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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.

by Speeduino community

FULL CAD BOM FIRMWARE DOCS

AutomationOpen-hardware

Built withArduino

difficulty
●●●●●
time
a weekend-plus
license
GPL-2.0
repo
repo ACTIVE1,800 stars

WHAT YOU’LL NEED

Videos
1
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COMPAREE VERDICT

Speeduino is a mature open-source ECU with over 1,000 installations reported by the project. The firmware repository and the separate hardware repository contain what you need to build the board, flash the firmware and start tuning, and official resellers sell pre-made boards if you would rather not solder. The community is large, with Discord, a forum and a Facebook group. Budget for more than the board: a wideband oxygen sensor, an igniter if your engine needs one, and an engine-specific loom are part of a real install. The single biggest risk is not the hardware — it is the tuning. A bad fuel or timing map can destroy an engine, and you are responsible for understanding what you are changing. If you have never tuned an engine before, learn on a non-critical engine. If you have, and you want full control without paying 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 certification.

GOOD TO KNOW

  • —GPL-2.0 licence — open for commercial use.
  • —Firmware is in the speeduino/speeduino repository; PCB designs and BOMs are in the separate speeduino/Hardware 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.

Parts to buy

6 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • PCBFind
  • Arduino Mega 2560Find
  • Componentsfrom the repo files
  • Wideband oxygen sensorFind
  • Igniter moduleFind
  • Engine-specific loom and connectorsFind

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Can I build this?

Printnothing required
BuyPCB (from the speeduino/Hardware repo, or a pre-made board from an official reseller), Arduino Mega 2560, components per BOM, wideband oxygen sensor, igniter module, engine-specific loom and connectors
Toolssoldering iron, multimeter, laptop running Windows or Linux, TunerStudio software, basic automotive tools for installation
Skillsintermediate soldering, understanding of fuel injection and ignition timing, ability to read wiring diagrams, and willingness to learn engine tuning from scratch if you have not done it before
Timea weekend to build and bench-test the board, then another weekend minimum for installation and initial tuning — more if the engine has no documented base map
CostHigh budget, the board (self-built or from an official reseller) plus a wideband oxygen sensor, an igniter if needed, and the engine-specific loom and connectors
SafetyMains voltage if you use a bench power supply during testing. Petrol engines under power: a bad tune can cause backfires, overheating, or catastrophic engine damage. Lithium risk if you use a portable power source during mobile tuning. Do not tune on public roads.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

A builder (the_mintiest_micra) assembles and installs a Speeduino standalone ECU on a turbo Nissan Micra. Community video, not an official project video.

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Gallery

opengraph.githubassets.com

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the Speeduino wiki to confirm your engine is supported(The repository links to the wiki; start there before ordering anything)
  2. 2.Order the PCB using the files in the speeduino/Hardware repository, or buy a pre-made board from an official reseller(Most people use JLCPCB or PCBWay; minimum order is usually 5 boards)
  3. 3.Source components from the BOM and solder the board(Through-hole soldering; takes a few hours if you have done it before)
  4. 4.Flash the firmware with SpeedyLoader(The wiki recommends the SpeedyLoader utility, which downloads the firmware, the INI file and optionally a base tune; compiling in the Arduino IDE is only needed if you want to change the code.)
  5. 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. 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: you need a wideband oxygen sensor and controller to tune properly, and it is a separate purchase; buy a reputable one.
  • Not checking what TunerStudio edition you need — the free version handles basic tuning; the paid edition adds extra tools you may want later.
  • 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 of TunerStudio is enough to connect, configure and tune. The paid version adds convenience features such as automated tuning tools; check EFI Analytics' feature list before deciding.

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

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Discussion1

FROM THE COMPAREE TEAM

The ECU board is only part of the budget — sensors, wiring and tuning time add up. What engine would you run this on first?

CompareeTEAM2mo agoedited

Practical notes from our verification: the firmware repository is active (last push October 2026) and the project reports over 1,000 installations. The PCB designs are not in this repository — they live in the separate speeduino/Hardware repo — and the README points to official resellers if you would rather buy a pre-made board, which also funds development. Documentation is the online manual at wiki.speeduino.com, and it assumes you already understand engine management; support comes from the project's Discord, forum and Facebook group. Tuning is done in TunerStudio, a separate program from another vendor. Budget for more than the ECU itself: a wideband oxygen sensor for tuning and the wiring for your engine are part of a real install. The footage in our video is credited to the_mintiest_micra; the build-and-install video in our links is 'Building and Installing a Speeduino Standalone ECU - Turbo Micra Ep.2'. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Speeduino community

Speeduino began as an open-source, Arduino-based alternative to expensive commercial ECUs (its repository dates from 2013). It is now maintained by a community of contributors and reports over 1,000 installations.

GitHub

Star the project on GitHub

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.
GitHub repo