Changing years of a Megasquirt
 

If I wanted to, could I convert a MS3 configured for a 96-97 to a 90-93 simply by changing the pins in the denso connector? Obviously I would need to change settings in Tunerstudio but I'm just wondering if besides settings and pin location, if there's anything different between the na versions of the MS3?

the difference is only in the harness.

So I would only need to change the harness coming from the ms to the denso plug? Sorry if that's a dumb question, just making sure.

the 96-97 has three plugs, the 90-95 only has two

In that case, for the na pnp versions, is the only reason DIY sells different years is because the base tune is different?

Go to mellens.net and get the wiring diagrams for each car. DOCUMENT and UNDERSTAND everything you need to change prior to starting.

no, the wiring between the 90-93 and 94-95 are different enough.

the break down is 90-93, 94-95, 96-97, 99-00, 01-02, 03-05

Thanks for the info guys!

I know exactly how to do this and I would never, ever do it.

Can you elaborate on that?

Screwing with the factory pinout like that is just asking for trouble. At some point in the future, SOMEONE will assume it's still the way it's supposed to be and plug in the wrong ECU and boom.

If you want to run an ECU with the wrong pinout, make a short extension harness that reroutes the wires.

--Ian

I may be misunderstanding all of this. I was under the impression that there would only need to be changes to the Ms to make it compatible with my model year. Is this not the case?

Which MS3 do you have? MS3pro, MS3+MS3x, MS3, MSLabs MS3, MSPNP Pro? This will significantly impact how easy/hard/possible it is to change. If it has a patch harness from a DB37 to Denso connector, then yes, you can modify that harness. If it's a PNP, then it's more trouble than it's worth.

Maybe I should have clarified that in the beginning, it's a MS3+MS3X with denso to db37 breakout.

Check out this build manual that Braineack put together: https://trubokitty.com/#/ms3xassembly

You'll see that the building of the board is common between Miatas (other than a few mods for NB stuff, I forgot if there's any other changes between years), and the bulk of the differences is in the patch harness.

yeah, just build a new harness.

Thanks for the help!

You can't easily move pins around inside the ECU because they generally use a solder-on, board mount connector. It *is* possible, but it's going to involve a bunch of work with a soldering iron.

Moving pins in the factory wiring harness is relatively straightforward, you stick a tool in the back of the connector, release the catch on the pin, pull it out, and insert it into a different hole. It's just that you've now laid a land mine for the next guy who works on the car. :)

--Ian