I was doing some work on the Arduino part of the project today. It seems that the intake, trans, oil and engine bay temperatures all fail after about 5 minutes of running. These are all DS18B2 sensors that run on a one-wire bus - so the problem is finding out whether there is a bad sensor, bad connection or a problem with the Arduino itself. Preliminary troubleshooting says it's the trans sensor that is flakey.
While I was out there I thought it would be fun to see if I could get a screen capture of the system in operation - even though the above referenced temps are not showing accurately. So I did a search and found an app that looked like it would work.
Here is a quick YouTube video showing the Gauges program in operation. A couple of things to keep in mind - first the three temps that are showing are not connected to the right gauge, second the screen capture program is forcing the Gauges program to restart when switching between apps - this does not normally happen and finally the capture program is working at 8fps so it is a little jerky and its resolution is 1/4 of the screen resolution so it appears quite pixelated compared to the actual and since I'm testing the free version it has a watermark on it.
But should provide a pretty good idea of how it works.
http://youtu.be/99d51kPf7qU