Fuel trims video
 

I've learned a few things like AFR, ignition timing and maps and cells, but I wasn't quite sure what fuel trims do. Here's a pretty good explanation with live demo. The interaction between short and long term trim is interesting.. now I'm going to go back and look at my logs and see if I can make sense out of them :)

[ame]http://youtu.be/oRX2V6_a3dc[/ame]

In general, there are some really good explanations of things and of course tuners helping out here even if not their customers.

Great find!