rotten egg odor?
 

OK...6 months ago my check engine light came on in my 1993 300E. After checking things out, and con\sidering it had just hit 80,000 miles, I replaced the oxygen sensor and reset the light. It stayed off fo 2 months and then came back on. Mileage has stayed at a constant 26-28mpg and it runs great. Today my wife mentioned that the car had a heavy duty rotten egg odor under hard pulls like accelerating up hills. Catalytic convertor? Any thoughts?

It does sound like Catalyst Converter.

yep, thats the smell you get if you run with no cat, my bet is that it needs to be replaced.

The smell is definitely being caused by the catalytic converter but that doesn't mean it's bad. It could be reacting to fuel with higher than normal sulfur content. I used to hear this complaint quite often in the early nineties. You say the car runs good, with no loss of fuel economy or power. That eliminates a clogged cat. If the car will pass an exhaust emissions test I'd forget about the cat, unless of course the odor is unbearable. You might try changing the brand of fuel you're using to see if there's any change.

ILuVMILS

I am with you on that theory 100 %.
Smelly cats are usually high sulphur fuel, ignition misfires, or too much fuel.
Since his mpg is so good, your suggestion sounds right on the money.;)

It's fairly normal for this to happen on a catalyst car, but did anyone notice how Volvo's seem to do it pretty badly?