Hey so I just bought a 1980 928 manual. The previous owner was just about bankrupt by the time he sold it to me so some mantanence had been neglected. Anyway right after I got it home it went up on jack stands so I could se what I had just bought and do some repairs. Wilst poking about I noticed the wire to the the oxygen sensor was damaged and dangling freely. Well after about two weeks I lowered the car back to the ground, reconnected the battery and tried to start the car. After about five or six tries it finally sputtered to life and idled a bit rough. I drove it for about five minutes to get it warmed up, then parked it and the rough idle resumed.
I would really appreciate advice. Can I expect a normal idle and easy starting after I fix the oxygen sensor wire or are they unrelated issues?

 

How was it running before you put it up on stands?
is it an US car with L jet?
Could it be fuel (pressures) or timing issues (cam gear, distributor, etc)?
Did fixing the o2 sensor make the computer run amok? (Not sure if L jet has a computer for oxygen sensor?)

sorry couldn’t help more