Speeduino – Arduino based engine management(github.com) |
Speeduino – Arduino based engine management(github.com) |
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.
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?
> 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.
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...
And if this thing breaks the engine just do nothing?
Did you build any hardening or redundancy into it?
The original system hasn't got any.
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?
https://megasquirt.info/history/
http://www.megamanual.com/MSFAQ.htm
I participated in the Yahoo group where the early development of this happened and had a car that my friend and I retrofitted. Bowling and Grippo deserve all the credit due for making this in a free and open spirit.
The original way one made the kit is to order a board in a group buy, and import a BOM .csv file to digikey to put together your own parts kit. It looks like you can mostly still do the same today.
Around that time a friend was having car problems. He described the symptoms to me. I looked up the type of fuel injection used on that car, which sensors it used etc, and recommended they replace a specific sensor, without ever having even seen the car- all based on my knowledge from Megasquirt. I found out later that it worked, the engine ran much better. It's amazing what a bit of open source knowledge can do :)
Then, to tune precisely to the engine, you datalog the oxygen sensor or fuel ratio sensor in closed-loop and process that data to refine the fuel map.
I'm harking back to Megasquirt 1 here so things might be a little different now.
Now if you go back in time far enough to pre-WWII designed vehicles it was common to have two ignition systems with a massive mechanical lever to switch between "magneto" and "coil" based ignition for gas engines in military engines. Coil driven spark plug systems had advantages but the magneto system was much more reliable by virtue of having no moving parts. Diesels had a slight advantage here in that there was no ignition system as such to fail.
All Audi and VWs recently have drive by wire system that opens the throttle, drives ignition coils, and triggers fuel injectors electrically. It’s not like there is much to go wrong. I did find a very high accuracy, temperature compensated Crystal resonator which makes sense for sending timing signals in a harsh environment.
It would involve a lot more than just an Arduino & some wiring obviously. And a lot of the car's charm is its low-tech originality.
* https://www.saveourracecars.com/about.html
* https://www.aemelectronics.com/product-legal-restrictions
* https://tiremeetsroad.com/2021/07/13/how-californias-bar-app...
I think I still have a spare MS hotwheels sticker around somewhere. [4]
[0] http://www.msruns.com/index.php
[1] http://www.msruns.com/viewtopic.php?t=22666
[2] http://www.msruns.com/viewtopic.php?p=145732
I have to support my locals though, Haltech and Link. They have a recent video on the Haltech YouTube channel of a tour of their facilities. It's no Toyota factory line, but feels very pragmatic and I love that they still do it in house.
Get yourself electronic ignition (Pertronix is a recommended brand) which replaces points and basically uses solid state electronics to fire the spark plugs, making them run much better and no more messing with points.
All engines need timing, but modern distributor-less motors do it automatically; timing should be a set it and forget it thing for the most part.
Then your carburetor is likely the issue for running rough, hard to start, etc. You could get a different more modern carburetor, but switching to fuel injection may be the way to go if you just want "turn the key and go". They make fuel injection systems that look and mount just like a carburetor but use more modern tech - look at FiTech, or Holley for solutions. Those are going to require you to add a sensor to the exhaust and a couple sensors around the motor (all included in the kit, but work to add), plus you'll probably need a new fuel pump that can put out much higher pressure (fuel injected cars use ~40-60psi fuel, carburetor is more like 3-5psi).
It stinks because it's burning raw fuel and you're not used to the smell of that thanks to today's cars with catalytic converters - they do sell them aftermarket that you could add in to your exhaust system as well.
At the end of the day, it's all very possible and there are open source projects like Megasquirt that could be a place to start, but going the open source route will be even MORE "fiddling around" than your current setup, so you may want to look at off-the-shelf EFI conversions. At least do yourself a favor and get Pertronix electronic ignition - it's a total game changer in terms of ease of starting, smoother running, and less hassle, and it doesn't cost much and is easy to do.
But for a digital solution, you're looking at an EFI conversion kit, with a ready made wiring harness to convert the necessary items to run the EFI. It is common enough to do that you'd have no trouble sourcing advice and if you like that kind of thing it would be a great project. I see Holley do good looking kits but I can't speak from experience sorry.
The difference between an ECU run V8 and an "analog" V8 is mostly in electronic control of ignition timing and fuel injection, and all the sensors needed for the ECU to know what's going on. I think just replacing the carb with an EFI carb kit would be a great project, but to take it further you would need to ditch the distributor and use coilpacks and ignitors controlled by the ECU, and a timing sensor to sense the position of the crank. At that point you need a full ECU and speeduino would do the trick, but there are supported manufactures of aftermarket ECUs as well like Haltech, Holley, Motec, and Link.
The MegaSquirt measures as its most basic inputs Manifold Absolute Pressure (MAP) and engine speed (RPM) and uses a Volumetric Efficiency (VE) [1] in a lookup table to calculate the fuel injection pulse width in order to combust at a stoichiometric air:fuel ratio (14.7g air:1g fuel) or maybe a bit rich (<14.7:1). A VE <100% is implied by all engines under vacuum because their displacement is constant while the atmosphere in the manifold is at a reduced density. Also good add an inexpensive intake air temperature sensor to adjust air density.
An oxygen sensor in the exhaust stream will "switch" between a lean signal —approximately 0.1 volts—and rich signal—approximately 0.9 volts. This acts as feedback to the engine management to add a correction to the theoretical VE.
More advanced is a "wide band O2" or "lambda" sensor that measures the air/fuel ratio over, as the name implies, a range of air/fuel ratios rather than just a nearly binary output at stoichiometry.
Many engine management systems use a Mass Airflow Sensor (MAF) to directly measure the mass of air taken into to the engine through a single point in the intake air piping and don't need to know much about the details of the VE of the engine.
Also I would say that controlling the ignition is very critical to a car.
> Also I would say that controlling the ignition is very critical to a car.
Indeed.
If something happens to the system that controls the ignition, it either runs poorly or stops altogether. No biggie.
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?
https://rusefi.com/ / https://github.com/rusefi/rusefi/wiki/Hardware
and others...
The engine feels like it’s running fast, but it’s really slow compared to ECU’s ability to observe it and respond to it. A single missed signal would just result in a misfire.
Like the notoriously hard to stall Citroën 2CVs and Dyanes, where roughly a third of the total weight of the engine was the ridiculous flywheel.
They could chirp the tyres in first, second, or third gear if you got all that mass spinning fast enough, not from power but from momentum.
If you're lucky ecu might crash or run rich in that one rpm/load point, if not it might run lean entire highway drive, if say a bitflip happens to flip lambda probe settings to always show mixture being too rich.
So no I imagine there's actually quite a lot of wiggle room to be off. Less so if you want it to last a million miles. But 30k?
There is a lot of protection in modern engine, like retarding timing when there is a knock or long/short fuel trims to correct for any changes in the sensors.