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Rotten Egg smell exhaust

wsommarivawsommariva Posts: 157
edited March 2014 in Volkswagen
2000 Jetta VR6. In the mornings with a cold
engine I get a very strong, very bad rotten egg
smell. Anyone know what the cause and fix is?


  • btroybtroy Posts: 92
    There may be a problem with your emission control system, but if you are lucky it may just be the gas you are burning. Some fuels contain a higher amount of sulfer which can cause a smell like eggs. Try buying gas at a different gas station located in a different area, preferably a name-brand place like Phillips, Exxon, Texaco, Shell, etc. Get the premium stuff just for good measure. See if that helps. Hopefully that's your only problem.
  • I use AMOCO now but will switch to see if that does it. I heard that it might be the catalytic converter. I have an e-mail into my dealer to see what they say.
  • burdawgburdawg Posts: 1,524
    Some smell of this type is normal, especially when first warming up. The by product of the cat converter is hydrogen sulfide, which of course smells like rotten eggs. If you think it's excessive, have it checked.
  • does smell only in the morning when the engine is cold. Will this hurt the engine?
  • burdawgburdawg Posts: 1,524
    Usually this odor is normal and varies in intensity between makers. When cat. converters first came out, it was a big issue, but I guess people are used to it now. If your in doubt and for your own peace of mind, have it checked. If the cold start mixture is wrong, it could cause the odor to be intense. Will this cause any damage? Probably not, but VW will know best (well,they should anyway).
  • ....I am waiting for an e-mail answer from my dealer.....
  • torektorek Posts: 92
    The smell is indeed sulfur compounds, usually hydrogen sulfide (H2S). It is not the catalytic converter at fault though; the problem is a combination of too much sulfur in the gas in the first place, and funky combustion in the engine.

    Ideally (as far as combustion goes anyway) gasoline would be pure octane (C8H18) and would burn 100% cleanly, producing CO2 and H2O via the reaction: C8H18 + 17 O2 => 8 CO2 + 9 H2O. Gas is never pure octane though, and besides the deliberate additives, it contains sulfur compounds. Sometimes these burn in an "2H + S" kind of reaction and produce H2S, and sometimes the sulfur burns with the O2 and produces SO2 (sulfur dioxide) and SO (sulfur monoxide). The H2S is the stinky stuff, while SO and SO2 combine with water to make H2SO3 and H2SO4, or sulfurous and sulfuric acid (components in acid rain).

    All a catalytic converter really does is "finish up" the burning of various un-finished combustion compounds, typically adding an oxygen atom or two. This gets rid of some smog-causing compounds, especially partially burnt hydrocarbons, at the expense of increasing other acid-rain-causing compounds (the sulfur oxides, and also nitrogen oxides).

    The US government is cranking up the pressure to reduce sulfur levels in our gasoline, to reduce both H2S and SO/SO2 emissions. This will cost you at the pump, but save you at the grocery store (less crop damage, more fish surviving to the freezer, etc.) and doctor's office (healthier lungs -- free-floating SO2 gas turns into sulfuric acid when it hits the lining in your throat and lungs, ugh) so it is kind of a wash. In the meantime, you can indeed try different brands of gasoline, as different crude oils have different amounts of sulfur to start with, and some refineries remove more or less than others.

    As for producing H2S instead of SO2: in general this means your car is running on a rich fuel mixture (less O2, more gas => sulfur has to combine with the H's rather than the O's as there are not enough O's to go around). Cars are of course supposed to run rich while cold. How rich is another question -- if it is too rich, you can get carbon deposits, which can foul the sparkplugs or get inside the cylinder and cause knocking and dieseling. This can occur if the emissions system (oxygen sensors etc.) are not working right. On the other hand, it could just be that you have a highly-sulfurous gasoline and everything is working the way it should.
  • btroybtroy Posts: 92
    You just made that up, didn't you?
  • torektorek Posts: 92
    Seriously, the above is just high school chemistry: oxidation of hydrocarbon chains is a nice exothermic reaction. It has been a lot of years and I would be hard pressed to actually show the equilibrium reaction rates and thermodynamics equations and all, but the "so many of these molecules + so many of those molecules => so many of these other molecules" part is easy.

