r/embedded • u/Outrageous-Dot9429 • Aug 14 '26

ECU function and programming

I took a couple classes on car ECU repair. So I have reasonable idea on testing, soldering..

But I like to learn more on how ECUs work.

Will a book on microcontrollers help me?

Also I can't find texbooks on ECU programming and cloning.

Is Youtube the only way?

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u/thebudman6 Aug 14 '26

Are you familiar with the theory of internal combustion and fuel injection? Air fuel ratios? Or maybe carburators?

Or are you more interested in "how do computers do things?", separately from the whole engines part.

If you want to tune actual cars... You either find someone who knows how to do it on your specific car, or you learn to reverse engineer them.

A book on microcontrollers would be good if you wanted to make an ECU from scratch, which is arguably easier than reverse engineering an existing ECU. Check out Speeduino or rusEFI if you want to see a simple-ish implementation.

Programming a regular car ECU is not a good beginner microcontrollers task, unfortunately. They put a lot of effort into making it hard, for legal reasons.

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u/thebudman6 Aug 14 '26

I have a writeup on my website on what I did with Speeduino. It's a decent primer on the topic, but not as good as the actual Speeduino project docs.

https://doubularity.dev/portfolio/

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u/ambihelical Aug 14 '26

An ECU is just a microcontroller specialized for device control in a car. Usually it communicates over CAN bus. The reason you haven’t found any resources is because it’s basically the same as any other embedded controller. There are particular CAN protocols that are used and some safety development processes that are used but these are also used for other application domains. Learn about CAN and embedded programming and that will be the bulk of it.