Working on an 85 Z w/ TPI. In the process of changing out the computer I pulled the PROM out and the plastic holder around it broke. Well, then I couldn't tell which way it needed to go when I put it back in (the plastic holder will only snap in one way but the PROM itself is symetrical and relys on the plastic piece for direction). I just took a guess and put it back in. Well the car idled like crap. It hunted for idle before but, I don't think it was anywhere near that bad (its not my car so I don't much about how it used to run). So then I removed the PROM and tried the other way. No change. Then I just took the PROM out to see what would happen. The car ran about the same. Did I fry the PROM? I read much later somewhere that the PROM had to go back in the same way it came out. Is that true? And if the car ran without the PROM, what exactly does it do?

 

The PROM is junk.

The notch in the end of the prom matches with the end of the holder with the notch.