3.0 + Ms3 + ms3x on a 94 (c pkg)
 

Just wanting some verification that I'm making the right decisions :)

I've got the 3.0 board built (followed the stupid ms3 instructions before I read about cam/ckp inputs being iffy) So last night I added the AbeFM circuit to the proto area, because I'm running the stock CAS now, but I'm planning to run a trackspeed wheel and 99+ crank sensor soon. Best I can tell this is the smart thing to do.

I'm planning to just build the standard LEDs, useless or not because there's an abundance of unused outputs on the ms3x (Going to run seq fuel, and wasted spark with COPs. spark and injectors from the ms3x outputs, obviously)

I'm thinking I can build the normally useless 3.0 fidle circuit and drive the fans with it, and then use one of the medium current outputs on the ms3x for the actual IACV.

Launch control and AC input to ms3x. VSS to the vr input on the ms3x? I don't remember having seen anyone talking about VSS w/ ms3 in a miata.

You have a ton of outputs available on the Expander, you really shouldn't need to run anything off a main board output (except the fuel pump) unless you just really want to. Cooling fans, idle valve, shift lights, pretty much anything you can think of, there's enough outputs on the Expander.

Cam input signal can go to JS10 like usual or to the Expander pin 32. The Expander has a decent conditioner (and pullup) on it, but if you've built a schmitt trigger, then JS10 would work just fine.

The VR conditioner on the Expander is for the cam sensor input. VSS can be input as a 0-5V analog signal or a square wave on several different pins, but not on the VR input.
I *think* for some reason the Miata VSS output found on the NA instrument cluster is a digital (square wave) output, but I've not scoped it before.

For anyone curious about VSS w/ ms3 in an na... I had great sucess with the following settings.

Datalog in via ms3x which has an internal pullup
(I think you need a pullup if cruise isn't installed, ymmv)
wheel diameter .577 (stock 185/ xx /14s)
speed sensor #teeth 3 (had to trial and error this.. weird number, but it works)

final drive, 4.10, 5 speed (stock torsen, etc)
3.14, 1.89, 1.33, 1.00, .81

I had to do something similar.

diameter .584
teeth 3

I dont think the teeth is gear teeth necessarily. it might be pulses per engine rotation?

Its just however that reed switch is setup. Just bizarre that 1 tire rotation = 3 of anything.

Saved

trying to get your post count up?

no, I told him to look for VSS settings for his ms3x.

No, if I wanted to do that I would just do this.