jumpy idle and rotten egg smell

[cheaploopjob]

I don't know if they could be related but the car has a idle that fluctuate slightly once in a while and as time has past is getting more and more noticeable. I counted 5-10 times in about a minute... and the rpm doesn't go up or down but sounded like a misfire/shutter or something. It happens no matter when its cold start or after I drove the car for 45 minutes.

There are no other sounds that I can hear that's not right and there are sometimes rotten egg smell when I got out of my car.

Could it be the spark plugs? the idle control valve? o2 sensors? cat?
:help

[Patrón]

I just posted a similar post just a few seconds ago. My rpms don't jump around, but it sounds like my exhausts farts or has a slight backfire @ idle every few seconds. Car runs great though but it would be nice to fix it if it is a problem and the car runs better.

[JClark]

My car has done the fart thing in the past before and over the course of replacing o2 sensor and a couple other little things it went away (so far at least). I dont know what pinpointed it. Plugs didnt fix it. Find out what your due for on your maintenance list and give it a try. The rotten eggs smell is your cats after working hard.

[OxfordM3]

I was told that the rotten egg smell is friom the cats going bad, despite this i still managed to pass the environmental test for the past 4 years without replacing them.

[JClark]

The only way your cats can go "bad" is if they leak or break internally. I've been told the rotten egg smell is fumes that the cat couldnt burn fast enough.

[ParadigmGuy]

Rotten egg smell = Melted cats

[Serious]

sounds like catlysts.

[GRAY GOOSE]

Smell = http://www.billeberga.com/kattutst/arunas/slapia%20kate.JPG 'S

In other words your cats have gone bad.

[Bernanke]

smell is cats, they can go back (takes roughly 8-10 years, which most of our cars are approaching that). The idle is dirty Idle control valve and throttle body. clean the throttle body first it should help out a bit, use TEFLON SAFE throttle body cleaner, some are not teflon safe and damage the teflon coatings on our throttle bodies. idle control valve can be cleaned without taking it out but if you want rock steady idle you will need to remove it and do a full cleaning which is what I am gonna do as soon as i do throttle body install.

[uber e36]

can the fluctuating idle be a vacuum leak? someone told me this...

[Bernanke]

can the fluctuating idle be a vacuum leak? someone told me this...


yes it can be, our cars are notorious for air leaks and crappy idle. usually cleaning idle control valve and throttle body cure 90% of the problem, sometimes the problem is ECU based in very few cases. Also an old cracked rubber throttle body elbow boot can have microscopic cracks in it that allow air to leak in, i replaced that as well for like $10 i believe it was. well worth it.

[cheaploopjob]

I just want to update this thread about my problem which has been solved.
I install the hfm kit(24#/TMS chip/540 HFM) and a bigger TB this weekend...
not only did I gain some good power but the idle is wayyyy smooth, even
better than when I got the car a year ago.. its idle like its brand new car or something
I highly recommend this setup... Peace out

[ParadigmGuy]

You sure the smell is gone? I wonder what it was if it wasn't the cat.

[cheaploopjob]

oh the smell is still there... its the rough idle that had been solved...
I am gonna have somebody to do a custom trackpipe hopefully later next month

[95MMM]

smell is cats, they can go back (takes roughly 8-10 years, which most of our cars are approaching that). The idle is dirty Idle control valve and throttle body. clean the throttle body first it should help out a bit, use TEFLON SAFE throttle body cleaner, some are not teflon safe and damage the teflon coatings on our throttle bodies. idle control valve can be cleaned without taking it out but if you want rock steady idle you will need to remove it and do a full cleaning which is what I am gonna do as soon as i do throttle body install.


you can clean the IACV without removing it? please explain

[Bernanke]

do it hte right way, remove it

[ParadigmGuy]

oh the smell is still there... its the rough idle that had been solved...
I am gonna have somebody to do a custom trackpipe hopefully later next month
Ahh, OK. The smell is the melted catalytic converter.

