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Sulfur Smell from Toyota 4Runner

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  • rogers12rogers12 Posts: 140
    I don't think a comparison with another vehicle is necessary. What I think you should compare is the CO in the 4Runner with the outside air perhaps on top of the truck. I don't think any increase in CO would be allowed.
  • There's a ton I don't know about emissions technology, but I can offer a few bits (and some speculation) for those who are interested in this angle on the smell issue.

    First, measuring CO inside the cabin may not be a good indicator of how much exhaust (or smell) is getting in. CO is a product of incomplete combustion, an overly-rich mixture IIRC, but it appears that even bad-smelling vehicles may not produce enough to cause concern. Today's vehicles usually burn too well to produce significant CO, and one hears occasional stories of attempted suicide-by-auto-exhaust where the only result is a really bad headache. Also, most vehicles bring in some outside air even while on recirculate, and a temporarily high CO reading could come from the clunker in front of you. Finding persistently high CO in the cabin would definitely be bad and actionable, but this may not help the smell issue much.

    kheintz1 has posted a link (thanks!) on the main 4Runner thread with some good information: http://www.swri.edu/10light/catalyst.htm I could extend this a little to say that vehicles today run in a "closed loop" mode most of the time, where they use oxygen sensors to provide continuous feedback (that's what "closes the loop") on fuel mixture. They appear to try to run as lean as possible, to reduce emissions and improve fuel economy. They don't want to run too lean, though, because of the risk of detonation and engine damage. Under heavy throttle the risk of detonation due to overly-lean mixture is much greater and many (most? all?) vehicles switch out of the closed-loop mode and run extra rich to prevent detonation. Fuel actually cools the engine components. They can't run closed-loop in these situations because the speed of reaction of the oxygen sensors and the rest of the system is just too slow to ensure that they don't get too lean and start to detonate in the transient conditions of heavy acceleration.

    In the 4Runners there are extra technologies at work. Both the V6s and V8s have *heated* O2 sensors (one on each side), presumably to get accurate readings and lower emissions while the engine is still warming up. The V6s (but not the V8s as far as I can tell) also have a pair of air/fuel ratio sensors in the exhaust headers upstream of the regular O2 sensors. I'm guessing that these additional sensors help out at times when the regular O2 sensors are too cold or too slow or something like that.

    The presence of these additional sensors may help explain the difference in smell behavior of the V6 and V8 models. I suspect that heavy smell production is a consequence of a very specific combination of factors that don't happen very often in most vehicles, but in others (maybe due to marginally-performing O2 sensors, for example) these conditions are frequent and persistent. That would explain why most modern vehicles will stink bad once in a great while, but only a few of them stink consistently.

    Of course the other factor here is how/why the stink gets inside the vehicle, and why the 4Runner may have a specific problem in this regard. Lots of other posts cover that, so I won't say more here.

    I suspect that if one ran a data logger to compare a stinky vehicle with a non-stinky one while driving the same route under the same conditions one would see some sort of clear difference. The data logger could plot things like O2 sensor readings, throttle position, fuel flow, mass air flow, RPM, ignition timing, and many more. I can only speculate, but I'll bet that the sensors in stinky vehicles are a little off in their readings, and this interacts with the software in the engine computer to cause frequent, brief, periodic mixture "excursions" to the rich region which burn off the sulfur in the catalysts and cause the smell. The sensors in question may be in spec, but are off enough ("lazy" in the words of rcgator's tech) to trigger the problem. This could be the fault of the sensors or the computer software or a combination of both.

    One logical experiment is to just change out both O2 sensors, perhaps one at a time. They're not terribly expensive, but I suspect it would still cost a couple hundred dollars or more, including labor.

    user777, I think you may be on the right track in also speculating about fuel delivery problems, especially where catalytic converters are ruined. I think you can ruin them by getting excessive unburned fuel to them, and I believe they overheat in these cases. AFIK, all modern engines don't actually measure the fuel delivered by their fuel injector systems. They just know the amount a normal injector will deliver (CCs/minute) under normal fuel pump pressure, and calculate fuel flow based on how frequently and how long the injectors are commanded to open by the engine computer. The injectors are just simple on/off devices, so this is easy to do. But if an injector flows too much or is stuck on or is slow to respond, the computer and entire emissions system can be thrown off.

    Sorry about the long post. I hope it's been worth the bandwidth for somebody!
  • rogers12rogers12 Posts: 140
    Good post. My reason for evaluating CO in the passenger compartment was to either ease people's minds about exhaust gases or to find if the levels found were dangerous. I agree that normally the CO levels in exhaust are very low, but if the system is malfunctioning, then I would not assume that normal CO levels are found in the exhaust. If people are smelling the sulfur-containing emissions in the passenger compartment, then this might be an important issue since obviously there is some exhaust gases getting into there.

