As I pro tuner, I read Megasquirt on the board and knew it was a LINK of sorts ;)

Well duh the phono jack is a tuning port... I knew that the second I opened it..

Im not seeing the opto isolators or a vr on the board? What am I missing there because all the ms I have built just use the standard opto or vr circuts.

The guy I bought this car from had basically no clue what a turbo was let alone a megasquirt was.

Also. Im going to replace the phono with an rj45 the same way I modded my lc1.

Oh. Remember what code base he was on? I will probably end up swapping over to ms extra if I can or need to. I have alot more experience with extra and I want fireball antilag for the fun of it.

it's running spark as a complete standalone, therefore it must be on extra.

more than likely it's on 10_hr; a simple connect with TS would confirm this.


enjoy blowing up the car.

Wait what? Blowing up this car? What do you mean?

So I take it im still just blind and cant see the crank trigger components?

He's saying you're asking questions that would be extremely easy to answer for yourself if you knew how to hook a laptop to it.

So sue me for making conversation. .. im at work and I wanted to know if I should try to connect with ts or mt... my tuning laptop with both recently crashed so ill just put ts back on my new machine.

They are on the bottom of the board.

The crank signal goes in the opto circuit (U3, not visible) and the cam signal goes directly to JS10 with a 470ohm pull up to 5v. It's running the 4G63 trigger wheel decoder

why do you need to see them?

There are a number of different ways to handle the crank and cam inputs on a Megasquirt.

My own preference is to use either a MAX9926 chip or a circuit based on a dual-comparator such as a TL082 or LM393, derived from work done several years ago by AbeFM, JasonC and myself. Such typologies afford the best opportunities for noise filtration, proper implementation of adjustable hysteresis, etc.


Historically, it has been common within the MS1 / 4G63 community to use the stock opto circuit (with a pullup) to handle the CKP signal, and to apply the CMP signal, with a pullup but without any isolation, to pin 11 of the CPU. Again, this is not my preferred method, but it is the one historically practiced by the community and endorsed by DIYAutoTune: https://www.diyautotune.com/tech_art...azda_miata.htm

So that's what you've got here. It's an ancient design which lacks proper isolation and input filtration, but it seems to work for about 90% of users.

Thanks joe. Im not the best when it comes to inputs just yet so new concepts like that are helpful when explained.

I spent 2 days trying to get the stock 3.0 vr circut to read my honda missing tooth distributor setup without any luck... so any information I find on the subject helps better my understanding. I will be setting it up with an aem epm trigger now to delete the distributor and go cop.... my current plan is to use stock 3.0 opto input and another add on using a similar opto isolator to read the 1x wheel... are you suggesting I can use the output from the 1x wheel unfiltered?

Yes, that much is obvious. :giggle:


1: You don't need an AEM EPM trigger (or any other aftermarket device) to go COP.

2: Your car does not have a distributor. It has two ignition coils wired in a wasted-spark configuration. EDIT: Oh, wait, are you talking about the Honda here?


I'm not exactly sure what you mean by "1x wheel."

And, as someone who has spent a lot of time working with input circuits on the MS in a Miata context, don't waste your time duplicating the stock opto circuit for a second input. If you're gonna build a non-stock input circuit, do it right: https://www.miataturbo.net/megasquir...ircuits-25789/ EDIT: I assume we shafted back to talking about the Mazda again.

Sorry I wasnt clear enough but I totally switched gears to talk about my honda.... I have a megasquirted miata already lololol. :) ")

Thanks for the help on this though I really do appreciate it. The reason for the distributor delete was mostly due to the fact I cant make it stop leaking oil :(

The aem epm had a 24x and a 1x wheel. 4 wires. 12v+, ground, 1x out and 24x out.

Nope I understand the mazda vaugely enough that I know what I want to research to understand it better... I plan on finishing up the cop honda ms2 build here next week... I still have a few relay outputs to build as well as the ls1 coil plug wires and logic outputs.

I gotcha.

I'd remove the distributor from a B engine just on general principle- they offend my sense of style.

And yeah, that AEM unit will work fine on any MS using the generic toothed-wheel decoder setup page, for any combination of batch / sequential injection or ignition you can come up with. 24T is kind of a weird one, but the Wheel Decoder Spreadsheet will give you everything you need, once you determine the angular alignment of CMP relative to the crankshaft.

Cool. I already mocked up the ideal 1x location and wrote down the angles. Running some 1200cc injectors so im excited about sequential.

Looks like ms1 does not support fireball antilag mode.

Its been a long time since I've been on the forum...Hi old friends!
I know this is an old thread but I stumbled across it with some random browsing :jerkit: and felt compelled to reply.

For the record, I never cheated in auto-x:fawk:. I came up with the wiring scheme, and took Brain's help in wiring this ECU originally to be legal in the old STS class (I think). I quickly realized that getting around the "stock AFM rule" was going to be very difficult if not impossible with my electronics skills at the time. So I turbo'd it and had a hell of a good time after that in one of the prepared classes (I forget which exactly, maybe AMT). Won several events and legitimately beat the crap out of much more expensive and well prepared STi's, EVOs, Corvettes and one time, even an Elise.

It looks like this car changed a few hands after I sold it in 2011 or so, but I'm happy to see that it's still running well after all these years. It figures, I spent a shitload of time tuning it and tried to account for every possible scenario with the fuel and idle control maps, with the exception of altitude (not many hills in MI).

Oh and just as hindsight, my total budget for the turbo project was $1k and I came out slightly behind, at $813.89 for the turbo parts and ~400 for the ECU. :)

Anyway, good to see you all again. Back to my cave. Ciao!

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