my exhaust smells like...rotten eggs

[stutt944]

what causes this? of course, its only evident under heavy loads, high revs. is it a cat converter thing? i have a '93 240sx se hatch with about 111K miles on it. she runs strong and i have no real complaints, except for the nasty rotten egg smell. the muffler/entire exhaust sounds about worn out, but that shouldnt be a smell thing, eh? anyways, any help would be great. maybe im just a dumb@$$. or maybe i forgot to take that casserole out from under the hood last wednesday on the way to bridge club...hmmm...

drewathens, ga

[sultan]

it's the cat, they smell when they're bad

[Phoenix1911]

I had an 355 cubic inch SB Chev in an old Malibu a couple years back. The engine combo put out about 400 ponies and with the Holley carb and racing cam she poured gas into the engine like a garden hose. Most of it would combust but some obviously didn't. Dual brand new racing cats on the exhaust and after running a 1/4 mile she would reek like rotten eggs. It may be a chemical reaction with the raw gas hitting the catalyst. When I used race fuel it was a differnt sweeter smelling rotten egg if you could imagine that?? What I'm saying is that your car may be running rich??? Not sure... Just food for thought

Phoenix1911

[stutt944]

thanks for the advice. i poked around some other places, and this seems to be the most obvious answer. the cat. what does a cat/pipes/muffler setup run, oem or otherwise. this is probably the most FAQ ever but what exhaust to go with. everyone probably has their favorite, but names like "b0mber" or "mad-rice-o-matic-2000" makes me wary of upgrading to these exhausts for fear of sounding like an high-revving kitchen appliance. so many people say their exhaust has a "good note" or "grumble" but c'mon...its 2.4 litres. how much grumble can you get?

thanks and please reply anybody.:wavey

[rschwalbe]

I would go with stock. From the Cat back you are looking at about $300 installed on a good day! And that is probably a low-ball figure at best! Shop around--that's your best bet.

[AVERAGE]

dont know about 300. it all depends on what type of muff u get. anything u put on that 240 is going to sound pretty damn good. and since ur at it , u might want to go with a high flow cat ......well , yeah with all thats been said . ur looking at about 3

[nisstek]

The rotten egg smell is sulpher in fuel. The sulpher is added to "winterize" the fuel. There's nothing wrong with the Cat. Switch to different brand of fuel and see if it improves.

[stutt944]

i never knew this. not the cat, huh? many other places/people i checked with all said it was the cat. converter... i use texaco 93 octane. always have. will the "winter-ized" variable decrease as we reenter summer months? im assuming so. please reply...thanks.

[nisstek]

We used to get this complaint alot, especially with Altima. After a couple Cats where changed, Nissan raised the BS flag and kicked back the warranty claims. I have also seen a NTSB that had us reprogram the ECM for the sulpher smell. But I cant remember which vehicle that was for, probably Maxima. If you have always used Texaco 93, try switching for a couple of tanks to another brand and see what happens. Want cost you anything.

[apzak]

I thought the rotten egg smell was my clutch? I noticed this smell whenever I tried to downshift (I'm learning and I double clutch/match revs). Anyways, I got hotshot headers and haven't smell this rotten egg smell yet so it might have been my cat. Weird thing is, it's a 98 with 40k miles, shouldn't cats last a lot longer? And if it was my cat, what does burnt clutch smell like?

[stutt944]

well, apzak, you may very well be right. my clutch was never in very good shape, and it WAS only during hard accel/load. and i just put a new exedy clutch in. i've only put about 50 miles on it since the replacement, and i havent been able to smell the sulpher since then. but then again, i've been babying the clutch lately. but in regards to these "fuel-related" replies, i did switch to another 93 octane since then, and i also replaced the fuel filter. this reminds me...how long am i supposed to baby the clutch? i also replaced my flywheel (90 for a new stock one is a lot more reasonable than 400 for a lightened one to me). i know the clutch is basically a giant brake pad and all, but for what lenght of time or distance do i go easy on it? anyone?

ps - the new clutch is funny. i've heard (and experienced) that pretty much all clutches act differently in one way or another. the pedal feel is really loose for about the top 60% of travel, and then only at the bottom (what feels like) inch or two of travel does the clutch engage/disengage. is this proper or normal? help i have so many questions!!

[stutt944]

OH, and i remember the car would make that smell when i was passing at high speeds. i would rev-match and downshift to 4th at 50 mph or so, and by the time i was around the car and back up into 5th, i would smell it then, too. also leads me to believe it may have been the clutch. it was one helluva spent clutch, too. it caused a mild heat fracture in the flywheel, which is why i replaced it as well.