    Secondly, to eliminate the contributions by other vehicles, this would need to be performed away from them, at least for a significant period. Either that or subtract the levels found outside of the vehicle from that inside. Either way, knowing the CO levels found or knowing they are less than detectable by a sensor is important. To me, the smell is a secondary issue. The primary issue is determining if there is significant ingress of exhaust gases into the passenger compartment under normal operating conditions.
  • I couldn't agree with you more:

    "To me, the smell is a secondary issue. The primary issue is determining if there is significant ingress of exhaust gases into the passenger compartment under normal operating conditions."

    I do have a CO alarm in the car, but it's up front by me. I should put one in the cargo area since the smell always seems to originate from back there anyway, and I assume that the exhaust fumes are coming into the car from somewhere in the back.

    My CO alarm is one of those that would go off if the CO concentration got to a certain level, but not one that gives me a readout of ppm or anything. I think I'll get one of those to put in the back. The alarm has never gone off, by the way.
  • 4rnr4rnr Posts: 25
    I have tried driving around with a CO detector(type that goes off after a certain level) that I attached to the rear headrest support and the alarm has not gone off. My '03 Ltd. V8 creates a minor smell , say every 4 th. day of driving. What does concern me more is the fact that it inhales the fumes from the cars in front of me for eg. a diesel golf made the Runner a total stink bomb. I know now that the recirc. button must be on when doing city driving.
  • rogers12rogers12 Posts: 140
    I agree. I would rather inhale the exhaust from my vehicle, since it is minimally contaminating my interior, than that of the many cars in front of my with unknown engine maintenance and emissions.
  • tacovivatacoviva Posts: 116
    Anyone consider long term exposure. Even small amounts over time can be very detrimental. Since CO builds up in the blood stream, there are serious long term consequences of it entering the cabin, even at low levels.

    Something to think about.
  • I spent several months researching SUV's and couldn't wait for the 2004 4Runners to come out. I was pretty well set on purchasing a Sport with the V8 or possibly a Limited. About 2 weeks ago I test drove a Limited with the V8 and almost gagged when I lowered the rear window at 70mph. The salesman "acted" very surprised and said "Gee I'll have to get the service department to check out the Catalytic Converter". Not knowing of the problem I accepted his explanation of a "defective converter". Other than the "STINK" I loved everything about the vehicle but wanted to wait until a few Sports came in before picking out a model, color etc.

    Then a few days ago I happened on this particular forum and I am back to square one as far as looking for a vehicle. For 30 to 40 thousand dollars there is now way I'm going to take a chance on one of these "stink bombs". Anyway thanks to all who have posted here and to Edmunds for a great service.

    Anyone have any suggestions on a new vehicle? I live in the snowy Northeast so 4WD is a must, V8, real frame, not to too huge, $40,00 tops.

    Brian

    Maybe I'll keep my old F150 and pick up a BMW Z4 or a 2 year old Boxter.
  • Taco, I was very concerned about this, especially since I do a lot of driving around the city with the four kids in the car.

    When I found out that the smell I was getting was from my tailpipe, the first thing I did was consult with my kids' pediatrician. I spoke to three doctors in the practice, and they all assured me that CO has to build up to a critical point in one acute instance in order to cause damage, and that it does not, in fact, have cumulative effects because it does not build up in the body. Assuming you have not been exposed to large amounts, once you start breathing oxygen again, your body's oxygen level returns to normal (treatment for those who are exposed to large amounts, like firefighters are when fighting large fires, includes the use of hyperbaric oxygen chambers to reestablish normal oxygen levels).
  • user777user777 Posts: 3,341
    was both a pleasure to read and very informative. an exceptional good use of bandwidth. thanks.
  • Keeping you old F150 and picking up either a BMW Z4 or a 2 year old Boxter is not a bad trade off.
    From what has been written on this forum, some people never experience these odors and others complain of the smell all the time. I would rather buy a truck that never breaks and find a solution to this only problem.

    I spoke with the owner of a detail shop about his experience with his 04 V6 Limited 4Runner. He pulls a 3000 lb. boat with ease. He is very satisfied with this truck. He traded in a 2003 Dodge pickup and really took a beaten, he did not say how much of a loss but said it was substantial. The Dodge had some quality issues, so far his Runner has been perfect.

    I asked him about the sulfur odor. He said when he accelerates hard with the back window down he gets an odor only one time, after that he has no problem. He went to a muffler shop and they advised the fix was to cut the tail pipe and replace the tip with a curved pipe that diverts the exhaust to the side. Cost was about $80.00.

    This is the same fix that others have suggested in this forum. I agree that Toyota should repair this if it is a real problem.

    I have decided that if I experience the odor with my new 4Runner, I will not wait for a recall or a TSB to correct it. I will either try the $80.00 fix or most likely have the Borla system installed which also is side exhaust.

    Has anyone had their exhaust diverted to the side to correct the odor problem? How well did this work? Where did you have it done? Cost?

