it should be the black. if you run the car with it all plugged in you should see that when the plug fires that wire will lose voltage. thats the primary coil. the other two should actually do basically the same which makes it kind of confusing. the other two will be grounded to fire the plugs. if you were to hook it up to one of the others i dont think those 2 cylinders would be firing.

im confusing myself here. im pretty sure you need the black wire though. i wish someone would help me out here.

yeah I wish I knew which wire it was on the SR20, but I dont know about any schematics for that engine. But I'm going to get it straightened out with Sun Auto today. Once I have it down for sure, I'll start testing different hyunda engines with the HFS.