[technothrasher]

I had some fun a few years ago developing a replacement circuit for Ferrari 308/Mondial ignition ECUs, and then subsequently the ones for the 328/Mondial 3.2/Testarossa cars. It was interesting to see how crude but still effective the original circuits from the 1980's were, but also how much polish I could give to it while retaining form/fit/function compatibility, using an ARM Cortex-M0 and other modern ICs available to me.

One of the biggest updates I was able to do was to add a much more rugged power supply. The original boxes get fried easily by dirty jump starters, pulling the alternator while running, etc. It was pretty easy with the components available now to make a new circuit that protects from all that.

The most interesting thing to me was that when I went to a more modern ignition map rather than the crude 8 stepped curve they had originally implemented, while testing showed it produced more power and better emissions, people beta testing for me reported it felt 'too smooth, less fun'. So I went back to the original crude steps <shrug>.

Anyway, it was an engaging project that taught me a lot about engine ignition, and I've now sold about 100 boxes and helped keep these old classics on the road.

[vctrnk]

I'm still looking for an open ECU focused only on old, carbureted cars. Projects like Speeduino, rusEFI, MegaSquirt, etc. are wonderful, but I have no use for them because they're more geared towards fuel-injected engines (though some do have ways to run injector-less).

Case in point: I have a Renault R5 GTL with a Renix pseudo-ECU module [1] taken from a Renault R11 TX, along with its camshaft, head, double barrel carb and other bits. It has inputs only for manifold vacuum & crankshaft sensor (some support a knock sensor, mine does not). A crude ROM map is applied to the advance curve from just those two parameters. It works really well, but that's it, no way to change or fine-tune anything.

> while testing showed it produced more power and better emissions

A customizable "ECU" similar to the Renix approach that does EXACTLY this, would be a godsend to me (and also my local old Fiat/Lada/you-name-it heads). At these small displacements, we just don't care how the engine sounds: every HP gained is a win.

[1] http://boursinp.free.fr/pdgdiag2.htm

PS. Yes, I know an 123ignition dizzy is what I need, but they're way too expensive - and proprietary. Where's the fun in that?

[technothrasher]

Electromotive sells a waste spark system they call "XDi" that seems to be the go to replacement ignition system for the earlier carborated Ferrari folks. Perhaps something to look at if you haven't already?

> and also my local old Fiat/Lada/you-name-it heads

If you've got any Fiat friends who have a car with a Digiplex ignition system that needs a replacement, my ignition units will work with many of them as well, as the Fiat units are basically identical to the Ferrari units but with different curves in them. I've never actually sold a unit to a Fiat customer, but I do have curve information on several Fiat and Lancia cars. The exterior boxes are 100% identical, and I've used some of the Fiat boxes as cores before (I use the old boxes to make the new units, as sandcasting new replacement aluminum boxes would be way too cost prohibitive)

> 123ignition dizzy

I've heard good things about those distributors, but I've never played with one myself. I've used the Petronix solid-state triggers to replace points in a distributor plenty, but several of my mechanic friends now use the 123 ignitions instead.

[dicknuckle]

Don't even need Pertronix. You can use a TFI module from 1990's Ford vehicles and trigger it directly from the points distributor, or build a simple circuit with 1 transistor to invert the signal and trigger an HEI ignition module.

[technothrasher]

This is true, but the Pertronix units are cheap, easy to install, easy to remove and put points back in, and readily available. The downside I've found from them is that their reliability isn't perfect, but they're definitely better than points!

[dicknuckle]

An OEM TFI or HEI is even cheaper and more reliable. If you splice everything with bullet connectors and keep the points coil with you, it's the same thing to go back to points, with no tools.

[bayindirh]

There's at least one Speeduino based model aimed at carbureted cars:

https://wtmtronics.com/product/carbumate/

[geocrasher]

Check out this guy. He built what calls a "carb cheater". It's a Chevy Idle Air Controller (IAC) from a TBI setup, and is essentially a very controlled vacuum leak. Using it, he's been able to get some pretty impressive feats done. Might be the level of hackery you're looking for. It doesn't do timing, but this is the right kind of tinkering you're looking for, I think.

https://www.youtube.com/watch?v=FwhMz2kR4pw

[rainbowzootsuit]

You can use a single injector at the intake—Throttle Body Injection (TBI)—to replace the carburation metering with a fuel injector. A lot of domestic manufacturers did this for a time when they were struggling to convert to EFI.

For the MegaSquirt (at least) the default metering is speed-density which sounds like what your Renix is, and this is the minimum needed to run the MS, unless alternatively you go for Alpha-N fuel mapping.

https://www.holley.com/blog/post/fuel_injection_fundamentals...

