Edmunds dealer partner, Bayway Leasing, is now offering transparent lease deals via these forums. Click here to see the latest vehicles!
Options
Popular New Cars
Popular Used Sedans
Popular Used SUVs
Popular Used Pickup Trucks
Popular Used Hatchbacks
Popular Used Minivans
Popular Used Coupes
Popular Used Wagons
Comments
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!
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.
"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.
Something to think about.
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.
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).
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.
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.
it's pissy nasty stuff. you don't want any if you can avoid it.
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.
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.
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.
$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.
Price of $605 was found by another member in another 4Runner forum.
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.)
kirstie_h
Roving Host & Future Vehicles Host
MODERATOR /ADMINISTRATOR
Need help navigating? kirstie_h@edmunds.com - or send a private message by clicking on my name.
Share your vehicle reviews
Just think of all of the bad publicity just by word of mouth a problem like this creates. Not to mention the loss in resales to current owners of these stink mobiles.
I can just hear the conversations all over America..."Gee Fred, why didn't you buy another 4Runner?"...."Well Joe, it looked great, ran great, had lots of power, rode nice, had an awesome stereo and was dependable but it smelled like a rotten egg stuck in an old wet sneaker"....Huh????
I may hold off on buying a new vehicle until the springtime so I'll be watching the posts to see if Toyota solves this problem, until then;Good Luck to all of you.
Now that I’ve turned into a wait and see mode for an SUV, I actually started looking for a minivan to make the wife happy, and Sienna is off the list for the same reason. I’m seriously considering a domestic brand. To my surprise after all these years, it is actually pretty good, especially the AWD version. I want to remind you guys that there are still other carmakers out there selling cars.
For those who’s trying CO detectors, I remember OSHA’s standard on CO level is 50ppm for 8 hours, meaning it’s not safe for an 8 hour shift if CO level is above 50ppm. Also CO detectors won’t go off until it reaches 70ppm for at least 60 minutes (UL2034). I’d suggest a battery operated CO detector that displays CO level and has a peak level recall function.
BP and Amoco have merged in MD. I use 87 mostly.
Why do we have roll down windows if we can't use them? It was a big selling point for me until I was driving with it and keeled over based on the smell. It's like putting windows on submarines. Why bother? I guess you can extend the occasional lumber or x-mas tree out the back window (as long as you don't pass out due to CO poisoning!) Really, why have the roll down rear window? I don't spend much time in the vehicle parked, and if I do I open the hatch all the way (makes a nice place to get out of the rain). Roll down window=stupid now that I know it totally sucks in the exhaust. Too bad, would have been nice, like a convertable.
It sucks fumes in - isn't that obvious? Tie the tree to the top, or get a truck -
Why should it be obvious that the back window would suck in fumes when down? Convertibles don't suffer this problem with the top down.
If I shouldn't drive with an orifice open, does this mean I can't drive with my sunroof open? Or my drivers window open? Or any windows open? They are orifices, right?
Please help me out and post a list of all the features on my vehicle I shouldn't use because of inherent design flaws. BTW I thought my 4Runner is a "truck".
The rear window in your truck is made to be rolled down for loading, or while you're at the park and want to drop all of your windows - whatever you need.
I didn't say "an" orifice as in any opening - please read my post before you go on the attack - I said your rear hatch or rear window.
Just thought I'd remind those of you that think you've fixed your problem by changing your gasoline source.
In any event, I went and drove a Honda Pilot (getting ready for the trade-in.) The Honda dealer wants to keep my Toyota on his lot for people to test drive that are making the Honda/Toyota decision. One drive in the Toyota stink bomb and any consumer will be convinced. I even offered to give the Honda guy my maintenance receipts where Toyota says this normal and is a gas realted problem. He is so excited but I am not that excited about loosing money trading a 6-month-old car in.
As with the other driver in MD, I did notice that 87 octane gas does make the smell worse. 89 octane smells better, anything octane above that I can’t tell whether the smell is from my seats, which permanently stink, or the exhaust.
I still cant believe that Toyota says it is normal to smell your own exhaust driving down the road with all the windows up.
Changing brands of gasoline has done nothing.
So it IS a fuel issue?
FL4Runner, did your exhaust fix remove the instance of sulfur smell entering the passenger cabin (w/ or w/o the rear window closed.)?
The rear cargo window serves almost no purpose for me, especially since you can't raise it with the remote. You must use either the key or the front dash button to raise the window again. This is hardly a convenience. It is almost easier just to open the entire hatch for loading/unloading.
even if a tailpipe extension mitigates the problem, the root-cause will remain.
it's interesting to me, that not all owners report the problem. that should be interesting to you too.
i am thinking that these cars are set up wrong, possibly something is not working the way it is designed to work - ie: a fuel delivery, combustion, emissions sensing / control, cat convertor issue could be at the root cause.
if someone does manage to mitigate the problem by more or lesser degree by say: blocking vents, extending the tailpipe, rolling up all the windows, keeping it easy on the gas, driving with higher octane, etc...
the root cause remains.
yes/no?
also - if these owners are smelling sulfur, it isn't a great leap logically to assume those that aren't reporting the problem, might very well be getting gases into the cabin to which they are unaware.
regards.
I pointed out that you shouldn't ever operate a vehicle with a rear window or hatch open - any vehicle - been that way a LONG time.
I'm on the fence on this issue and will continue to be, for what that's worth.
All I've seen and heard is unsupported complaints - there's been no data that there are harmful levels of anything. Just because you can smell it, it means nothing.
I have a very senstitive nose, and on a good day, if the wind is right, I can smell the farm that's over 3 miles away. On some days, it's pretty strong.
I seriously doubt that manure gases and bovine flatulence have caused me any ill effects, simply because there's enough in the air to smell.
The courts don't care about perceptions, they care about what can be proven through evidence. I haven't seen any here yet. Talking about suing a manufacturer and buying billboard space is pretty silly and wasteful unless you have something to give a judge other than "I can smell it, can't you?".
I thought about forcing air into my vehicle then detecting air leaks outside the vehicle to try and locate how exhaust may be getting in. I can try running the truck with taking in fresh air and setting the AC to blast at it's highest setting, but I doubt this will create a high enough pressure for me to detect something outside the vehicle. Any suggestions?
I think exhaust leaks in around the back because if I run with the AC on fresh, the cabin smells clean. So I doubt exhaust is coming in from the front (near the air handling piping) or else I would smell it coming out of my air vents. I strongly suspect it is seeping in from the back hatch (wherever the exhaust circulates around after exiting the tail pipe). What are your opinions?
Also The rear window is used when loading and unloading. My '87, '97 and '03 4runner OWNERS MANUAL all specically say NOT to drive with it open as exhaust fumes will enter the compartment. Even though you aren't supposed to use it while driving I still think it is an advantageous design. I have found it VERY useful on several occasion as I have been driving with this feature for a very long time.
fl4runner, I know for sure that the exhaust is coming in from the rear of my car (a 2003 Sequoia) because my kids always smell it first, then it takes a few seconds for me to start smelling it in the front of the vehicle. I know these are two different trucks and two different designs, but I suspect that the fumes are getting in in a similar fashion in both vehicles.
I also don't use the fresh intake on the AC because it just stinks too much to be sucking in the exhaust from the cars in front and around me, and, you're right, it's just way too humid in Florida.
So far, sealing that rear vent and changing the O2 sensor have not fixed the problem. My husband promises me he'll have the tailpipe extension done this weekend. I'll let you all know if that works. If it doesn't, it's back to Kendall Toyota and time to start looking into Lemon Law proceedings.