MS3 Build Questions
 

I have purchased and began building an MS3 from DIY Autotune using the Megamanual (Assembly Guide - MegaSquirt(R) V3.0 Main Board). There are certain steps that require you to make decisions based on the vehicle. I can't seem to find anywhere which options to choose for the miata. Also I don't have an Ms3x, is it possible to do the build without one and what mods will this require? I have a 2000 with the stock 1.8 and I plan to use the MS as a standalone.

Doing it without an MS3 will multiply the amount of work you have to do by approximately 10x. Just ask @hi_im_sean

Read more. Franks guide should be out there somewhere. I think I have it hosted here too. http://sadfab.com/99-05MSGuide/99-05MSWestfield.zip

you want expander board.

follow frank's writeup. google "frank megasquirt"

I dont build the harness the way he does.

Thanks for the quick responses, I just ordered the expander. Just to confirm other than the harness I shouldn't need to order anything else, correct?

nope. ms3 kit + expander will run any 90-05 miata.

One more thing Brain, just a general question about forum courtesy; In the future as I undoubtedly will have more questions as I'm building the MS, is it better to reuse this this thread or start a new one?

wiring bundle for the ms3x is helpful.

Knock module is a good option to add.

One thing Frank's page isn't so good at is showing how he connects that 48-pin Tyco connector to the MS3. Anyone got any details on that?

Don't do it how he does it

I can document exactly how i build a harness this weekend for an alternative approach.

That'd be nice!

Start with a bored helper:

https://cimg2.ibsrv.net/gimg/www.mia...2e8172e849.jpg


Populate the Mainboard DB37:

https://cimg4.ibsrv.net/gimg/www.mia...1783c04993.jpg


Populate the MS3 Expander DB37:

https://cimg6.ibsrv.net/gimg/www.mia...f9f501c03e.jpg



Acquire an OEM Harness connector:

https://cimg7.ibsrv.net/gimg/www.mia...0464f22ff4.jpg


Chop off the top pins so they are about 1/4" long:

https://cimg8.ibsrv.net/gimg/www.mia...16a7c234b9.jpg


Bend up the lower row so they are flat (try to actually fold them back straight):

https://cimg9.ibsrv.net/gimg/www.mia...32b0ca8f5e.jpg


Cut them flush to the top row:

https://cimg0.ibsrv.net/gimg/www.mia...abfe19097c.jpg


Pre-tin the pins you'll be soldering wire to.
Put heatshrink on each of your wires. *SUPER IMPORTANT*
Pre-tin the wires.

https://cimg2.ibsrv.net/gimg/www.mia...eff7078ce7.jpg


Start soldering the Mainboard DB37 wires (I start from left to right, lower-rows to top-rows):

https://cimg3.ibsrv.net/gimg/www.mia...6ce56961bc.jpg

Follow up with MS3 Expander wires:

https://cimg4.ibsrv.net/gimg/www.mia...4efa3b7a06.jpg


Melt the heatshrink so you ensure no wires will make a connection:

https://cimg6.ibsrv.net/gimg/www.mia...cd2efd393d.jpg


Follow that up with hot-glue so the wires stay secure and are less prone to vibration & stress:

https://cimg8.ibsrv.net/gimg/www.mia...89612cb7ec.jpg


And done:

https://cimg7.ibsrv.net/gimg/www.mia...8e8019ac30.jpg



You can populate the center connector for inputs and output, I used to do this, but lost my source for pre-populated connectors -- i hate crimping pins

So I end up with something like this:

https://cimg8.ibsrv.net/gimg/www.mia...09931c62fd.png

Thanks so much, I'll be using your design for the harness now!

What is your source for the colored wires.

diyautotune.com

MegaSquirt Wiring Bundle – 23″ Long

https://cimg6.ibsrv.net/gimg/www.mia...7078d9d2a5.png



MegaSquirt 3X Wiring Bundle – 23″

https://cimg2.ibsrv.net/gimg/www.mia...aa5966551d.png