Strong exhaust fumes smell SOLVED
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- 635sharknose
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Strong exhaust fumes smell SOLVED
My car is driving very well, but I start to bother with the rather strong exhaust fumes that always hangs around the car when I have driven it. You can smell the fumes everywhere around the car. The car does not smoke (no blue, black or white smoke).
Sometimes it is more than other times, but you always smell it after a drive. It does smell burned, not like petrol.
The car also bucks/jerks a bit at low rpm’s, perhaps this has something to do with the smell too. I think something is wrong with the injectors or the air/petrol supply.
Engine block leaks slightly but not much (about a drop per week), so it is not that a lot of oil leaks on the exhaust.
My car was originally fitted with a catalytic converter, I took it off a while ago and it turned out to be completely empty, I’m not sure if that could perhaps cause the strong smell of exhaust fumes.
Someone a good idea what I can look at best?
Sometimes it is more than other times, but you always smell it after a drive. It does smell burned, not like petrol.
The car also bucks/jerks a bit at low rpm’s, perhaps this has something to do with the smell too. I think something is wrong with the injectors or the air/petrol supply.
Engine block leaks slightly but not much (about a drop per week), so it is not that a lot of oil leaks on the exhaust.
My car was originally fitted with a catalytic converter, I took it off a while ago and it turned out to be completely empty, I’m not sure if that could perhaps cause the strong smell of exhaust fumes.
Someone a good idea what I can look at best?
Last edited by 635sharknose on Wed May 05, 2021 7:44 am, edited 1 time in total.
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
- hornhospital
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Re: Strong exhaust fumes smell
You found it. That lack of a catalytic converter is the cause. Partially burned hydrocarbons because there's no catalyst to complete the combustion.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
Re: Strong exhaust fumes smell
But many/most 6ers supplied into the European market didn't have a cat, but I would never have said I've found exhaust smells to be especially noticeable.hornhospital wrote: ↑Mon Jul 27, 2020 9:39 am You found it. That lack of a catalytic converter is the cause. Partially burned hydrocarbons because there's no catalyst to complete the combustion.
Paul - have you checked the exhaust gasket? That's about the only think my car has ever needed in terms of anything related to the engine.
Phil
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1988 Highline 635 CSi
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- hornhospital
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Re: Strong exhaust fumes smell
Yours was designed and tuned to run a catalytic converter, the Euro models weren't.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
- 635sharknose
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Re: Strong exhaust fumes smell
Thanks for your comments guys!
I think it would be a good idea to give it a try with a new catalytic converter. Also because of the fact that the car now emits much more than necessary.
There is now a Magnaflow under my car (see photo below), as mentioned, it is completely empty.
The same model is still available, MagnaFlow Universal Federal Catalytic Converter 94007.
Do you guys perhaps have a better alternative than the Magnaflow?
My car is from California, I see that there are other (CARB) catalysts to be mounted in that state. However, it is unclear to me what the difference is. I assume that a “federal” catalyst also works, right?
I think it would be a good idea to give it a try with a new catalytic converter. Also because of the fact that the car now emits much more than necessary.
There is now a Magnaflow under my car (see photo below), as mentioned, it is completely empty.
The same model is still available, MagnaFlow Universal Federal Catalytic Converter 94007.
Do you guys perhaps have a better alternative than the Magnaflow?
My car is from California, I see that there are other (CARB) catalysts to be mounted in that state. However, it is unclear to me what the difference is. I assume that a “federal” catalyst also works, right?
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Re: Strong exhaust fumes smell
Clearly that's true, but does that also imply that the ecu mapping is different to suit both versions? And if so, can the ecu be re-mapped?hornhospital wrote: ↑Mon Jul 27, 2020 2:44 pm Yours was designed and tuned to run a catalytic converter, the Euro models weren't.
Last edited by plip1953 on Tue Jul 28, 2020 10:26 am, edited 1 time in total.
Phil
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Re: Strong exhaust fumes smell
"The car also bucks/jerks a bit at low rpm’s"
This statement plus strong smell leads me to think it's running rich.
This statement plus strong smell leads me to think it's running rich.
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
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- 635sharknose
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Re: Strong exhaust fumes smell
Thanks for your response Bob!
I just found that a catalytic converter could break due to a car running rich. That may have been the reason why my catalytic converter broke. It was not completely empty, there was still a loose piece (see photo). To me it shows that a large part of the catalyst has melted down. As I understand now, this may be due to a too rich a mixture.
What is the best method to look for the cause of the rich mixture with the M30 engine?
