# Passing Gas **URL:** \ **Category:** General Discussion\ **Created:** [March 31, 2013, 7:55pm UTC](https://community.cartalk.com/t/passing-gas/78376 "2013-03-31T19:55:47Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![longprime](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@longprime](https://community.cartalk.com/u/longprime)\ **Post date:** [March 31, 2013, 7:55pm UTC](https://community.cartalk.com/t/passing-gas/78376/1 "2013-03-31T19:55:47Z")
Yesterday, after a hard day of chasing clams, several cars that passed me on a hill, had that particular odor of passing excessive, sulfurous auto gas- Why does this happen, and what is it? ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [March 31, 2013, 8:50pm UTC](https://community.cartalk.com/t/passing-gas/78376/2 "2013-03-31T20:50:51Z")
When gasoline has a high sulfur content, that odor from the exhaust is the result, and–unfortunately–some brands of gas seem to have a higher sulfur content than others… If this happens to your car, a little experimentation with gas from different stations can usually yield gas that doesn’t produce this effect. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [March 31, 2013, 10:13pm UTC](https://community.cartalk.com/t/passing-gas/78376/3 "2013-03-31T22:13:00Z")
Don’t worry about it. Soon, it just won’t happen. > **[EPA rule would cut smog-causing sulfur in gas](https://www.usatoday.com/story/money/cars/2013/03/29/epa-sulfur-gas-new-rule/2032735/)** > > The Environmental Protection Agency plans to announce new rules today that will require lower-sulfur fuels, which will help reduce smog-causing emissions. Your gasoline will cost more, but it could be worse - you could live in Maryland, where gas taxes will increase from 4 cents a gallon next year then up to 20 cents per gallon when fully phased in. during 2016. That would about double the gas tax, which is now 23.5 cents. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [April 1, 2013, 12:52am UTC](https://community.cartalk.com/t/passing-gas/78376/4 "2013-04-01T00:52:43Z")
When cars are climbing a hill, the engine is programmed to run a little richer for extra power…Also the EGR valve is closed, also to produce more power…The catalytic converter has to work extra hard to clean up the fumes produced and therefore create the smell you sometimes notice…Sulfur in the fuel makes it that much worse… ---
**Author:** ![longprime](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@longprime](https://community.cartalk.com/u/longprime)\ **Post date:** [April 1, 2013, 6:18am UTC](https://community.cartalk.com/t/passing-gas/78376/5 "2013-04-01T06:18:44Z")
As many of you have stated, Gasoline can come from different sources and still be marketed under the same brand. So how does one know? Do I send wifey out to the tail end, and tell her to take a deep sniff? ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 1, 2013, 8:08pm UTC](https://community.cartalk.com/t/passing-gas/78376/6 "2013-04-01T20:08:30Z")
You cannot know. But to your benefit, the feds are promulgating regulations reducing the amount of sulpher allowed in gasoline. Of course, you’ll pay more at the pump. ---
**Author:** ![longprime](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@longprime](https://community.cartalk.com/u/longprime)\ **Post date:** [April 1, 2013, 8:45pm UTC](https://community.cartalk.com/t/passing-gas/78376/7 "2013-04-01T20:45:50Z")
A passing car had an exhaust smelling of burning metal, more acrid than acidic. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 1, 2013, 8:59pm UTC](https://community.cartalk.com/t/passing-gas/78376/8 "2013-04-01T20:59:51Z")
Assuming that this smell was different than the 'sulfurous" smeel mentioned in the original post, perhaps that car had a new exhaust system or cat converter and you were smelling the machining oils burning off. Or maybe it was a diesel converted to fryer grease and you were smelling last weeks fried onion rings. ---
**Author:** ![cwatkin](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@cwatkin](https://community.cartalk.com/u/cwatkin)\ **Post date:** [April 1, 2013, 9:34pm UTC](https://community.cartalk.com/t/passing-gas/78376/9 "2013-04-01T21:34:13Z")
Although I still do get a whiff of rotten eggs from other cars, it is nowhere near what I can remember 10-20 years ago. I am sure that engine management as well as cat converters have gotten a lot more precise over time and the fuels have had a reduction in sulfur which also helps. The “burning metal” smell you mention could have been related to a new car or some new car part with the machining oils/protective coatings burning off. It could also have been burning brakes or a burning clutch as these have an odd but distinctive burning odor. They kinda smell like burning rubber and metal combined and I think it is a very foul smell. You will definitely take note of this. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 1, 2013, 11:08pm UTC](https://community.cartalk.com/t/passing-gas/78376/10 "2013-04-01T23:08:17Z")
Make that 40 years ago. In the early '70s, when manufacturers were trying to adjust to the new emissions requirements, one of the first things they did was tweak the carbs to run the engines as lean as they possibly could. This elevated cylinder temps, like using a bellows in a fireplace. The carburated engines still had to run relatively large droplets of fuel, so we had unburned fuel with high cylinder temps. One of the byproducts was commonly sulpher hydroxide, that rotten egg smell. It was not at all uncommon. EGR systems came into being to try to control the spiking cylinder temps. Eventually, with the conversion to throttle body fuel injection, they were able to burn less fuel and controlling the cylinders with EGR systems, the problem pretty much disappeared. ---
**Author:** ![longprime](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@longprime](https://community.cartalk.com/u/longprime)\ **Post date:** [April 2, 2013, 12:06am UTC](https://community.cartalk.com/t/passing-gas/78376/11 "2013-04-02T00:06:06Z")
Burning clutch seems plausibe for the acrid smell since we going hill and passing car of course had to have more torque on the clutch. BTW, besides the clams, I had discounted the two farting crabs since they were in stupor mode (on their backs). ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 2, 2013, 12:27am UTC](https://community.cartalk.com/t/passing-gas/78376/12 "2013-04-02T00:27:09Z")
Crabs? I thought you were chasing clams? ---
**Author:** ![longprime](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@longprime](https://community.cartalk.com/u/longprime)\ **Post date:** [April 2, 2013, 3:00am UTC](https://community.cartalk.com/t/passing-gas/78376/13 "2013-04-02T03:00:28Z")
I chased clams.I got a phone call from wifey that son wanted fresh crab and fish. Bought the crabs and seabass. I was lucky on all the seafood because the weather was beautiful, and the fisherman had corraled some big crabs and roped some large seabass. Doubly lucky in that he wasn’t presold out on end of SpringBreak-Easter.