Originally Posted by soviet
For the second option (full sequential spark & fuel), you need to modify your CAS, correct?
You need some kind of cam signal to run full-sequential, yes.
If using a "generic" wheel (eg: 36t, 12t, etc) then to the best of my knowledge, the cam signal must be one pulse per revolution. Those settings which allow other styles of cam signal (eg: 4G63, 99+ Miata, etc) are all hard-coded in the software for those specific applications.
It's entirely possible that this has changed with the MS3- I honestly know very little about the software on it.
But going back to where blindboxx2334 came in, he has a couple of obvious options:
1: Use an unmodified NA CAS. (bleh.)
2: Use a 12t wheel with one tooth removed and run in batch mode.
3: Use a 12t wheel with all teeth intact, and add a cam signal by either modifying the plate inside an NA CAS or physically grinding two of the three raised bumps off of the intake cam pulley (this assumes he us using a stock or stock-like pulley and not cutting away the part of the valve cover which holds the sensor.)
Also I believe the crank sensor came on OBD2 cars, not just NBs. Because my 96 definitely had one along with a timing disk & thinner pulley boss.
The '96-'97 cars did come with a crank sensor, however both the sensor itself and the toothed plate which it reads are different from those found in NBs.
The NB sensor gives an open-collector squarewave output just like the NA CAS. You know this already, I assume.
The crank sensor used in the '96-'97 models, by comparison, was a raw VR sensor (two wires) which output a differential AC waveform. It was also physically somewhat different, and I believe that it mounted to the engine in a different location (I won't swear to that last bit, as I have only ever worked on one '96 engine)
The two are in no way compatible or interchangeable, although with the removal of two teeth (and the addition of a one-pulse-per-rev cam signal), the stock '96-'97 crankplate and sensor could be used with a Megasquirt, and I assume that the 12t wheel would also work with the '96-'97 sensor, albeit with the aforementioned qualifications.
Originally Posted by blindboxx2334
So you just use an oem miata crank sensor with the trigger wheel? It sounds nice and simple. I like.
I haven't personally run the 12t wheel that's recently become available- on my own build, I used an EDIS-style 36-1 wheel and fabricated a mount for it and the sensor.
But yes, it's my understanding that the 12t wheel is intended to be used with an OEM-style NB crank sensor.