SL/R230: My SL pongs.....
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Joined: Oct 2002
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BMW 535d Touring
My SL pongs.....
I stopped to talk to some friends after a short trip to the beach this weekend - the smell of the catalytic converter was very strong and very embarassing...
A lot of explaining to do at the time - but the smell is getting worse and noticeable even while driving top down.
Do you think the CC is damaged or is this normal?
A lot of explaining to do at the time - but the smell is getting worse and noticeable even while driving top down.
Do you think the CC is damaged or is this normal?
Out Of Control!!
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I'm not really qualified to say anything, but I'll try anyway.
From what I've read on the forums does it smell like rotten eggs? If so it's HSO4 (oh i just finished chemistry 1!) Hydrosulfuric Acid, that goes and comes depending on if you've gotten a bad tank of gas and such. I'd say give it another tank or two and it should go away.
From what I've read on the forums does it smell like rotten eggs? If so it's HSO4 (oh i just finished chemistry 1!) Hydrosulfuric Acid, that goes and comes depending on if you've gotten a bad tank of gas and such. I'd say give it another tank or two and it should go away.
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From: UK
SL55 AMG
I've had new cars where there's a characteristic smell of bad eggs due to production of hydrogen sulphide (H2S), or sulfide as they would say in the US. Should go away once the cat settles in and is up to temperature, maybe the short trips to the beach and low speed posing are taking their toll Mustard 
Either that, or one too many vindaloos...
The real answer is that new catalysts are prone to produce H2S, here's why. During fuel rich driving (lots of accelerating and decelerating) hydrogen gas is produced in the exhaust by the water gas reaction. 3-way catalysts contain cerium dioxide which stores sulphur from the fuel under driving conditions - new cars are especially prone to produce sulphur; the capture forms cerium sulphate. Reduction of the cerium sulphate by hydrogen gas allows the formation of hydrogen sulphide. One potential solution is to include nickel in the catalytic converter; this reconverts the hydrogen sulphide back to hydrogen and sulphur.
Either that, or one too many vindaloos...The real answer is that new catalysts are prone to produce H2S, here's why. During fuel rich driving (lots of accelerating and decelerating) hydrogen gas is produced in the exhaust by the water gas reaction. 3-way catalysts contain cerium dioxide which stores sulphur from the fuel under driving conditions - new cars are especially prone to produce sulphur; the capture forms cerium sulphate. Reduction of the cerium sulphate by hydrogen gas allows the formation of hydrogen sulphide. One potential solution is to include nickel in the catalytic converter; this reconverts the hydrogen sulphide back to hydrogen and sulphur.
Last edited by blueSL; Jul 16, 2003 at 06:56 PM.
Thread Starter
Super Member
Joined: Oct 2002
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From: UK
BMW 535d Touring
Originally posted by blueSL
I've had new cars where there's a characteristic smell of bad eggs due to production of hydrogen sulphide (H2S), or sulfide as they would say in the US. Should go away once the cat settles in and is up to temperature, maybe the short trips to the beach and low speed posing are taking their toll Mustard Either that, or one too many vindaloos...
I've had new cars where there's a characteristic smell of bad eggs due to production of hydrogen sulphide (H2S), or sulfide as they would say in the US. Should go away once the cat settles in and is up to temperature, maybe the short trips to the beach and low speed posing are taking their toll Mustard
Either that, or one too many vindaloos... Can't eat curry, BlueSL !
The smell is very familiar - I lived near Rororua in NZ where naturally occuring Hydrogen Sulphides gave the whole area a rotten egg odour. I guess it will settle down, and I must say after the trip up from France its been a succession of short posing trips - so you are right, the cats probably never been up to temperature!
Good reason for a holiday....
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Joined: Oct 2002
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BMW 535d Touring
Originally posted by vraa
I'm not really qualified to say anything, but I'll try anyway.
From what I've read on the forums does it smell like rotten eggs? If so it's HSO4 (oh i just finished chemistry 1!) Hydrosulfuric Acid, that goes and comes depending on if you've gotten a bad tank of gas and such. I'd say give it another tank or two and it should go away.
I'm not really qualified to say anything, but I'll try anyway.
From what I've read on the forums does it smell like rotten eggs? If so it's HSO4 (oh i just finished chemistry 1!) Hydrosulfuric Acid, that goes and comes depending on if you've gotten a bad tank of gas and such. I'd say give it another tank or two and it should go away.
Wonder if its too high for the cat?
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SL55 AMG
The sulphur has to come from the petrol - nowhere else for it to come from, and I'm surprised because Optimax is decent stuff. A friend I studied engineering with at Cambridge works for Shell and is dead chuffed with what it does. I put it in each of my cars now after I saw some pretty convincing pictures of engine valves before and after using it and here in Gloucestershire, it's only about 5% more than regular unleaded.
