I've watched a few of this guy (ScannerDanner) videos over the years and they are very good! He's an instructor, not a back yard mechanic. So I thought I'd start a thread with some of the YouTube Videos that are pertinent to GM EFI systems and will add to them.

Start off with GM Ignition ByPass system, one of the best explanations I have seen. Although this one is for a V6 DIS system it's information also falls back to TBI systems as well.