1993Geo 4AFE in my 1990 cellica st?

I just bought a 1990 cellica st in very nice condition. The seller told me he swapped engins but everything bolted up fine. What I did not realize was the electronics do not match up as well. I am getting black smoke out my exsaust and am thinking the wiring and electric components are sending a bad fuel mix. I am no mechanic but I am very mechanicaly inclined but this is over my head. I have tryed messing w timing and tune up but I need to know if I need to buy a new computer or if it is possible to make this work. The engin runs fine just black smoke. any help is appreciated! the new engine is from a 1993 geo 1.6 4AFE. He told me the old engine was a 4AFE also but I am not sure he was kind of a hack.

should be the same, I mean the Prizm is just a Corolla with a GEO badge, but I'd go into a JY and look around for a celica and check to see if everything check out.