Mark (poisonkitty) wrote,

Hacking my car

It only makes sense that an open source developer such as myself would aspire to hack my car's computer. Alas, I've found the open source tools that allow me to do just such a thing. It did cost me about $97 for a high-dollar OBDII-to-USB cable (shipped) but this allows me to hook a computer up to the car's ECU (computer) and read and alter the data that it uses for various things (maps). There is a community of tuners willing to share their work with others and other tuners willing to share their secrets to anybody willing to participate (as well as providing software to edit your own ECU maps). It's pretty neat to see all of the values used to operate my car laid out in table format for me to tweak and change.

This evening, I uploaded one of the freely available maps to my car. Supposedly, it will increase performance as well as fuel economy as it makes a stronger assumption that this car will mainly be used in a 30-100 degree environment and use 91 octane fuel. This is a starting point for getting greater efficiency out of my car. I've been tracking my mpg fuel consumption, so I'm curious to see how this new map changes that. I can already tell that it performs better at slower speeds.

I'm going to setup a data logger once I get my ancient laptop back in working order. Anybody have a cheap 10-20 gig laptop hard drive? My laptop seems to eat drives about once a year or so.

For now, I'm content using somebody else's maps, but in order to feel safe about intelligently tweaking the values, I will need some safety gear such as an exhaust gas temperature (EGT) gauge, knock sensor and wideband O2 sensor. High exhaust gas temperatures are an indication that something has gone wrong. A knock sensor will let you know when the fuel mixture has been tweaked too far in one direction or another. The wideband O2 sensor is basically a much more sensitive version of the O2 sensor that the car comes with. The Subaru O2 sensor basically says if it's correct or not given the stock settings - it won't tell you what it actually is. I will also want a turbo boost gauge to measure performance. Some WRXes came with these from the dealership but mine did not.
Tags: ecu, wrx
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