The automotive industry’s switch from carburetion to fuel injection was one of the most effective advancements of the 20th century. Electronic fuel injection allows for precise control over an internal combustion engine’s air-fuel mixture, which dramatically improves fuel efficiency and performance. But that requires computer oversight, which is why Kenyan engineer Peter Mbiria developed his own Arduino-based custom engine control unit (ECU) for upgrading vintage cars.

Electronic fuel injection conversions — from either carburation or mechanical fuel injection — aren’t very common, because they require computer control and that has to be tailored to the specific engine. With the exception of a few very popular models that warrant turnkey solutions, it simply isn’t worth upgrading most engines. But Mbiria’s custom ECU makes the process much easier, to the point where it can be worthwhile to convert older engines. The conversion gives them new life, increasing economy and power.

Mbiria’s Voltarent ECU can work with four-cylinder, six-cylinder, and eight-cylinder engines. After the conversion, it controls the injectors and ignition. A small OLED screen, mounted by the car’s dash, displays information and the driver can switch modes (economy, comfort, sport) using a knob. 

Those modes, and the injector control in general, are only possible because of sophisticated algorithms running on the firmware that Mbiria developed himself. He chose to use an Arduino Due board to take advantage of the many I/O pins, but also for the processing power of the AT91SAM3X8E microcontroller that is necessary to perform the calculations fast enough to keep up with the engine. Mbiria designed a custom PCB to host the Arduino and provide an interface to the injectors, ignition system, and user interface. And with relatively simple tweaks to the Arduino sketch, Mbiria can make the ECU’s firmware suitable for whatever car he’s working on.