    (Octane is also easy to remember, since after butane they just count up in Greek: heptane, hexane, septane, octane, nonane, decane. What was 11 again, undecane? Twelve would be duodecane. Shortly after that you get into kerosene and jet fuel. :-) )
  • ... a few things to check out at the dealer. Thanks everyone; I hope the dealer knows his SO, SO2 stuff........
  • btroybtroy Posts: 92
    I was just kidding. I'm impressed by your recollection of chemistry. I still think he just has a rotten egg in his miffler, though ;-)
  • torektorek Posts: 92
    Actually, I figured you were kidding -- I just have a weird memory for things and I have to show it off now and then. :-)

    Egg in the muffler? Is that a variant of the old banana in the tailpipe trick?
  • butch11butch11 Posts: 153
    I live at the edge of where reformulated gas is required. Have noticed gas with ethanol stinks a lot more than the real thing (no ethanol). The stations just over the county line do a land office business selling straight gas.
  • Can i get a side of bacon with those eggs?
  • bobs5bobs5 Posts: 557
    Banana in the tailpipe trick...ha ha ha
    That was from Beverly Hills Cop right?
    I'll take a sausage with my eggs please.
  • ...we have oxygenated gas in the winter...maybe that's it?
  • torektorek Posts: 92
    I poked around and read some more bits about gasoline in general.

    In the USA, gasoline is sold by "R+M / 2" method (look at the various inspection stickers on a gas pump sometime, they have the date of inspection and certification that it meets all kinds of standards, etc.). The R, or RON, is the "research octane number" and the M, or MON, is the "motor octane number". These are two standardized tests (using a special standardized engine) to see how any given gasoline performs. When you buy "higher octane" gas it really just means it performs better on that standardized test engine (you then have to hope that this means it also performs better in your actual car engine...).

    The big desirable component in gasoline itself is not actually pure "octane" (C8H18, but with all the C's strung out in a straight line) but rather something called "2,2,4 trimethylpentane". This is also C8H18, just arranged differently. I drew one out and will see if it gets through town hall unmunched:

    H HCH H H H
    | | | | |
    H -- C -- C -- C -- C -- C -- H
    | | | | |
    H H

    As for "oxygenated" gas, at least here in CA, it has to be one of a few specific formulations. One uses something called "methyl tertiary butyl ether" (MTBE), which I dare not even attempt to draw. :-) The "ether" part is what makes it an oxygenate. An ether has an oxygen atom in the middle of the carbon chain, if I remember right. ("Plain" anaesthetic ether, as seen on M*A*S*H TV for instance, is probably the best-known ether. As they said on the show, it is explosive. But then, so is gasoline.) The other oxygenate is ethanol -- ordinary drinking alcohol. Alcohols are just regular carbon-chain molecules (just like methane, ethane, butane, etc.) but with an OH group stuck on the end -- there's your oxygen atom again:

    H H
    | |
    H -- C -- C -- OH
    | |
    H H

    From ethane, you get ethanol, just as from methane, you get methanol -- wood alcohol -- and from propane you get propanol, or rubbing alcohol ("iso"propanol anyway). (Once you get a long carbon chain, you can start attaching things in the middle instead of at the end, so chemists have a whole naming system to tell where you put which atoms.)

    In order to get the sulfur smell, there has to be sulfur in there in the first place. Whether oxygenated gas is more likely to produce H2S (vs SO2/SO3), given the sulfur in it, I do not know (out of my chem depth here).
  • guitarzanguitarzan OhioPosts: 764
    Anyone see the TV special, saying how MTBE is in all of our drinking water, and they have no clue as to the effect on humans?

