Longer search terms . . .
Unfortunately, you cannot do a search on "ECA" using the search function, since searches require a term of four or more letters.
ECA, quite simply, is a stack of ephedrine, caffeine, and aspirin. It is used as a fat burner (the most common brand name is Xenedrine) - designed to help you lose or cut rather than bulk. It does have side effects that include raising blood pressure, heart rate, and glucose levels, so I do not recommend its use if you have any potentially complicating medical conditions.
You can find many forum posts on ECA. Using the search feature that Terinox described, do your search on "ephedrine and caffeine" (without the quotes. Most of the threads you will pull up will deal with ECA.
Additionally, in the A.R. Drug Profiles section, you can find a profile of ephedrine itself.