# car stinks when coming to stop



## fast-ser (Dec 8, 2005)

conveter 

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my car smell like rotten egs could it be my cat convetereter


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## Zac (Mar 10, 2004)

Gas is causing it likely. What car do you have, what brand gas are you running and what octane? Running over the reccomended octane can cause the rotten eggs smell.


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## bigern45 (Oct 25, 2005)

Zac said:


> Gas is causing it likely. What car do you have, what brand gas are you running and what octane? Running over the reccomended octane can cause the rotten eggs smell.


how so? ive never heard of that....


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## Pbates (Jul 28, 2004)

Zac said:


> Gas is causing it likely. What car do you have, what brand gas are you running and what octane? Running over the reccomended octane can cause the rotten eggs smell.



I've never heard of this either. What happens to cause this smell. I run 94 octane Sunoco when I autocross and get this smell. It was starting to cause me concern and this is the first I heard of this. I thought my cat was failing.

Pete


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## neogeon (Nov 30, 2005)

stop eating eggs before you autocross and ripping nasty ones because you're nervous. :thumbup: 

although, ive never heard of higher octane doing that either, thats a shitty additive *pun intended*


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## Zac (Mar 10, 2004)

The best way to describe it is this:

"Certain high performance engines benefit from use of high octane fuel. For other engines, using a fuel with a higher octane rating than the vehicle requires sends unburned fuel into the emissions system and catalytic converter. This puts unecessary stress on the emissions system. For some vehicles, a rotten egg smell coming from the tailpipe signals use of too-high octane gas."

http://chemistry.about.com/library/weekly/aabyb100401.htm

And Sunoco doesnt make the best of best gasoline.


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## Pbates (Jul 28, 2004)

Zac said:


> The best way to describe it is this:
> 
> "Certain high performance engines benefit from use of high octane fuel. For other engines, using a fuel with a higher octane rating than the vehicle requires sends unburned fuel into the emissions system and catalytic converter. This puts unecessary stress on the emissions system. For some vehicles, a rotten egg smell coming from the tailpipe signals use of too-high octane gas."
> 
> ...



Thanks ZAC, this is just what I figured it might be. And thanks for the reference. Its nice to get good solid answers every once in awhile.

Pete


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## bigern45 (Oct 25, 2005)

how does higher octane in fuel put unburned fuel in the catalyst? the higher the octane rating is, the more stable or less volatile the fuel is. the only time that this would effect a car is during cold start up, and the fuel would be TOO stable to combust. but when an engine is running, compression and spark is good, there should be no left over hc's getting too the exhaust. once the burn process is started, fuel just wont be left over. you just have to have a hotter ignition temperature to ignite the fuel. i would say that it is not necessary to run a higher octane than what your vehicle suggests. but it wouldnt cause these problems. i do agree, though, that the fuel could have been bad from where ever. i have heard of a few cases of some sulfur in fuel just by chance, and that would cause the smell also. or you might need a new cat. i would try gettin gas from some where else and run a couple of tanks through it.
you arent using aviation fuel, are you?


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## Zac (Mar 10, 2004)

higher octane fuel than rated will cause the rotten eggs smell. if you dont mind hurting a car, run a tank or two in a car rated for regular. then run a few tanks of regular and watch the smell disapear.


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## ittamaticstatic (Nov 5, 2003)

That was interesting. I always thought oil in the combustion chamber can give you that smell.


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## bigern45 (Oct 25, 2005)

have you tested this theory? have you filled up with a higher octane gas and had this result and then switch back over and the smell disappears? i still dont agree and wonder if the "scientist" that tested this theory before he/she wrote the article a number of times or just once. if not all of the fuel is being burned i would think that you would have a misfire, which would be more noticable than the smell. it just doesnt make sense....


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## Pbates (Jul 28, 2004)

bigern45 said:


> have you tested this theory? have you filled up with a higher octane gas and had this result and then switch back over and the smell disappears? i still dont agree and wonder if the "scientist" that tested this theory before he/she wrote the article a number of times or just once. if not all of the fuel is being burned i would think that you would have a misfire, which would be more noticable than the smell. it just doesnt make sense....


