I recently installed a Streetfire ignition box (made by MSD and same setup instructions) on my 88 grand Wagoneer. Per the instructions I attached the small red wire to the wire that went to the positive on the coil. This wire gets power from the starter relay. When I start the engine it runs. When I turn off the ignition and put the keys on the dash it keeps running.
I read through forums for awhile and read that the MSD/ Streetfire box should not be connected to the starter relay. Whew! Long story short! What specific switched 12v source have others with an MSD ignition box tied into. I'm terrible with electrical systems!!! A coloring book option describing what 12v you used might be necessary! Ha ha! Ooh! I also have the TFI upgrade.