Is this really knock???
 

Gents,

I'm going through every parameter looking for clues as to the loss of sync. Could someone take a look and tell me if this is really knock.

Also, graph 4 is the VSS. It's really ragged. Do I have some kind of ground issue?

Thanks,

I doubt you have a ground issue. All your other sensor signals look super-clean. Now MS does do a lot of smoothing on the analog inputs, so we can't be certain, but I really don't think its ground.
My money would be on crank or cam sensor.

VSS is a digital input. So you either have the input or you don't. So if your speed randomly drops to zero then you might have a ground issue, but I doubt it.

Your lost sync reason is 32. Which means the megasquirt didn't see the cam signals.

https://cimg1.ibsrv.net/gimg/www.mia...a103c74209.png

https://www.miataturbo.net/megasquir...reasons-43775/

So dead cam sensor, improperly adjusted pots, or bad cam sensor wiring.

Thanks much. But is that really knock? It looks like it's happening all the time.