I do remember reading about the ECM being able to change the ignition timing too, but for the life of me I could never figure out how. So earlier this week I got in touch with a friend from college that shared the same electrical engineering classes as me. He currently works at Wells Electronics, so I asked him if he could look up some info on the Wells part # 6H1187 (The N/A ICM).
What I found out is that the green/yellow wire that goes to the ICM (the small plug with only one wire) is not an enable/disable. Instead when power is applied it activates the pick-up unit connected to the ICM and shifts the ICM’s pick-up point, which causes the base timing to advance 2 degrees. The ECM only does this when the barometric sensor reads low ( car’s 1000m above sea level or perhaps drove into a tornado..lol).
The N/A’s timing during regular operation is still all mechanical.
I agree that having a gear puller to remove the armature would have been ideal, but I was stuck in a Shopko parking lot 80 miles from home when my ICM failed. I was able to get the armature off with a screwdriver, but I destroyed the pick-up unit in the progress. I figured $20 for a pick-up unit was a lot cheaper and faster than an 80 mile tow...
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The lesson I learned from that was don’t install a MSD Blaster coil and try to drive it off the stock ICM. I found out just 4 days after installation that the power requirements for it overloaded my ICM and burned it out.
