Thanks for all the help so far. I got it working and recording data, displaying to the LCD and saving on the SD card.
Here is a quick video:
I have a few small issues. The first one is that the Arduino seems to randomly freeze while recording. The numbers on the screen freeze and no more data is recorded. I don't know if this is because it failed to receive a stream from the ECM and it just waits forever for the next one that isn't coming....or if I might be hitting the maximum RAM limit. How do I tell which one it might be?
The second issue is the speed of the program. When I was testing it to just show the data and not record or perform any big calculations, it was lightning fast. I added all this data logger stuff and a lot more functions now. I expected it to be slower, but not this slow. It seems to run at like 4 or 5Hz. Any ideas on how to speed this thing up? I suppose putting all of the logfile.print commands in a function maybe. I hadn't tried it because I was afraid it would cause problems, and didn't get time to experiment much.
I would post my code but it now exceeds the maximum length allowed in a message.
You can see my code on my project blog page here: Buell ECM to Arduino: Arduino Code R7 Datalogger Accel