rotten egg smell though car comes up with no codes

[95se]

I have taken my car to two different mechanics and neither one can find anything wrong. About a year ago I had my '95se in for the 60K tuneup and the day after I got it back I noticed a rotten egg-hydrogen sulfide type of smell, noticable while driving with the driver's side window down. Don't have to be driving any particular way. The first mechanic checked it for codes and didn't get any. He asked if I topped off, which I had some. He said not to do that and give a while and see if the smell goes away, if not it needed a new cat converter. So the smell didn't go away and I just replaced the converter with a direct-fit bolt-on high flow cat a few weeks ago and the smell is still there. I took it to another mechanic today and he checked it out and the computer says everything is fine, all the voltages are right on the money, plus he said he couldn't smell it, neither could the other mechanic, which is funny because my Dad has disease sinuses and he could even smell it. The only thing I know to do now is take it to the dealership. Anyone have any ideas what I should do?? I wish I know of a good engine mechanic is the DFW area since I live in Arlington, tx.

[kid_nissan]

Everyonce in ahwile, i get the same thing i would like to know what that is also

[HippoSleek]

Generally, a rotten egg smell coming from your car is a sign of a bad cat. Since that has been replaced and you still have it, I don't really know what to say.

Any chance someone egged your car? Did you lose an egg under the seat? Sorry.

[gfisch]

Yeah, as you said, the catalytic converter is generally the problem when you get a smell like that.
Maybe the cat is getting to hot due to a faulty O2 sensor or sometyhing like that. I know you said that you got no error codes, but maybe still might be something to look into.

Also, arent there 2 cats? There is the primary one that is the downpipe from the exhaust manifold. Then, there is another part which I though was also a cat before the rear section of the exhaust where the resonator is.

Maybe you should just let the car run for a while, then try to sniff around under it to see where its coming from.

Good luck

[ForceFed97KA]

There are only 2 cats on California cars the one should be fake.


Originally posted by gfisch
.

Also, arent there 2 cats? There is the primary one that is the downpipe from the exhaust manifold. Then, there is another part which I though was also a cat before the rear section of the exhaust where the resonator is.

Maybe you should just let the car run for a while, then try to sniff around under it to see where its coming from.

Good luck

[HippoSleek]

I thought the second one was fake on the 95 cars only. The 96+ using two?

Greg - long time no see. Welcome.

[sykikchimp]

The sulphur smell from the exhaust, is actually caused by running the engine/cat convertor slightly lean for long periods and then running under a rich condition (ie going up a hill under heavy load) This is when the sulphur smell (rotten egg) is produced.

Under relatively lean conditions, the sulphur found in gasoline is converted to sulphur trioxide, then during the rich running condition the sulfur trioxide is converted into hydrogen sulphide (rotten egg smell) within the catalytic converter.


I would recommend running Different Gasoline, and maybe replacing/checking your O2 sensor.