A few years ago Sven and Juho started working on the same type of project without knowing about each other and only by a coincidence their paths crossed. They wrote me about their cool story and the successful experiment of upgrading a diesel engine using Arduino Mega:

There’s a prettty large community out there in the car/motorsports hobbyist world that loves their vehicle but the engine is getting old, worn out and maybe even too bad to renovate. What people do is to take the engine from a newer car with a modern direct injected diesel engine, with all the cables, sensors and motor controller (the ECU) and adapt it to their beloved old car. This is exactly what is going on with the VW buses (called vanagons in the US) where the diesel engines from the beginning is a bit on the small side and 20 years later their performance is not much better than a garden tractor. A “new” electronically controlled engine is used to replace the old worn out engine, and with that follows better power, less pollution and way better fuel economy.

BUT, this takes time and is a complex project. You have to adapt the cablage, install the ECU (the motor controller) and must be sure that all the peripheral sensors sitting all around the engine is brought over to the new car and is working. You might also have to adapt the instrument cluster behind the steering wheel to make all the warning lights and gauges to work again.

The idea with the Arduino controller is to take the ENGINE ONLY and then let the Arduino manage the engine with the sensors that is on the engine itself. By doing this, the motor swap is reduced to a weekend project and everything in the bus is working as it was before. No instruments modification, no need for external valves and sensors, no adapted cablage. Just the Arduino.

You can find the whole documentations and the details of the project on Juho’s website.