

Or do they reset to 0.0 when the PCM is booted (e.g after turning the ignition off for 15 seconds)?

I'm trying to use STFTs to calibrate my MAF and I'd like to collect a week or two worth of data (with LTFT updates disabled) and then make some changes. Aggregating data from multiple runs won't be very useful if the STFTs get zapped when the car is shut off. It looks like they are preserved (just like LTFTs) but I thought someone familiar with OS internals could confirm this for me.

I've also been thinking of an alternate way to do MAF calibration. You would leave STFT and LTFT updates enabled and drive around for a week and then collect a run or two of LTFT data and use a MAP to look at that vs. MAF frequency. The idea is to let the PCM do your data collection, filtering and reduction and then harvest the results and feed them back into the MAF calibration. Does that seem reasonable?

[mistermike]

Short trims aren't memorized by the PCM, AFAIK. They're a real time adjustment. If they start to go outside a certain range, then they'll influence the LTFT's which are memorized, unless the PCM is reset or trims are cleared. For logging shorties, just build a map with STFT's as data plotted against RPM and kPA using the same scales as your VE table.