I just found that a catalytic converter could break due to a car running rich. That may have been the reason why my catalytic converter broke. It was not completely empty, there was still a loose piece (see photo). To me it shows that a large part of the catalyst has melted down. As I understand now, this may be due to a too rich a mixture.
What is the best method to look for the cause of the rich mixture with the M30 engine?
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Re: Strong exhaust fumes smell
Presumably a cat equipped car has a lambda sensor (whereas non-cat cars of the era, like my own, did not)?
That's where I would first be looking ie is the lambda sensor still connected and/or in good working order. Otherwise I guess I might be thinking it could be a faulty airflow meter.
That's where I would first be looking ie is the lambda sensor still connected and/or in good working order. Otherwise I guess I might be thinking it could be a faulty airflow meter.
Phil
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Re: Strong exhaust fumes smell
Not a bad idea Phil.
I am sure the lambda sensor is connected. But I'm not sure if it works.
I will take it out an try to test it, same with the air flow meter.
Thanks for the tips!
I am sure the lambda sensor is connected. But I'm not sure if it works.
I will take it out an try to test it, same with the air flow meter.
Thanks for the tips!
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
- 635sharknose
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Re: Strong exhaust fumes smell
I want to buy a new lambda sensor.
Does anybody know which brand is most suitable to buy?
OEM is € 180,00
There are many alternatives, starting at € 25,00 to € 125,00
Many brands (Bosch, Magneti Marelli, NGK and a lot of unknown brands)
Does anybody know which brand is most suitable to buy?
OEM is € 180,00
There are many alternatives, starting at € 25,00 to € 125,00
Many brands (Bosch, Magneti Marelli, NGK and a lot of unknown brands)
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
- hornhospital
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Re: Strong exhaust fumes smell
Personal preference here, but I've had others with the same experience. Bosch only. The rest may work for a while, or not at all.
And that is no doubt the cause of the rich smell. The Motronic system (and almost all others) default to full rich if the O2 sensor fails. My Jeep Grand Cherokee is doing that right now. Scan it and it says the O2 sensor cannot read the exhaust gasses, and it smells rich (and get HORRIBLE gas mileage).
And that is no doubt the cause of the rich smell. The Motronic system (and almost all others) default to full rich if the O2 sensor fails. My Jeep Grand Cherokee is doing that right now. Scan it and it says the O2 sensor cannot read the exhaust gasses, and it smells rich (and get HORRIBLE gas mileage).
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
- 635sharknose
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Re: Strong exhaust fumes smell
Thanks! Then that is what I will buy.
I must say I had a strong preference towards Bosch already.
Yes, that is most likely what is happening to my car as well! Hope it solves the issue.
That and a new cat.
Thanks
I must say I had a strong preference towards Bosch already.
Yes, that is most likely what is happening to my car as well! Hope it solves the issue.
That and a new cat.
Thanks
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
- 635sharknose
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Re: Strong exhaust fumes smell
The smell is gone!
I exchanged:
- catalytic converter (actually the complete exhaust)
- oxygen sensor
- oil dipstick seals
One of these was causing the smell, which one I'm not sure as I replaced it all at once.
I exchanged:
- catalytic converter (actually the complete exhaust)
- oxygen sensor
- oil dipstick seals
One of these was causing the smell, which one I'm not sure as I replaced it all at once.
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Re: Strong exhaust fumes smell SOLVED
Was definitely the Cat.
I don't have my cat and my car smelled strongly until I went through the effort of eliminating all exhaust leaks.
Still smells, but at least I don't after driving it.
I don't have my cat and my car smelled strongly until I went through the effort of eliminating all exhaust leaks.
Still smells, but at least I don't after driving it.
SHRKATK - Red 87' 635csi
- 635sharknose
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Re: Strong exhaust fumes smell SOLVED
Yes, I do recognize that.
I installed a cat of a E32, perhaps that can be an option for you too.
https://bigcoupe.com/phpBB2/viewtopic.php?f=2&t=31538
I installed a cat of a E32, perhaps that can be an option for you too.
https://bigcoupe.com/phpBB2/viewtopic.php?f=2&t=31538
Paul
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Instagram: @635sharknose
1987 635CSi Bronzitbeige
Re: Strong exhaust fumes smell SOLVED
I actually chopped mine and the resonator to get a bit more clearance. my driveway is weird and my car was high centering.
No problems now and no emissions in my state to worry about.
No problems now and no emissions in my state to worry about.
SHRKATK - Red 87' 635csi