Which injector is 1:
I was thinking I knew the correct order of my injectors, but then I realized the harness on an '04 avalanche runs to the engine from the front, not from the rear, so that would mean that the injector wire furthest away from the fusebox would be #7 (on the driver side). I've seen some harnesses labeled, but I'm not sure if these are truck harnesses or not and for all I know an LS1 harness may be backwards.
UnderHood FuseBox ---------------------------------I--------------------I---------------I--------------------I
#1 #2 #3 #4
If this is the case, I've been thinking of it backwards.









