My 1987 560SL failed NJ emissions. In throes of overkill I replaced all of the injectors and the O2 sensor. It ran well, but stumbled slightly on acceleration and blew black smoke. Gas mileage was poor. I took it to an independent shop and had them put it on an emissions analyzer and adjust the mixture control It will now meet NJ standards for idle, but as soon as you run it at higher rpm's, it still spikes way over the limit. I'm trying a second indie shop tomorrow, but hold out little hope. I've just made an appointment next week at the dealer, and they are already rubbing their hands together and cackling.
Has anyone had this particular problem before? The archives and DIY are full of information on how to test the individual components, but the information is not symptom-based. Any ideas would be appreciated.
1986 560SEC: 150,000 miles, runs great, but I've got to sell it (too many cars for one man)
1987 560SL: 122,000 miles, used to run poorly, now (thanks to forum), runs great!
1997 GMC Jimmy: Turned out to be a turkey.
1989 T-Bird Super Coupe: 150,000 miles, still runs great. Ford got it right.