[RRSperry]

The smell is not a melted cat. The smell is the cat doing it's job. The gas he is getting has a high sulfer content. High heat in the cat and a high sulfer fuel = rotten egg smell.

[DLO]

The smell is not a melted cat. The smell is the cat doing it's job. The gas he is getting has a high sulfer content. High heat in the cat and a high sulfer fuel = rotten egg smell.


This is something i STILL do not understand. So your telling me our cars smelled like Sh*t from the factory? Mine will give off the nasty rotten egg smell when i first take it through the powerband or if i'm just pushin the car real hard. So how can we understand what is actually going on? Is this a problem or not? I'd like to get rid of the smell personally, but if nothing's wrong with the car. .. . :confused

D

[95MMM]

do it hte right way, remove it

i have tried to get at it, but the intake manifold is in the way

i really do not want to remove the intake manifold.

is there a temporary, easy way to clean it?

[RRSperry]

This is something i STILL do not understand. So your telling me our cars smelled like Sh*t from the factory? Mine will give off the nasty rotten egg smell when i first take it through the powerband or if i'm just pushin the car real hard. So how can we understand what is actually going on? Is this a problem or not? I'd like to get rid of the smell personally, but if nothing's wrong with the car. .. . :confused

D
No it's not a problem, and it didn't come from the factory that way. It's a function of sulfur in the gas. In the USA we have a high sulfur content, compared to the EU. Ever hear of the Nikasil V8 engine block?

The smell is normal given the makeup of most fungible (commingled) gasoline sold today. The sulfur content changes depending on the batch of crude, the refinery where produced. Try Amoco Ultimate, or Sunoco 94 if available. They are unique products. (non-fungible)

[DLO]

No it's not a problem, and it didn't come from the factory that way. It's a function of sulfur in the gas. In the USA we have a high sulfur content, compared to the EU. Ever hear of the Nikasil V8 engine block?

The smell is normal given the makeup of most fungible (commingled) gasoline sold today. The sulfur content changes depending on the batch of crude, the refinery where produced. Try Amoco Ultimate, or Sunoco 94 if available. They are unique products. (non-fungible)


See, funny you should mention that because i ONLY put Sunoco 94 in my car and still have the nasty hull. Guess i should just produce my own fuel. .. :(

D

[95M3CSL]

No it's not a problem, and it didn't come from the factory that way. It's a function of sulfur in the gas. In the USA we have a high sulfur content, compared to the EU. Ever hear of the Nikasil V8 engine block?

The smell is normal given the makeup of most fungible (commingled) gasoline sold today. The sulfur content changes depending on the batch of crude, the refinery where produced. Try Amoco Ultimate, or Sunoco 94 if available. They are unique products. (non-fungible)

My 95 doesn't smell if I am lightly on the gas and park in my garage. When I'm hard on the gas getting home and park in the garage I get the sulfur smell. It has been that way for a while and my car has passed CA emissions 3 times in the past 5 years with no problems at all. I've also got JimC CAI with Euro HFM and software that goes with it. I'm in SoCal, change oil once per year, and track the car too a few times a year.

I consider the occasional idle miss when at a stoplight (once every 10 seconds or so) and the sulfur smell to be normal. I almost exclusively use the local Chevron 91 octane here.

Regards,
Marc
95M3
LA
sulfur smelly.

[teasley]

i was wondering if anybody has had a custom track pipe made and how much did it gain them. i have a 95 m3 so the turner or AA pipes which are the same i guess seem like a good idea to me. i was just wondering if someone has had one made and if they got the same gains and for how much $.

[ParadigmGuy]

This is something i STILL do not understand. So your telling me our cars smelled like Sh*t from the factory? Mine will give off the nasty rotten egg smell when i first take it through the powerband or if i'm just pushin the car real hard. So how can we understand what is actually going on? Is this a problem or not? I'd like to get rid of the smell personally, but if nothing's wrong with the car. .. . :confused

D
You don't understand what he's saying because it doesn't make sense. The smell is a bad cat.