So I just recently restored my 90 535i that my uncle gave me, and it runs really great now but I have noticed that whenever I get out of the car after driving it, about 50% of the time there is the smell of sulfur coming from the tailpipe. I was thinking maybe it's the catalytic converter which if that's the case, I won't worry about too much as where I live we don't do emissions inspections; of course I'll get to it eventually, I just don't have the money right now after the cost of restoring the engine to its former glory. If it's running rich, I definitely want to fix that because that would of course eventually lead to the CC being burned out among other bad things. Anyways, I have asked a couple of friends IRL and they say it's likely because I'm running rich. I'm guessing it's because of my fuel pressure regulator, but I'm not entirely sure. Is there any way I can test it? It doesn't always smell like sulfur after a drive, I usually only smell it if I shut off the car before it completely warms up, which could also be why I'm running rich obviously. It's only been happening for a few days now, and I don't seem to be getting all that bad fuel economy. Not sure what good checking my plugs will do, as I'm guessing it takes a good amount of time before they foul from running rich. I have only put about 60 miles on the car so far since restoring it. Again, it's sort of random, but I noticed it happens if I turn off the car before the engine has completely warmed up (going a short distance). Anybody got any ideas? It runs great otherwise.