Basically, there is not enough variation in MAP pressure, and the rate of change is very steep off idle with no change at higher rpm. This means that the VE table is pretty flat.
Subsequently, I changed over to TPS based fueling, the result is a much more responsive drive, throttle response is like lightning in comparison, and it feels and sounds like its set up properly. The AFR is much closer to the AFR target. I've only ran autotune for about an hour or so on what was a relatively quiet drive, so the edges are not tuned yet, but for the most part its pretty close. Its certainly very drivable
Whilst I was trying to get Alpha-N working I hit a few idiosyncrasies in the tuning software. There are three fueling options for megasquirt: Speed Density; (MAP Based) Pure Alpha-N; (TPS Based) and Blended.
For now I'm using Pure Alpha-N, however when I set the fueling algorithm to Alpha-N in either tuner studio, or megatune it was still using MAP for fueling. For whatever reason it was using the blended algorithm. This seems to be not a bug, but slightly misleading name, Pure Alpha-N is essentially blended, but starting with Alpha-N rather than MAP. Therefore I set the Threshold to 9k in the Alpha-N blending dialog.
In addition, I had ego correction active at idle, this results in an idle which falls and rises all the time, setting EGO correction to be active above 1200 worked a treat.
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