93 z28 no spark from opti to plugs but 12v at coil 9v at cranking plz help I've been through multiple check lists on here an everything checks out jus replaced opti its 3rd one this year jus purchased the car few weeks ago started there once I found no spark at plugs. Getting 4v on high low 12v on feed signal wire check out. Opti check harness isnt backwards. Plz help lol

 

have you flashed for codes yet. try that and see if anything comes up. I would pick up a ignition control module and try that if you haven't already. when I had one coil setup I carried an extra in my glovebox.