I was mostly being sarcastic - no offense taken. I know all too well what you mean about being stranded on the side of the road in south central Missouri. If this is going on your daily driver you'd be best served by not even removing any of that "legacy" hardware for a few years until we know how this will handle real world conditions. I don't know how much room there is on a b-body but on the y-body I'd rather pull the engine out than to try routing plug wires without removing the left wheel, inner fender and most of the belt driven accessories. And forget about attempting it the side of the road.

It should have occurred to me to try a trim pot Sunday when I was working on the comparator because the project I borrowed the potentiometer from was itself a voltage sense / comparator circuit. Was too busy looking for an "easy" solution and not thinking systematically. I probably spent the better part of an hour digging through parts totes looking for my original (failed) ignition module to hack open in hopes of finding something useful.

Quote Originally Posted by lionelhutz View Post
I'd think the ignition module more or less has the base of the coil driving transistor connected to that pin.
I initially thought that myself but there's definitely more to it than that because the module only switches on / sources current through the coil when the EST line is turned off and allowed to float. So minimally there's an inverting input stage there.

Fingers crossed I hope to finalize the initial circuit design tonight. Once I'm happy that it's doing more or less what it should be doing I'll try to finish the schematic. After that I probably won't be very active on the project until I get the engine out / back in.