Can a CAT "clean" itself?

[Popinski]

Last week, I put the HVAC vents on "Fresh" mode and noticed a rotten egg smell. I popped the hood and the rotten egg smell was very noticeable around the CAT. I drove around like that for a week and researched junk yards and other websites to find a cheap CAT. As of yesterday, the smell stopped. I even put my nose 2 inches from the CAT and no smell was present.

Is there anyway the CAT can unclog itself or something? CAT's are so expensive!!!!!!!!!!!!!

NOTE: Check engine light is NOT on.

Question 2: Are there any fuel additives that will help unclog a cat?

 

[Pablo]

If a catalyst is spent, broken or highly clogged, no. But the very definition of a catalyst is self cleaning. It's possible you had some groad in the catalyst and it eventually oxidized and went bye-bye.

 

[Boomer]

This can be very fuel sensitive. Did you fill the tank during the odor with fresh fuel?

 

[Tegger]

Originally Posted By: Popinski
Last week, I put the HVAC vents on "Fresh" mode and noticed a rotten egg smell. I popped the hood and the rotten egg smell was very noticeable around the CAT. I drove around like that for a week and researched junk yards and other websites to find a cheap CAT. As of yesterday, the smell stopped. I even put my nose 2 inches from the CAT and no smell was present.

Is there anyway the CAT can unclog itself or something? CAT's are so expensive!!!!!!!!!!!!!

NOTE: Check engine light is NOT on.

Question 2: Are there any fuel additives that will help unclog a cat?

What make, model, year and mileage? What makes you think the catalytic converter is "clogged"?

That rotten-egg smell is hydrogen sulfide, a byproduct of cat operation when sulfur is present in the fuel in large enough amounts. Gasoline has varying amounts of sulfur in it, so you'll get varying amounts of rotten-egg smell from fillup to fillup (usually no smell, or only on heavy acceleration).

There's not a thing wrong with your cat, so don't even _think_ about replacing it on account of a rotten-egg smell!

 

[mikered30]

Is this a toyota?

 

[eljefino]

Heard a rumor of Ohio not really monitoring retail gasoline for quality.

 

[MarioT]

Cat smelling around it, and not via the tailpipe?

I once had that symptom and it was only a plastic bag (caught on the road) slowly melting on it. Removing the leftover and letting burn the rest a few days "cure" it.

Unless you got a leak around the cat, there's no way a bad/plugged cat would smell I think.

 

[cchase]

Several weeks ago our 2006 truck had this problem. It was quite unnerving and seemed to go away with the next tank of gas. I can only imagine what is going on with fuel blends.

 

[someguy]

I also don't think it would smell under the hood unless there is an exhaust leak. Ive heard stories of a cat gutting itself, but aftermarket header was installed.

 

[lexus114]

Originally Posted By: mikered30
Is this a toyota?



I know right? They seem to be the real smellers out their, especially on regular grade fuel for some reason.

 

[dwendt44]

I would think a good long run on the highway would get things hot enough to clean any small pockets of contamination even if that's what you have there. But as had been said, CAT stink comes form the tail pipe.

 

[mechtech2]

Smelling the cat is useless.
It vents through the exhaust pipe, not it's sides.

They can stink when cold - not up to temp yet, but be perfectly fine.

Can they clean themselves? Only from fuel or oil that would be corrected in a few minutes. Deposits are another thing - they can be coral hard and tough.

 

[Popinski]

Thank you guys for the replies. The gasoline that I used when the rotten egg smell was present was Shell. I filled up with Sunoco that week. I also did 100% city driving then drove on the highway for 2 hours. Maybe that cured it? Anyway, again, thanks for the replies. I almost wasted $300. Thank goodness for BITOG.

 

[lexus114]

Originally Posted By: dwendt44
I would think a good long run on the highway would get things hot enough to clean any small pockets of contamination even if that's what you have there. But as had been said, CAT stink comes form the tail pipe.



Yeah, I`ll agree with that....My Cat Missy`s stink comes from her tailpipe as well.

 

[Benzadmiral]

I keep thinking you're all talking about felines who have issues with their litterboxes. . . .

 

[dwendt44]

Not the litter box. Gastrointestinal gases.

 

[dailydriver]

'Cheese Bombs' as my son calls what comes out of the tailpipe of his very large cat.

 

[440Magnum]

A good general rule of thumb: whenver you think your car has a bad catcon and you're about to change it... DON'T. They really, REALLY don't fail very often, and when they do its usually not some slight, subtle loss of power, its no power at all and sounds like the exhaust is blowing through a soda straw.

 

[antonmnster]

You shouldn't be smelling your own exhaust through the HVAC or the engine bay unless you've got some major problems.

Otherwise, rotten eggs smell is caused by a cat that's overloaded and releasing sulfur dioxide rather than carbon dioxide.

First thing to look at is a CEL, then a lazy O2 sensor.

 

[urchin]

If yo udo a lot of short trips that don't allow the cat to get up to the proper temp for a long enough time it could decrease its efficiency.


If it were my car I would head out and get the thing out on a highway were I could cruise at about 65 for an hour or so. That is about the best self cleaning you can do for a converter.