The previous 2 posts were just theory, but today I borrowed an oscilloscope and looked at my injectors. When I looked at the voltage across the shunt (.27 Ohms), I saw this:
(something like this)
The A section seems to be the "peak" and the B section seems to be the "hold" and also the "pulse width" that I care about. I watched the waveform, and when I turned on the A/C, the "B" section extended a bit. There ya go.
Could anyone offer me their expertise in how to trim/condition that signal?