My sisters 1992 Jetta failed smog because it idles at 1400 rpm, and the max allowed is 1200. Its a digifant I RV code 8v. I would not be surprised if this was caused by me doing something wrong when i worked on it, but im not sure what exactly it might be. I do know I did a couple things wrong, but I dont know if they would still be an issue.
If you dont want to read all the details, basically I swapped a rebuilt head onto the car because the valve guides were completely shot in the old one, and now it idles too high.
It was purchased with ~90k miles, and it seemed to run ok when we bought it, but we discovered later it would smoke heavily when cold and used about a quart of oil per tank of gas. I found a rebuilt head on vw vortex with a TT 268 cam and bought that and put it on. While doing this I made a couple of mistakes:
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I accidentally broke the plastic throttle cable attachment on the throttle body, so I had to replace it with another used one.
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Since the european parts specialist at autohausaz does not acknowledge that there is a difference between CIS and digifant intake manifolds, the intake gasket i was sent was for a CIS car, and rather than ordering a new one I bought a felpro one at napa auto parts which is very very badly made.
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While the car was disassembled for the job, the distributor was used in another car as a test of diagnostic purposes, and no longer functioned when reinstalled in the jetta. The only replacement I could find at the time had a slightly damaged shafe to the rotor didnt seat properly, which ended up causing almost $1k in damage to the car.
When i got the car back together and running, it idled at about 3k rpm, so I adjusted the idle to the proper speed with the screw on the throttle body using vagcom to get it within the right range, then after driving for 2 30 minute trips, the idle speed dropped too low, so i reset it again, and most of the time it was fine, but sometimes it would idle at 1400 unless you load the engine with the clutch a little then it would drop down and idle normally.
The damaged distributor eventually caused the coil to start to fail, which ended up ruining the cat, oxygen sensor, melted the oxygen sensor wiring, anda few other things. After it was all fixed the car seemed to run normally again though.
Any ideas of what could have happened? I really hate these cars, they are so complicated, and there is really almost no knowledge about them. They have almost all been scrapped here becasue people dont want to put the money into keeping them running, and the people who do are more the "yo dawg, swap in a VR' types.
