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'05 LS6 V Stealth Grey; '14 Z71 SLT Sierra 1500 Stealth Grey
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Discussion Starter · #1 ·
Weh standing behind my car I have smelled rotten eggs coming from the exhaust. One of my friends said that means something isn't buring properly, or something. Anyone know about it?
 

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A rotten egg smell emanating from catalytic converters is common. It is usually at its worst with new cars, decreasing as the car gets more miles on it. It usually becomes unnoticeable at idle for cars more than a few months old. The presence of this smell does not necessarily indicate a problem. You may have a particularly sensitive nose. The smell is hydrogen sulfide gas that, along with oxygen, is a byproduct of the conversion generated by the catalytic converter. Excessive hydrogen sulfide can be an indication of too much unburned fuel getting through the engine, but if there is excessive unburned fuel, the Check Engine light would normally come on. A "bad" catalytic converter, assuming that means one that is not functioning, would actually result is less hydrogen sulfide.
 

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'05 LS6 V Stealth Grey; '14 Z71 SLT Sierra 1500 Stealth Grey
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Discussion Starter · #5 ·
My car has about 18,000 miles, so its not so new. I just had the oil changed and I only use sunoco 93 or 94. If its not doing any damage I'll have it looked at when I get the new rear in a few months.
 

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Let us talk politics, since we have a shortage importing the good iraqi oil and getting more of the Saudi oil that I read one time that is high in sulfur and costs more to refine.... so wether it's a new car or old, every body is complaining about the rotten egg smell, mine too.... so it must be the gas that is causing those problems

:cool2:
 

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Original poster of this thread was from Jersey, if I recall. They have federal reformulated gasoline statewide there, with sulfur level capped at 150 ppm. In that case, it doesn't matter where the crude originated or what brand/grade of gasoline it is.

Definitely a hydrogen sulfide issue, coming off the catalyst. Could be a cat problem, or it could still be a sulfur contamination issue. Couldn't hurt to try another brand of gas, in case its a fuel contamination issue. Did it just start on your last tankfull?

Brian R.
 
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