Smelly (rotten-egg) Exhaust

COBESGT · Sep 21, 2008

Lately my car seems to have a really smelly (rotten-egg) exhaust smell and the power doesn't seem to totally be there. Is this normal? I never noticed this before.

Here is what I have:
1. 22000 miles
2. JLT II CAI, Brenspeed 87 Octane tune installed, Underdrive Pulleys, and Flowmaster Exhaust.

Here is what I've done:
1. Just replaced the Fuel Filter (power seems better but still smells occasionally)
2. Returned car back to stock-tune, then re-loaded 87 Octane Tune.
3. Checked for codes and had none.

I know (at least I think I do) that rotten egg smell comes from the exhaust temp not getting hot enough to burn it off inside the cats. Just wanted to post the question to see if this normal or leading up to some sort of problem.

THANKS

dro · Sep 21, 2008

Sulfur in the gasoline. It might be your area or brand of gas you buy. Did you try switching to a different brand/area where you buy your gas?

Khyron · Sep 21, 2008

A rotten egg smell from the exaust usually means a catalytic converter is going bad.

firestang70 · Sep 21, 2008

Khyron said:
A rotten egg smell from the exaust usually means a catalytic converter is going bad.

+1 bad converters. You should be able to find a stock catted midpipe on a forum for cheap. Good luck.

COBESGT · Sep 21, 2008

dro said:
Sulfur in the gasoline. It might be your area or brand of gas you buy. Did you try switching to a different brand/area where you buy your gas?

I too think it's probably some bad gas. I've really tried to stick to the big companies when I fill-up, but occasionally other small shops are more convenient when in a hurry. I'll give it a try to see what the outcome is. Hopefully it's the gas and not a bad cat. I find it hard to believe a cat could be going bad already, only after 22K Miles.

NastyStang113 · Sep 21, 2008

It's possible.

dro · Sep 21, 2008

COBESGT said:
I too think it's probably some bad gas. I've really tried to stick to the big companies when I fill-up, but occasionally other small shops are more convenient when in a hurry. I'll give it a try to see what the outcome is. Hopefully it's the gas and not a bad cat. I find it hard to believe a cat could be going bad already, only after 22K Miles.

Yea, i highly doubt it. And you're not running gobs of power that would foul out your cats so its not a HP issue.

NastyStang113 · Sep 21, 2008

dro said:
Yea, i highly doubt it. And you're not running gobs of power that would foul out your cats so its not a HP issue.

I don't. It happens more often than you'd think. I had a 2004 F150 that had bad cats with only 15,000 miles. Same deal ...

STANGmole · Sep 22, 2008

FWIW, my '08 GT has under 900 miles on it and it's exhaust smells like rotten eggs...

If the cats aren't functioning shouldn't you have an engine code or something?

I just don't see Ford replacing them under warranty if the only issue is that they reek like sulfur...has anyone else had any experience with this problem?

mustangdave · Sep 22, 2008

Just thought I would throw this out: an overcharging battery smells exactly like rotten eggs. Are u sure it is ur exhaust?

NastyStang113 · Sep 22, 2008

STANGmole said:
I just don't see Ford replacing them under warranty if the only issue is that they reek like sulfur...has anyone else had any experience with this problem?

Like I said, I had a 2004 F150 that had the cats replaced because of this. I just noticed today my exhaust is starting to smell a little like sulfur. It's not too bad but it's not good, either.

blbrchnk · Sep 22, 2008

NastyStang113 said:
Like I said, I had a 2004 F150 that had the cats replaced because of this. I just noticed today my exhaust is starting to smell a little like sulfur. It's not too bad but it's not good, either.

Mine too, of course I don't have cats so maybe that is my problem.

69mach1-409 · Sep 22, 2008

Not saying this is it but, I've heard of a bad tune killing your cats. Maybe you should get your AF's checked?

NastyStang113 · Sep 22, 2008

My A/F are spot on and they were on my 2004 as well. This might be a reason to get a offroad pipe ...

lexluthr69 · Sep 22, 2008

I have very similar aftermarket components, although I'm running Bama 89 tune and stock exhaust and I had an incident that put my cats into question as well.

About 2 weeks ago I was coming back from a ~50 mile trip and for about 15 miles of that I was doing about 95-100mph and suddenly there was a noticeable "bump" and then I had to really get on the accelerator to have any power. It felt as if I had dropped a cylinder or two. I nursed it home, fearing for the life of my car. Once home, I wanted to grab my scanner while the lil' wrench light (CEL) was on and see what it would tell me, but my house key was on the same ring as my car key, so I shut it off. Then I figured why not see how it'll do once I start it back up. So I did, and it started up just fine, as if nothing untoward had happened. I turned it off, grabbed my scanner and no codes at all. No stored codes... nothing.

I figured I'd check the smell of the exhaust for any tell-tell signs of problems, thinking maybe the codes had been cleared through some sort of electrical miscue and weren't reading out properly. The exhaust had an immediately noticeable, albeit faint, smell of sulfur.

My first thought was bad cats, but I'm also at ~23k miles and now after reading this, I'm wondering if it's just somewhat normal for our cats to peak early on random cars.... or maybe I do indeed have bad cats. Hmmmm.......

Grabber07GT · Sep 25, 2008

As I'm sure you know, a catalytic converter's sole purpose is to turn bad chemicals into less-bad chemicals. Sulfur is a big one as it bonds to oxygen and hydrogen and causes acid rain. I think cats are rated for 10 yrs. I'm not sure but I think that's an EPA requirement. Given that it's only been 3 yrs (~20k miles) and their purpose is to catalytically convert the sulfur containing compounds (and others) into less reactive compounds and there's already an odor of sulfur, why wouldn't the cats be replaced under warranty, assuming that they are indeed bad? I agree that it could be sour gas (high sulfur content), but I think that's regulated pretty well. Also, even some of the mom & pop stations buy their gas from the big name refining companies. There just aren't too many companies that make gasoline. You can see the sticker sometimes on the pump ("We sell Exxon gasoline") I'd start with the cats, personally. That's just me. Good luck birddogging the problem.

GOLDENPONY · Sep 28, 2008

Rotten egg smell

Usually from the cats. They used to sell some stuff in a bottle, catalitic converter cleaner - you just put it in the tank like injector cleaner. Haven't looked for it for a while, you might check like Pep Boys, Auto Zone, etc.

Gregor111 · Sep 29, 2008

Grabber07GT said:
As I'm sure you know, a catalytic converter's sole purpose is to turn bad chemicals into less-bad chemicals. Sulfur is a big one as it bonds to oxygen and hydrogen and causes acid rain. I think cats are rated for 10 yrs. I'm not sure but I think that's an EPA requirement. Given that it's only been 3 yrs (~20k miles) and their purpose is to catalytically convert the sulfur containing compounds (and others) into less reactive compounds and there's already an odor of sulfur, why wouldn't the cats be replaced under warranty, assuming that they are indeed bad? I agree that it could be sour gas (high sulfur content), but I think that's regulated pretty well. Also, even some of the mom & pop stations buy their gas from the big name refining companies. There just aren't too many companies that make gasoline. You can see the sticker sometimes on the pump ("We sell Exxon gasoline") I'd start with the cats, personally. That's just me. Good luck birddogging the problem.

I think Grabber hit it. Your Cats should be covered for ten years as I believe federal law mandates that automakers warranty the emissions equipment for that time period.

Greg

stang8urimport · Oct 2, 2008

EPA requires manufacturers to warranty any emissions equiptment for 8 years/80,000 miles.

Smelly (rotten-egg) Exhaust

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