    Community Leader/Vans Conference
  • burdawgburdawg Posts: 1,524
    Yes I saw it. Score one for short sighted government, who really think they can control nature. Did they really think, even for a moment, that this wouldn't show up in groundwater somewhere, sometime?
    Well, maybe a lesson has been learned, but I doubt if it will be retained.
  • light2light2 Posts: 6
    Burdawg and Torek: Why does the smell occur in only some cars and not in others?

    Have a 99 Altima and smell is not only when it's cold, but when it's warm, but not when it's windy. There doesn't seem to be a rhyme or reason to it.

    Of course, it won't happen when I take the car in for service. I've heard from dealers that it is high sulfur content in gas, but think it's a load of malarky plus sulfur, eggs, etc. because more cars would have it then.

    Replaced catalytic converter and change gas all the type. It still happens.

    Do you have any other suggestions? Again, I ask, if it's the gas, why doesn't every car smell?

    Manufacturer says there's a problem across the board, but there is no mechanical defect with my car. Service guy said technicians don't know how to fix it YET.

    Are there any others who are nauseated or think this smell is unacceptable who would like to pursue other options? Manufacturer and dealer have prevented me from doing Lemon Law, they cancelled my appointment which I needed within a certain mileage, timeframe. I'm consulting an attorney, but need others out there with Nissans or other cars that have this smell to help.

    Please let me know if you're nose has had it with rotten egg/exhaust smell inside the car! Cars should be made to run with the fuel available in your area. New cars should not have this problem without a remedy.

    Any suggestions, volunteers, ideas would be helpful for congress and/or lawyers.

    Thanks for continuing to talk about this. There is a problem.

    By the way, did you hear about the gasout in April to complain about the high price of gas? It's April 7-9. Please don't buy gas on those days and hopefully prices will come down like they did a few years ago.

    Take action!
  • mak9mak9 Posts: 5
    light2: Just got a Corolla 2000. I am having this rotten egg smell. I am under the impression it happens when there is a high humidity in the air.

    You are right, if it is the gas, then why is it not happenning in all cars?

    I have read somewhere that it could be a glitch in the computer program that controls the GAS/AIR ratio mixture.
  • butch11butch11 Posts: 153
    I live at the edge of the area that mandates oxygenated-AKA welfare support for rich farmers-gasoline. When I run that oxygenated crap in my 97 honda I get the rotten eggs-the real thing w/o the corn welfare payment additive does not stink.

