Egads!! Whats that smell? | Ford Explorer Forums - Serious Explorations

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Egads!! Whats that smell?


Explorer Addict
September 24, 1999
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City, State
Bloomington, IL
Year, Model & Trim Level
'92 XLT
Now, maybe I'm crazy, but I have a mysterious odor coming from my truck!!

I have only noticed it recently, but when ever I have been pushing my truck fairly hard, (muddin, etc.) I have noticed this distinct smell of a sulfur-like quality. I have mudded enough to know what mud on my exaust manifolds, baking smells like, and I don't believe thats what it is.

Any Ideas? Could this be a problem? Any help would be wonderful!!


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'92 XLT

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Hey, I remember reading in the haynes manual somewhere about what exhaust smells mean, but I couldn't find them, I tried looking for it for like 15 minutes but had no luck and I don't know what to look for in the index. If you have a Haynes, or maybe a chilton has it in it, then check it out and see what the smell means. I wil tell you waht it is if I ever find it out.

If I remember correctly, a sulfur smell under hard acceleration is the sign of a catalytic convertor going. I've started to notice it in my truck too, but I keep hoping that it's the car in front of me ;).



Sulphur=rotten egg smell=catylytic convertor.

Check your cat. That's your problem.

"Nerves of Steel; Brain of Chipmunk"
'99 Eddie Bauer 4x4 4.0L SOHC aka "The Jeepeater"
Dead Link Removed
"What the heck is he doing out here in that thing???"

Before you spend money on a new cat, change your brand of gasoline for a couple of tankfulls. What you are smelling is sulfur dioxide. The source of the sulfur is the gasoline. When catalytic converters were first introduced the "rotten egg" smell was not uncommon due to levels of sulfur in the fuels available at that time.

The rotten egg smell comes from hydrogen sulfide and implies the exhaust gases are too rich (i.e. too much gasoline vapors) and not sufficient oxygen to burn (oxidize) the hydrogen sulfide (which burns easily). The cause of this could be the catalytic converter - but more likely the oxygen sensor in my opinion. A sickly O2 sensor can cause the air/fuel ratio to be off and this will cause the H2S rotten egg smell. Or it could merely be the result of changing engine RPM and engine load "quickly" and the air/fuel ratio not adjusting quickly enough. I sometimes get a little of this smell out of my 91 XLT with some 120,000 miles and original "Cat" and O2 sensor.
Mike in Seattle

hmmm...well, i never get the same type of gas twice, and i have always noticed the smell when i get up on the acceleration. should i get the same kind of gas each time i fill up? Does octane have somthing to do with it? Cause this time i notice more of the smell, and i got 90, cause it was $1.70, rather than 87 which was $1.84. this 90 also had 10% ethanol. could this have anything to do with it too?

I don't really know what your problem is riff, but maybe there are some dead fish from the river stuck up in the frame or something...Just a thought...



I don't believe the rotten egg smell means you have a bad cat. Whenever I drive my mom's 99 Limited hard it makes the same smell. I asked one of my friends that is a mechanic and he says the smell comes from when the exhaust gasses heat the cat up higher than usual and some of the catalyist actually melts. This isn't bad for the cat unless the melted catalyist clogs it up, you can tell when this happens because you see a dramatic drop in performance.