    I do not believe, for the money, there is a better midsize SUV on the market then the V6 or V8 4Runner. At this time, I will never consider anything other than Toyota/Lexus or Honda/Acura products. I have had costly experiences with other makes and I do not believe they are anywhere close to Toyota or Honda quality. Just look at resales. When my new 4Runner arrives I will sell my 2002 4Runner (have it presold) Sport Edition with 37,000 miles for $24,500.00. Two years ago I paid a little over invoice, $31,259.00 for this truck. I do not consider this a substantial loss. And a dealer would sell this same truck certified for around $28,000.00. Try getting that value out of a two year old domestic.

    My truck may not arrive for a month. After I break it in, I will post if I do or do not have an issue with the sulfur smell.
  • rcgator, my understanding of this hazard matches yours. CO is not toxic in the ordinary sense, it's just that it binds much more tightly to the hemoglobin in blood than oxygen does, displacing the oxygen that keeps the brain alive. If the CO exposure is temporary or slight, the blood concentration of CO goes up for a time, but doesn't get high enough to be a problem and it eventually falls.

    That's why the treatment for acute exposure (high CO concentrations in the blood) is a hyperbaric chamber, where the high partial pressure of oxygen can drive the CO out of the blood much more rapidly than at normal pressure, preventing further damage.

    As a practical matter, of course, it's undesirable to have much exhaust get into the cabin, even if CO is low. That's why Toyota's choice to place the exhaust outlet at the back of the vehicle instead of the side continues to be a puzzler to me. They're an engineering-driven company and usually have a reason for what they do, but I can't fathom it here.
  • swschradswschrad Posts: 2,171
    it binds it like cement in a drainpipe. hemoglobin is pretty good about releasing oxygen to cells, and taking up CO2 and releasing it in the lungs... but when it gets sludged up with CO, it is very difficult to get it to release the poison and take up either CO2 or O2 again. best results for CO poisoning are received when the patient(s) are locked into a decompression chamber that is overpressurized with medical oxygen.. and left there for a day. HCMC is the only hospital around these parts with a hyperbaric chamber for the purpose, it holds 8 patients at a time.

    it's pissy nasty stuff. you don't want any if you can avoid it.
  • For what it is worth. I have been having the horrible smell INSIDE the cabin of my V-6 2003 4-runner since day one. I have tried every manufacturer of gasoline and every grade of gasoline within 50 miles and the problem still occurs. In addition, these stations are in the reformulated section of the country. So lets hear some more about how gasoline is the problem…
    I have never been in a vehicle, other than this one, that you could smell your own exhaust while driving. Can one of you car salesman or service managers on this posting tell me how this happens? Notice I didn’t say problem, since Toyota thinks this is NORMAL for a vehicle and not a problem.
    Windows up or down it doesn’t make a difference.
    To bad the only thing that is ever going to resolve this issue is class action.
  • driftracerdriftracer Posts: 2,692
    at if you approach a lawyer with the only proof being your own nose and statements from people on an internet chat board.

    To initiate a class-action suit, there are several stages - without solid evidence, the first couple of stages will not happen. The final stage is getting it certified by a judge, where the suit is allowed to proceed. Won't happen without more that idle gossip.
  • I bought my Runner from the dealer with the Borla dual side exhaust installed at the factory/port. I have noticed on rare instances the sulfur smell. The smell can be induced. Just stomp the gas pedal from a stop with the rear window down. But, I do not have a lingering smell problem. Not enough of a smell problem to start a vindetta with the dealer or Toyota. So, in theory, the dual mounted side exhaust works. Before you spend $$ with an 'ambulance chaser', I would check out Borla. You can buy the dual Borla for about $605 and it can be installed easily in your garage using a 14mm socket wrench and rubber mallet. Or, any local exhaust shop can install it in their sleep.
  • Has anyone had the Borla Exhaust System installed on their 03 or 04 4Runner? Did this eliminate the sulfur smell?

    And has anyone had the exhaust pipe modified to exhaust to the side? Did this eliminate the sulfur smell?

    Any other fixes -- different gas brands, catalytic converter replaced, dealers repaired something else?

    If a simple fix like modifying to side exhaust or replacing with the expensive Borla system solves this problem, maybe Toyota will use this information for an eventual recall.
  • Thanks sacstate1.

    $605.00 to install yourself is not bad. Plus you have the benefit of additional HP and Torque. You stated in a previous post that this added more power?

    This may be one solution, probably diverting the pipes to the side will also work.
  • Well, Borla claims there is an increase in hp and torque of 10%. I can say the system has IMMEDIATE throttle response. I don't recall my test drive with a non-Borla OEM V8, so I can't compare to what I have. But it sure sounds nice and the 'punch' will definately push you back into the seats similar to the Cobra SVT that I used to own.

    Price of $605 was found by another member in another 4Runner forum.
  • Driftracer, why are you on this message board? Please show me one posting of yours where you have contributed anything to the discussion except the Toyota is wonderful mantra?
    Unfortunately you are right with regards to class action. It’s not worth the effort.
    I guess that is why most people feel like the only form of life lower than a lawyer is a car salesman (or the associated service manager.)
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