My '91 Explorer got a rotten egg smell sometimes

[Daddytexplorer91]

I have a 1991 Ford Explorer 4x4 xlt with a new (2year)catylitic converter and after market exhaust system,K&M filter,and was wondering why SOMETIMES when I give it gas(almost pedle to the metal {entering a freeway,passin someone snoozin on the road}) I smell an awfull smell of eggish like fumes commin' from my vehicle,what's the problem? Please help,Thanx

 

[IZwack]

Maybe a rich fuel mixture - which could be related to an engine that never reaches nominal operating temp (think Coolant Temp Sensor).

 

[YBCold]

i thought only bad batteries do that. i guess your car has too much gas lol:

 

[94EddieBauerRock]

One of my friends had the rotten eggs smell in his vic last summer. It was so bad we could barely stand to ride in it. Eventually it went away on it's own. He started buying gas at a different station and the smell stopped. Just an idea.

 

[my pos mounty]

This is also an indication that your catalytic converters could be plugging up.
If it is an occasional odor, keep track of where you buy your fuel and if it is one station, stay away. Do you have a valve guide possibly going or are you burning oil at all? This could be a cause, because that would clog the catalytic converter, resulting in the stink. For short term, ensure you get the truck up to operating temp every time you drive it (as izwack said).

 

[NYMount21]

I run 93 octane at all times and get that smell from pushing the mounty hard (like going really friggin fast lol) and I find that it comes when the engine has just worked very hard, but I never considered it a problem. My mechanic friend once told me it was just the result of the chemical reactions at high temperatures occuring when the vehicle is working that hard. Its not something that occurs on a regular basis for me, thats odd that it happens often for you. I am kind of curious as to what it is also.....

And I have a completely different truck mind you, 2000 5.0 hmmmmmmmmmmmmmmmmmmmmmmm

 

[Tshark299]

We had a Caravan that started to smell like that... turned out to be a bad oxygen sensor that was making the engine run very rich.

 

[Daddytexplorer91]

Thank everybody , I'll try all your replies and hopefully one or two of them do the trick.
Any more suggestions out there...91 Explorer XLT 4x4 4.0 EFI