MS3 in 1990

I'm planning on building a Megasquirt 3 for my 1990.
I come from a backgroud of turbo Miatas. I built a DIYPnP for my Miata, which was very easy to just throw in and go. I then switched to RusEFI which was less PnP, however still very straight forward.
I understand however, that my 240 does not have a supported connector for the DIYPnP, so I'm on my own to build a harness adapter.
I searched for Megasquirt on the forum, but couldn't find anything that explained how to go about throwing an MS into a 240. I did find that people are Microsquirts. Why not go for the full Mega system? Is the ignition system an issue?

Ight noob, first thing to know is the search function doesn't work worth a **** on the forum. Use google and tack "turbobricks.com" on the end of whatever keyword or phrase etc you want to find. Like this:

https://www.google.com/search?q=how...rome..69i57.7506j0j7&sourceid=chrome&ie=UTF-8

Easiest way is to wire it from scratch. The 10’ harness leaves you with plenty of room to get it all wired, and they’re color coded and labeled every 6”

MS3 is overkill in a way, unless you plan to implement quite a few of the MS3 features. Enough to justify the extra $.

Otherwise I would use an MS2 v3.0

turbotankshane said:

Ight noob, first thing to know is the search function doesn't work worth a **** on the forum. Use google and tack "turbobricks.com" on the end of whatever keyword or phrase etc you want to find. Like this:

https://www.google.com/search?q=how...rome..69i57.7506j0j7&sourceid=chrome&ie=UTF-8

Click to expand...

Should've thought of that, thank you!

cwdodson88 said:

Easiest way is to wire it from scratch. The 10’ harness leaves you with plenty of room to get it all wired, and they’re color coded and labeled every 6”

Click to expand...

Labeled in what way? The harness in the car from the factory is labeled? That's new.
Mind clarifying?

Are you saying to create a harness for the whole engine? I've seen that suggested elsewhere.

Dirty Rick said:

MS3 is overkill in a way, unless you plan to implement quite a few of the MS3 features. Enough to justify the extra $.

Otherwise I would use an MS2 v3.0

Click to expand...

I could get a 3.57 for 300$, and wouldn't be too bad to assemble. Only reason why I said MS3X was because a lot of Miata owners use the MS3X and its fantastic tuning wise.
I had a DIYPNP which is MS2 based and it worked well. The MS3X was just a step above it in terms of fine tuneability.

I'm also looking into RusEFI. I ran that on my Miata as well and it's fantastic, especially the pricepoint.
I just figured that more people have experience running MS on these cars than a more obscure ecu such as RusEFI.

240 has horrible stock wiring, yank the stock engine harness out and build your own ms3 harness.

A v3.57 main board does not need any assembly, It is a pre-assembled generic basic system using SMT components.

A v3.0 board can be custom assembled to fit the configuration you need, it uses wire through hole construction and has a proto area to fab up extra circuits.

A MS3X is an expansion board built for the MS3 that you need to take advantage of the extra functionality. The MS3's functionality is its advantage, the tuning improvements are small.

You can use a MS3X with a MS2 processor and an adapter board but doesn't really pay off.

This is why the MS2 w/v3.0 main board is my go to setup. Price has gone up but it's still the best bang for the buck, still less than $300

Dirty Rick said:

A v3.57 main board does not need any assembly, It is a pre-assembled generic basic system using SMT components.

A v3.0 board can be custom assembled to fit the configuration you need, it uses wire through hole construction and has a proto area to fab up extra circuits.

A MS3X is an expansion board built for the MS3 that you need to take advantage of the extra functionality. The MS3's functionality is its advantage, the tuning improvements are small.

You can use a MS3X with a MS2 processor and an adapter board but doesn't really pay off.

This is why the MS2 w/v3.0 main board is my go to setup. Price has gone up but it's still the best bang for the buck, still less than $300

Click to expand...

https://www.diyautotune.com/product/megasquirt-ii-programmable-efi-system-pcb3-0-kit-w-black-case/

My mistake, it is a 3.0, the one I mentioned building. It's been a long day.

microsquirt because most implementations and owners don't actually need the extra stuff that comes with an ms3 based install. No building of a board, just wire up and go tune.

linuxman51 said:

microsquirt because most implementations and owners don't actually need the extra stuff that comes with an ms3 based install. No building of a board, just wire up and go tune.

Click to expand...

The Microsquirt does seem simple enough to make work.
After thinking about it, I might want to keep things in a sort of stock manner. Meaning, I'd like to be able to swap boxes, TPS sensors and drive off as normal.
Is that possible?
Unless I swap to 2x (instead of 4x) batch fire injector side, and sequential ignition (How does seq. work with no cam sensor? I've heard of a yoshifab plate which allows for a CAS signal), I should be able to go back.

I've got a welder, and some decent fabrication skills (built the exhaust from the turbo back in my Miata), so welding in an extra bung for WBO2 won't be a big deal.

I am liking the idea of the Microsquirt, my biggest concern is losing the stock functions of the car permanently. The idea behind my "build", is to have fun with the car for now, and then return to stock when I sell the car (tentative, but planned).

Also the Microsquirt is about the same price as a MS2 with a short harness on both.

Is there a source for the board side connector in the LH box and the EZK ignition box? If so, I can just have a "break out board" made with signals printed on the PCB.

Here is my thinking: Keep the stock harness as is. Add in a Microsquirt/MS2/MS3 specific sub-harness.