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Catalytic Converter stench

Posted by shjr (My Page) on
Tue, Aug 9, 05 at 10:37

I've got an '04 Mazda 6 that I'm completely satisfied with except for the rotten egg smell I notice just about every time I get out of it. I'm assuming this is the catalytic converter doing this, right? I've been told by a few co-workers to try a different octane of gas or add some kind of gas treatment. I've been told to just get on the highway and floor it to "blow it out". And, I've been told there's NOTHING that can be done about it.......... So, I'm asking "ya'll".... Is there anything I can do? Or am I going to have to just deal with a car with a bad "fart problem"? Thanks for any replies......


Follow-Up Postings:

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RE: Catalytic Converter stench

If the car is started, driven a short distance, and then shut down, you might notice quite a bit of odor coming from the exhaust. However, this should not happen after a long trip, 20 miles or more. It isn't necessary to floor the accelerator to heat up the catalytic convertor to operating temperature, all you have to do is drive the car for 15 or 20 minutes. You don't want water accumulating in the exhaust system, because this will cause corrosion from the inside out, and you will have to replace parts after only a few years. Longer trips will result in less moisture accumulating in the exhaust system.


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RE: Catalytic Converter stench

The rotten egg smell of the exhaust is fuel related. It is usually from sulphur compounds in the fuel. The catalytic convertor converts these compounds, therefore this odor is a sign that the convertor is working. One compound found in the exhaust may be sulphuric acid. This varies greatly from supplier to supplier and has nothing to do with the octane rating of the fuel. Changing brands may or may not reduce the odor, but is worth a try. I prefer using fuels that are low in sulphur content.

The reason that changing brands may not fix the problem is that several local filling stations may all be getting their fuel from the same tanks at the distrubition center with the only differences being blends and additives.


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RE: Catalytic Converter stench

It probably has to do with you driving like a bat out of hell. You have a new car and your probably flooring it at every light, and driving in too low of a gear. This is probably overheating the cat and making it stink. Try to keep the rpms in a normal range so the cat is not being super heated and then cooled all the time.


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