    I think most of the MBTE was used in CA-maybe in 20 years the CDC can do a cancer morbidity study tied to water sources in CA and determine how many people bit the dust because some pol determined MBTE had to be used in CA.
  • domino8domino8 Posts: 2
    I have a 1999 Infiniti I30L (which is also a NISSAN)- I just posted to you in the other topic room, but I have had the problem since October. Trip to dealer - nothing they can do, not the catalytic converter "It's the sulfer in the gas from Oct-April in the Northeast"....Their best suggestion was to try different brands/stations until I find one that alleviates it somewhat. I would LOVE to join some sort of action. I can not believe that they can get away with selling you a $30K car that is like driving in a sewer. TOTALLY UNACCEPTABLE. Too bad - all other aspects of this car are great. But so much for Infiniti's "Total satisfaction guarantee".... I'm trying to get ahold of the number for the Nissan Regional Manager in the Long Island / New York region & haven't even had any luck with that......Anyone with any help?????
  • I just bought a 1996 Pontiac Sunfire and noticed the smell too. I was a little worried that I needed a Catalytic Converter but now that I read this topic, seems like everyone else stinks too so I'll put up and shut up with the rest of you. I know some lawyers out there in Michigan have set up a toll free hotline 1-800-LEMON LAW. Maybe they can help? Let me know if they do help. I work for a lawyer but he doesn't handle those types of cases.
  • pblevinepblevine Posts: 858
    What will be the affect of MTBE on us humans? You ask? It results in an addiction to the internet and a reflexive cough which sounds like "Honda". And research doctors are now finding a slight heart irregularity which rhymes to the vocal pattern of "CL". But on the positive side, these same doctors (Drs Hop, Skip, and Jump) have also found that MTBE in the blood stream leaches out residual lead from human feet. And this finding correlates to slower traffic. On this basis, the CIA has concluded that a Communist Plot is now underway, and they have requested funds to research methods of extracting MTBE from our soil for export to North Korea. Ha!
  • My mother currently owns a 1999 BMW 328i
    convertible every time her or me drive it
    and pull into the garage we will turn off
    the engine and close the garage door but when
    we open our doors this horrible
    musty smell comes from beneath the car is it the
    cattilatic converter or do all bmw's do this???
    please e-mail me
  • lucky20lucky20 Posts: 35
    The catalytic converter will always produce some odor when the eng. is running, & may produce some during cool down after the eng. is shut off. Although, the odor should be very faint. Excess odor is caused by excess fuel leaving the eng. combustion chambers with out burning & entering the functional CAT. In other words, running rich or lack of containment & or misfire.
    A number of conditions, or problems can cause this symptom. A GOOD & TRUSTWORTHY shop or mechanic should be able to run an exhaust analysis & discover the cause. The best person to talk to about this is the mechanic who deals with this problem often. I have also found a couple of customers who have ultra sensitive sense of smell & recommended they simply try to avoid the offending situation when ever possible. (allow a closed garage to ventilate)
    I have not been able to find any industry bulletins indicating fuel type or content causing this problem. No fuel co. representative, I am acquainted with, will admit to a fuel/exhaust odor production problem.
  • butch11butch11 Posts: 153
    If nothing is wrong with MTBE, then why has the EPA having gasoline manufacturer's remove it from CA gasoline. Costing them/consumers millions of dollars. A lot of govt warnings are over done-silicone breast implants, asbestos and hosts of others. The chemistry of MTBE is interesting-very reactive and a suspected carcinogen. If you want to talk about conspiracy theories, check out the politics of gasoline additives-classic confrontation between George W and McCain in IA. McCain says he would end it-George W said he thought it was a good idea.
  • torektorek Posts: 92
    #28 (butch11) talks about the Iowa debate between G.W.Bush and McCain. What McCain was talking about "ending" was the ethanol subsidy.

    MTBE is "methyl tertiary butyl ether", which is made from a toxic-waste byproduct that occurs when refining crude oil for gasoline, diesel, kerosene, etc. Ethanol is just "good ol' drinkin' alky" -- the active ingredient in beer, wine, Jim Beam, and so on. "Corn squeezin's."

    Either MTBE or ethanol can be mixed in with regular gasoline, and either one causes it to burn slightly differently in an internal combustion engine. The difference, as far as Iowa goes, is that ethanol is made from -- yes -- corn! (Hence the nickname above.) Iowa farmers grow a lot of corn. If gasoline is going to contain ethanol, Iowa farmers can grow even more corn. Great for Iowa, not so great for other people's wallets: ethanol costs more per gallon than gasoline, and more per gallon than MTBE for that matter. This is where the subsidies come in.

    Personally, I tend to be in favor of letting things cost what they cost, and not using toxic waste byproducts in places where they wind up in our drinking water, and that sort of thing. I would not mind paying $10/gal for gasoline and not dying of cancer, vs paying $2/gal and dying, or paying $2/gal with ethanol plus $8 more in taxes per average gallon as used by the average guy. (I exaggerate for effect here -- ethanol additives are only very slightly more expensive than MTBE additives.)

    The cancer link for MTBE is not yet reasonably certain, but the fact that MTBE makes water undrinkable (it smells and tastes horrible) is quite certain.
  • pat84pat84 Posts: 817
    If you think the rotten egg smell is bad now, you should have been around when Cat converters were first introduced-1968 as I remember. The common term for the smell was "rhode Phaarts" or something similar. They also had warnings not to park over combustible material, such as fallen leaves, because the Cat converters used to run so hot they could start fires.
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