Maf is a mass air flow, It measures mass with a heat element being cooled. It is supposed to compensate for temperature and pressure, however humidity kind of screw the reading. However in the code there is only baro correction and some temperature correction for subzero temperatures. The corrections might not be output related but different engine requirements at that range.It also updates so quickly that gm put some smoothing routine to compensate for rapid changes.

The TPU outputs 4 maf values and eside gets an average of them for final calculation. It uses the raw TPU output for a maf table lookup and takes the value from table and interpolates between 2 adjacent cells. The first byte of RAW output is the vector for the table lookup and the second byte is the interpolation factor 0-255 or 0.01-0.99.

I will try to find a 68hc11 pcm to run a custom code for opti simulation. For variable rpm output I think a table for 1 high res pulse vs time vs rpm needs to be done and low res will just follow the high res.