Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Why does it do this

Try a differant brand of gas. This can help.

When I had my sulphur smell, it was due to a bad O2 sensor. Changing it fixed it. You case is interesting though....

For all who are interested. Sulfur (in gasoline) that burns in combustion produces SO2 (sulfur dioxide) which in water becomes H2SO4 i.e sufuric acid. No rotten egg smell.
Sulfur in gas that makes its way to cats in raw gas is catalyzed to H2S hydrogen sulfide and eventually to oxide form if cat can handle volume and has an O2 supply. Thus rotten egg smell may be combination of a too rich an air fuel mixture , higher sulfur content and possibly low efficiency cats. Ford would like to blame oil companies (they do) but I think they designed emmissions system too close to limits. Notice that usually rotten egg smell is present when pushing hard with acceleration not when driving sedately. Thus even if O2 sensors are not showing any problems themselves or any cat efficiency issues it could still be an O2 sensor but my bet is on marginal programming within Ford's engine management system which interprets the O2 sensor readings and adjusts the air fuel mixture. Probably keeps it near rich.
Also notice how often you notice the problem from other cars and judge where problem is accordingly.
Here is Canada Ford may have issue with the use of MMT as an octane booster (thanks Ethyl Corp) since it does interfere with sensors (and is a neurotoxin to boot) but that is another issue. However it does contribute to the problem.

it means your car is running a little rich, or your not firing all 6 cylinders which is doubtful if your not witnesssing other problem like your engine running rough. it doesnt burn all the fuel. and your catalytc converter converts it in to that suffer smell, type of chit.


wow, this all from the knowledge i gained on ceg. this sites great.

Originally posted by lkinley:

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It may be a symptom in that it is the CAUSE.

-Lance

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I see what you're saying. I never knew the cause of the sulfer smell, I just always associated it w/ bad cat. This thread is interesting...learning a lot.

Originally posted by dellowm:

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For all who are interested. Sulfur (in gasoline) that burns in combustion produces SO2 (sulfur dioxide) which in water becomes H2SO4 i.e sufuric acid. No rotten egg smell.
Sulfur in gas that makes its way to cats in raw gas is catalyzed to H2S hydrogen sulfide and eventually to oxide form if cat can handle volume and has an O2 supply. Thus rotten egg smell may be combination of a too rich an air fuel mixture , higher sulfur content and possibly low efficiency cats.

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This is interesting, I'm a freshman in college and going into engineering so I am just learning the details of this very process in Chem 115. It's a bit daunting to look at some of this stuff, gotta work my way up the food chain of education...