[camhenlin]

I'm currently working on replacing the factory KJet on a 83 308 QV engine that's been swapped into a 77 308 GTB to a MegaSquirt 3 unit, with coil on plugs from a newer Corvette. Full fuel and ignition mapping control! It's been relatively straightforward so far, someone even makes a crank trigger setup for these cars, I've mostly just worried about keeping the work tidy. I am planning on adding a Rotrex C38-71 supercharger once the modern fuel injection conversion is complete.

[technothrasher]

Converting the 308 to full MPI is a great project, and I've seen some folks who have done really nice work in that area. Supercharging/Turbocharging them is also a fun project, but quite a bit more work!

[Zemtomo]

Just to be clear: you build an engine controller with a normal arm cortex-m0?

And if this thing breaks the engine just do nothing?

Did you build any hardening or redundancy into it?

[technothrasher]

If the ignition unit dies, the car will just turn off. I did add the power supply hardening, am using automotive rated components, and I'm actually able to ignore one of the three engine speed/TDC sensors in the car upon failure and still run, but other than that no redundancy. The original boxes do not have any redundancy either, so I'm still providing a "like OEM" solution.

[bayindirh]

I know at least one Ford ECU (1996 Ford Escort ZETEC) which has a limp-mode backup controller if the main ECU processor dies, so no, at least some ECUs have redundancies inside.

[technothrasher]

Oh, I'm sure a lot of engine ECUs have redundancies, probably most at this point. I was speaking toward the Magnetti Marelli Digiplex ECUs from the 1980's specifically. They have no redundancy.

[Zemtomo]

Cool to read about this.

I'm in Munich close to Bmw etc and whenever I did something with automotive it would say 'automotive grade components '.

I would not have assumed this would just work.

Is this also connected to can? Or is this only for old cars? So what inputs does it use?

[technothrasher]

It is only for direct replacement of the OEM ignition units on these Ferraris. The cars pre-date any kind of diagnostic bus. Although some cars of the era did have at least some flash code based diagnostics, the Ferraris really had nothing until the 348 came out in 1989.

[Gordonjcp]

Why would it need hardening or redundancy?

The original system hasn't got any.

[technothrasher]

I definitely gave hardening and redundancy some thought when designing. Just because the originals didn't have it doesn't mean it wouldn't be a nice thing to add. So I think it's a fair question to ask. But I decided it was mostly impractical for my design goals and price point.

[Zemtomo]

My experience with cars is not very deep but I did hear a lot about redundancy, isolated systems, real time requirements and automotive grade components.

Also I would say that controlling the ignition is very critical to a car.

[technothrasher]

Those are all important, but modern improvements. In the 1980's electronic management of engine systems was still very new to the scene and so most of the systems are still pretty basic.

> Also I would say that controlling the ignition is very critical to a car.

Indeed.

[Gordonjcp]

Yeah, there's none of that in car ECUs.

If something happens to the system that controls the ignition, it either runs poorly or stops altogether. No biggie.

[lemmiwinks]

> while testing showed it produced more power and better emissions, people beta testing for me reported it felt 'too smooth

How hard would it be to made that user-selectable? Because I would guess that some would prefer it that way while driving in the city.

Can you send CAN bus commands to the ECU?

[technothrasher]

I could have made a lot user selectable, added bluetooth connectivity (or CAN, I suppose), allowed uploaded maps, etc. But I wanted to concentrate on keep it simple plug-and-play for two reasons. First, the majority of people who own these cars don't want to fiddle. Their car died and they want to just swap out the unit and go. Second, I had some trepidation about the Clean Air Act of 1970, which basically says "don't screw with emissions". If I made it too easy for people to "play" with ignition maps, I was worried I'd be in violation of that law.

[ilyt]

Was there anything special in the cars that made off the shelf aftermarket ECUs not work with them ?

[technothrasher]

No, off the shelf ECUs will work. But because it is a mechanical fuel injection system on these cars, most of the applicable off the shelf ECUs are designed to copy an old two spring distributor system, so you'd lose a lot of the ignition map. Also, for any off the shelf ECU you'd have to hack into the wiring harness, because the OEM units use a proprietary 11-pin connector which is unavailable anywhere. I had to pay about $5000 to get a custom run of them made. A lot of people don't want to hack into their car because it lowers the value. There are definitely people who have hacked these cars with standard ECUs though, even going full electronic MPI fuel injection with things like MegaSquirt.

[rainbowzootsuit]

I definitely have no need for this, but do you have anything published about the project?

[technothrasher]

I don't, unfortunately. I've thought about writing it up but never got around to it.