OPEN-SOURCE ECU REPLACES YOUR CAR'S FACTORY BRAIN — YOU TUNE IT FROM A LAPTOP
An Arduino-based board that replaces your factory ECU and lets you tune fuel injection and ignition timing from a laptop.
AutomationOpen-hardware
- difficulty
- ●●●●●
- time
- a weekend-plus
- license
- GPL-2.0
- repo
- repo ACTIVE1,757 stars
●●●●● · a weekend-plus · GPL-2.0 · 1,757 stars · repo ACTIVE
WHAT YOU’LL NEED
- 3D printer + filament — printable parts — files are in the repo
- Electronic parts — full list with part numbers in the repo BOM
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
Speeduino is a mature open-source ECU that has been running real engines since 2014. The repository contains everything you need to build the board, flash the firmware, and start tuning. The community is large — over 1,700 stars, active forums, and documented support for dozens of engine types. The board itself costs around 160 dollars if you order the PCB and solder it yourself, but a realistic running setup with a wideband sensor, an igniter, and an engine-specific loom will cost you 350 to 500 dollars. The single biggest risk is not the hardware — it is the tuning. A bad fuel or timing map will destroy pistons, and you are responsible for understanding what you are changing. If you have never tuned an engine before, this is not the project to learn on. If you have, and you want full control over your engine without paying thousands for a commercial ECU, Speeduino is exactly that. One more thing: emissions and roadworthiness laws apply. In many places, swapping the ECU makes the car illegal for road use or requires engineering certification. Check before you build.
IN THE REPO
NOT IN THE REPO
- —GPL-2.0 licence — open for commercial use.
- —PCB Gerbers, BOM, and firmware are all in the repository.
- —Documentation covers wiring, installation, and base tuning, but assumes you understand engine management.
- —TunerStudio (the tuning software) is free for basic use; advanced features require a paid licence.
- —Does not include the wideband oxygen sensor, igniter, or engine-specific loom — those are separate purchases.
- —Roadworthiness and emissions laws vary; using an aftermarket ECU may be illegal or require certification where you live.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Partner · KickstarterHeyGears G1: 10M+ colors and transparent parts in one print, plus UV printing on flat objects. Figures, parts and labels — no painting.
Videos
Video from the payload, content not verified
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the Speeduino wiki to confirm your engine is supported(The repository links to the wiki; start there before ordering anything)
- 2.Order the PCB using the Gerber files in the repository(Most people use JLCPCB or PCBWay; minimum order is usually 5 boards)
- 3.Source components from the BOM and solder the board(Through-hole soldering; takes a few hours if you have done it before)
- 4.Flash the firmware using the Arduino IDE(Instructions are in the repository; you will need a USB cable and the correct COM port setting)
- 5.Bench-test the board with a multimeter before connecting it to the engine(Verify voltage levels and injector outputs; this step catches most build mistakes)
- 6.Install the board, connect the loom, and load a base map in TunerStudio(The first start is the moment everything can go wrong; have a fire extinguisher nearby and do not run it under load until you have confirmed fuel and spark)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- Buying the board without checking if your engine is supported — not every engine has a base map, and some need custom trigger patterns you will have to configure yourself.
- Underestimating the wideband sensor cost — a decent one is 100-150 USD, and the cheap ones lie.
- Assuming the free version of TunerStudio is enough — it works for basic tuning, but if you want real-time logging or advanced features you will need the paid version.
- Not understanding what a fuel or timing map does before you start changing numbers — the wrong value in one cell can hole a piston in seconds.
- Installing it on a road car in a jurisdiction where aftermarket ECUs are illegal or require engineering sign-off — the fine is usually more than the entire project cost.
- Skipping the bench test and connecting the board straight to the engine — if you wired the igniter backwards, you will know when the coil pack explodes.
Do I need to know how to tune an engine before I start?
Not strictly, but you need to be willing to learn, and you need to understand that mistakes destroy engines. The Speeduino community is helpful, but they will not tune your car for you. If you have never touched a fuel map before, budget time for reading and expect to make mistakes on a non-critical engine first.
Can I use this on a road car?
Depends entirely on where you live. In many countries, replacing the factory ECU makes the car illegal for road use, or requires engineering certification and emissions re-testing. Check your local rules before you install it.
Is the paid version of TunerStudio required?
No, the free version works for basic tuning. The paid version adds real-time data logging, advanced diagnostics, and a few other features. Most people start with the free version and upgrade later.
How do I know if my engine is supported?
The Speeduino wiki lists supported engines and trigger patterns. If your engine is not listed, you can still use Speeduino, but you will need to configure the trigger settings yourself — that requires an oscilloscope and a good understanding of how crank and cam sensors work.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
The board itself is about 160 dollars, but a realistic running setup with a wideband sensor, igniter, and loom lands closer to 350-500. What engine would you run this on first?
Speeduino community
Speeduino started in 2014 as an open-source alternative to expensive commercial ECUs. It is now maintained by a community of engine tuners and runs on everything from motorbikes to V8s.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM21d ago
Practical notes from our verification: the repository is active — last push was 28 July 2026 — and the community is large, with over 1,700 stars and documented support for dozens of engine types. The Gerber files, BOM, and firmware are all present, and the documentation is detailed, though it assumes you already understand engine management. TunerStudio is free for basic use, but the advanced features (real-time logging, diagnostics) require a paid licence, and that is not stated up front in the repository README. The single biggest cost is not the board — it is the wideband oxygen sensor and igniter module, which together can run 200-250 USD depending on what you buy. The reel footage is credited to the_mintiest_micra; we do not have a direct source link for those clips.