I have just run 2 tanks of fuel through my SpecV of 92 octane instead of the 94 octane I was using and the smell disappeared. I guess that a test of sorts.


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## neogeon (Nov 30, 2005)

Pbates said:


> I have just run 2 tanks of fuel through my SpecV of 92 octane instead of the 94 octane I was using and the smell disappeared. I guess that a test of sorts.


I'm guessing your a mostly stock N/A spec v when i say this, but why does everyone think you need to run premium in a spec v? I find mine runs best on 89, its just 9.5:1 compression, its not an M3 with 11.5:1 or something, You aren't making it faster by paying more and in fact your probably making it run slower and gumming up your engine in the process, just because its more expensive doesnt make it better.


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## bigern45 (Oct 25, 2005)

could be also that because it is premium fuel, and because of the higher expense and being purchased less, it has more time to set and draw out more impurities from the tanks that it is being stored in, giving off funky odors from the impurities that it draws in. but it wont cause your car to run bad or slower because of the octane rating being higher than what is demanded from the manufacturer, and it shouldnt gunk up your car engine, like additives in summer and winter blend fuels will.


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## Pbates (Jul 28, 2004)

neogeon said:


> I'm guessing your a mostly stock N/A spec v when i say this, but why does everyone think you need to run premium in a spec v? I find mine runs best on 89, its just 9.5:1 compression, its not an M3 with 11.5:1 or something, You aren't making it faster by paying more and in fact your probably making it run slower and gumming up your engine in the process, just because its more expensive doesnt make it better.



Good point, I won't be running 94 in it again but the manual does say at least 91 octane. Around here (Ohio) you can get 87, 89 92,93 or 94 depending on the gas station. I can't say I've ever run 89 in the car. I'd be really pissed if it started pinging however.


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## ittamaticstatic (Nov 5, 2003)

9.5 is still pretty high and you should run a good octane to prevent pre-ignition, even though the Knock sensor will take care of it anyways, especially if you run your car hard at all. Also common sense would tell you that the high octane gas isn't purchased as much, but the news actually did a report on how many people actually buy a higher octane then they needed. It was alot. for example when the gas shortage was going on I noticed at some gas stations they only had the lowest grade available, 87. Also a higher octane is going to yield better gas milage in normal driving conditions. :thumbup:


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## neogeon (Nov 30, 2005)

ittamaticstatic said:


> 9.5 is still pretty high and you should run a good octane to prevent pre-ignition, even though the Knock sensor will take care of it anyways, especially if you run your car hard at all. Also common sense would tell you that the high octane gas isn't purchased as much, but the news actually did a report on how many people actually buy a higher octane then they needed. It was alot. for example when the gas shortage was going on I noticed at some gas stations they only had the lowest grade available, 87. Also a higher octane is going to yield better gas milage in normal driving conditions. :thumbup:


I agree that 87 is certainly too low but 89 and 93 seem to run identically with my car, in fact i think the 89 may actually run better.


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## Zac (Mar 10, 2004)

Ehhh...I wouldnt go that far. There has been discussion about better mileage on mid grade during the winter, however a dyno sheet would do the talking as far as 89 vs. 91+.

The 02-03 Spec V needs ideally 93+ because of the oversensative knock sensor and the tuning on the edge of detonation. Theoretically you can run a lesser grade, but your car will retard timing which is not something you want happening on a daily basis. I once saw a dyno sheet with a guy on 87 and it looked like an earthquake on a richtor scale. I presume it looked like this because of pulled timing. Power was low as well. The only thing I run on my car is Chevron 93 octane and if that is not available Shell V Power as these are Top Tier gasolines. The additives that are added to the Top Tier gasses make them by far superior to anything else. It's always important to consider the brand as well as octane.


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## Russell (Sep 11, 2005)

i run 87 octane and still get the smell. its not constant at all. just every now and then when i come to a stop ill smell it.


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