The stock engine management system is made up of two modules, an ECU (engine control unit) and a knock sensor unit. I wanted to get a better understanding of how they work, but couldn't find much information to start with. Perhaps my google-fu is not powerful enough, but there doesn't appear to be any publicly available information on the modules themselves. All i can figure is that the knock sensor was created by Mitsubishi, and the ECU by Denso.
Lets crack them open!
I started with the knock controller. Engine knock is an event that occurs in an engine cylinder where ignition occurs too early and/or in multiple locations causing turbulence which can knock the piston into the side of the cylinder wall instead of pushing it smoothly straight down.
Wikipedia: http://en.wikipedia.org/wiki/Engine_knocking. Sensing engine knock is a complex process which starts with taking audio input from a microphone or piezo sensor mounted on the engine and then isolating a specific sound frequency.
I was surprised by what I found, which was.. not much
The datasheet for the 2 ICs show that they're quad comparators. I expected to see a microcontroller or DSP! Underneath I found another PCB connected by a ribbon cable.
Not very interesting, so I decided to move onto the ECU.
http://forum.clubna-t.com/showthread.php?p=42205 I found that at least a few people have successfully hacked them.
"I hacked the Denso MCU a long time ago.
The above board runs the original factory code that is inside the original ECU.
If I leave the code stock (apart from a couple of essential byte changes to swap the mode and ensure the ROM checksum is OK) then the ECU runs exactly as stock.
It's possible to alter anything in the original program or the mapping."
So it seems that some clever people are able to do some interesting things with it, but that's beyond my capabilities. I at least got to learn a couple of things, which was really the whole point.