Now that I was not aware of. Learn something new every day.

Ok, so say I wanted to do a 36-1 with a vr trigger. I would build the VR Circuit as per step 51 of the megamanual, and configure my jumpers as per Joes thread here: https://www.miataturbo.net/showthrea...t=20241&page=2

I would not have to remove any of the previous mods on my board because they would be disabled by the jumpers, correct?

One last question is which pins would I wire the VR sensor into on the megasquirt?

Ignore most of what I posted in that thread. I was screwing around with all sorts of different circuits.

Basically, you will build the complete VR circuit, and then set the following jumpers:

TachSelect - VrIn
VrOutInv - Tsel *or* VrOut - Tsel

The decision as to whether to use VrOut or VrOutInv depends upon the polarity of your VR sensor wiring, which is impossible to determine without an oscilloscope. So you'll have to just experiment and see which one works. Alternately, you can set the jumper to one or the other and then try flipping the wiring of the VR sensor itself. Same deal either way.



Correct, though I'd recommend removing any wire which you might have connected to JS8 and/or CPU pin 11.



One of the two wires will go to pin 24 of the DB37 connector, the other will connect to any available ground pin. This is the place where you may have to experiment with flipping between the two as mentioned above.

This is just the info I'm looking for, I'm glad I gained some understanding of VR vs. hall sensors in the process. I plan on trying this out after I finish my LNC 1.6 build as that wheel will be pretty much bolt on to that engine, not so much for my SN thats in there now.

Will I need to do anything else to get a tachometer to work on my 1990?

The tachometer in the '90 - '95.5 cars is driven directly by the ignition coils or igniter, so it's completely independent of the ECU. If the engine runs, the tach will work.