MS Assembly Help
 

Halfway through the steps, so far so good! I want to ensure there is no guessing on my part as I build this. I may have more questions along the way (I promise I'm searching as I go along, it's how I've gotten this far already! ;) )

What kind of tach signal does the miata use? What should I be doing with step 50?

Thanks!

MSI v3:
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50. Next you need to make a decision. There are two input circuits for the tach signal:

The Hall/optical/etc. circuit takes the square wave input from a Hall sensor, optical sensor, or points. It can also be used for triggering off the coil (but only if you are not controlling ignition timing).
The VR circuit takes the AC signal from a variable reluctor sensor and converts it to a square wave for use by MegaSquirt.

You'll use the VR circuit. You can build both like the manual states, or just the VR circuit for the CKP signal. If you have a MS3X use its VR input for the CMP signal, rather than modifying the mainboard. It's easier and a superior circuit.

Thanks for your response Stucky!

I came across this earlier today, and now I'm just as unsure as I was before :lol:

http://miataturbo.wikidot.com/ms-assembly

So, this is saying the VR tach input isnt used (and shows a mod in place of it, do i just go with the mod)? I have a 1991 1.6L, if it makes a difference.

The hardest part of building the MS3 is that there is not a single guide which you can follow from start to finish for the miata. You'll pull a little from here a little from msextra, a little from megamanual, a little from Frank's site, etc. Do some searches for MS3 in the megasquirt forum here and you should find everything you need.

I can't answer your specific question as I built my for a 1.8. For what it is worth I used the VR circuitry.

I understand everyone's frustrations when building a MS. I still remember mine when I built my first MS. That's the reason I'm doing the how-to's on my site.
They're not complete, but I work on them regularely. All info that should be added is welcome. I also welcome msq's for each how-to.

I mean, mine was/is pretty damn complete. It's just a tad outdated.

https://www.miataturbo.net/useful-saved-posts-8/how-make-install-your-own-diy-megasquirt-13676/


and I have one for the DIYPNP:
http://www.miataforumz.com/showthread.php?t=356


and the majoroity of my writeup is on the wiki page linked above with steps for the MSII. I just havent kept up with it.

Everything you need to know to build a MS3 is in the MS3 assembly manual. I see people bouncing around from one source to the other, and that causes problems. Most of the problems I see are people built incorrect tach circuits as shown in guides that are not the official MS3 assembly manual.

The MS3 manual is here:
http://www.msextra.com/doc/index.html#ms3

True you could just follow the msextra assembly guide. The msextra site really is quite good and has most everything you need. However following the guide verbatim will have you building a lot of unnecessary stuff if you have a MS3X. At least you'll know you have everything you need though!

I was able to get my car running on my MS3 (and MSX) by doing mostly searches. However this takes a ton of patience and isn't the most time efficient method. My bookmarked MS3 assembly list has roughly 15 webpages. Here are some links that helped me along, which are outside of the normal megamanual, msextra, and diy guides:

Freaky Roadster's Thread
Brain's recommended v3.0 population; Too lazy to find the original thread I pulled this from.
skidude's MS3 thread
Very helpful info about iacv operation once you do get it installed.