wtf my exhaust smells like slufer or rotten eggs.

[speed3codes]

lately ive been smelling sulfer and rotten egg smell from my exhaust i usually pump the same shit bp 93 so idk wth it is?
07 ms3 80k on it.

[Ferdball]

bad cats?

[speed3codes]

how do i check if they are bad?

[mrtheandrew]

Bacon cooks well also. Havent tried eggs myself.

[Spec]

If they look like this, then they're bad.

[speed3codes]

lol that is a very mean cat. my cat looks almost as bad

[bcmountainspeed]

Good time to go catless..

[speed3codes]

yeah i have been thinking about going that route, just dont have cash for it. i still need to buy a rmm.

[bcmountainspeed]

I don't think the smell is gonna get better

[atvfreek]

You have a CAI, have you gone through any hard rain lately. If the maf gets wet, or dirty, it causes the engine to run poorly and the Cat's have to work overtime to clean the exhaust. And that will cause that smell.

[Agent_Orange]

My exhaust smells like rainbows & Unicorn farts.

[Lex]

Is this only when you first drive the car? After a hard drive?

If you are running richer or the fuel mixture at the pump has changed it can cause these kind of smells.

Has the performance or spool changed at all?

[speed3codes]

I Havant felt any performance difference but it has rained hard here lately Nc so it rains almost everyday.
So if I clean the maf and its housing pretty well that may help out?
And its like this when I first start driving and either stays the same after a short drive or gets slightly better but always smells bad during then first time I drive it. I do have a cai and I wanna trade it out for a sri
I just dont have my stock air box to put in while I post my cai for trade.

[Lex]

Before taking apart the exhaust, clean/dry the MAF (do not touch the 2 recessed resistors) and see if this still happens.

[speed3codes]

I'll do it tomorrow during my lunch break. And if anyone doesn't want their stock air box I could use one......

[Teejhorse]

get a new feline

[I_Heart_Haters]

You should sell the turbo timer and get a RMM. You're welcome.

[speed3codes]

Cleaned my maf sensor today with some cleaner I picked up
Car did seem to idle better and drive smoother, will check the smell when I drive home from work today.



*edit*
still smells like the eggs.

[Teejhorse]

Originally Posted by speed3codes Cleaned my maf sensor today with some cleaner I picked up Car did seem to idle better and drive smoother, will check the smell when I drive home from work today. *edit* still smells like the eggs.

are you getting a check engine light? When I had the rotten egg smell it was due to my catalytic converter going out. I was getting the error code "catalyst efficiency below threshold". You might need a new cat in the future, I would recommend a tabby or a callicoat.

[speed3codes]

I don't have a check engine light. And I'll look into those cats man.

[dark_speed89]

From what I know that smell doesnt mean your cats are bad. The smell comes from using gas with high amounts of sulfur. When this gas is burned there is a chemical reaction with the cats which lets off the rotten egg smell. If everything is running as it should dont worry about it. But if you want to get rid of it change what gas your running or better yet, go catless!

[KusteLokal]

Your cats are in the way out. You'll get a cel eventually once they die. Just keep driving.

Tappin from S3

[speed3codes]

Originally Posted by KusteLokal Your cats are in the way out. You'll get a cel eventually once they die. Just keep driving. Tappin from S3

i did get better gas milage by cleaning the maf, and i guess ill just drive them till they die and go catless. by then i should have enough cash for some exhaust parts.

[Owtlaw333]

Bumping this because it’s relevent to me right now...

I’ve been getting a “rich at idle” code that won’t go away and my exhaust smells of sulfur. I have yet to get a “catalyst” code though. I’ve already had the oxygen sensor replace and the MAF sensor cleaned and still have the issue. I do have a CS SRI and TMI, but I’ve had those for a number of years before ever having this issue.

I’ve been suspecting bad cats but the shop is suggesting checking the wiring to the sensors and ECU and wanting $250 to do so... should I have them inspect those, or should I just have the cats replaced?

Any advice would be greatly appreciated!!

[neganox]

Your cats are on the way out because you're running rich. Do you have a boost leak somewhere? Perhaps the intercooler couplers.

[Owtlaw333]

Originally Posted by neganox Your cats are on the way out because you're running rich. Do you have a boost leak somewhere? Perhaps the intercooler couplers.

Coupler is definitely ok. I can’t say for certain I don’t have a leak though (haven’t had it physically tested), but I’ve never shown any dips on the AP either.

[neganox]

Originally Posted by Owtlaw333 Coupler is definitely ok. I can’t say for certain I don’t have a leak though (haven’t had it physically tested), but I’ve never shown any dips on the AP either.

Unless it's an exploded coupler, you wont see it.

Dips in what?

What is your LTFT at idle?

[Owtlaw333]

Originally Posted by neganox Unless it's an exploded coupler, you wont see it. Dips in what? What is your LTFT at idle?

After reading that back, I have no idea what I meant, haha. Sorry. I think I meant I hold boost as normal, but I've never had a pressure test done.

At idle I sit at -0.2 and -20.4 at load... so a bit off.

[Fstrnyou]

Rich at load...boost leak.

[Owtlaw333]

Originally Posted by Fstrnyou Rich at load...boost leak.

Would that account for idle as well? Rich at idle has been an issue for some time, whereas at load is new (code-wise.)

[Pu Manchu]

Originally Posted by Owtlaw333 Would that account for . . .

check this Understanding Fuel Trims & Using Them To Detect Leaks

[mituc]

The STFTs go crazy in open loop, so you need to look at the commanded and actual AFR to determine if it's rich or not.

If the exhaust smells like rotten eggs most probably your cats are shot. There is no problem (having the smell as a symptom) with your car. If the car ran rich the exhaust smell was pure gas.

[Owtlaw333]

Originally Posted by Pu Manchu check this Understanding Fuel Trims & Using Them To Detect Leaks

Awesome. I’m out of town at the moment, but I’ll take a look at this when I get back. I appreciate it!

[mituc]

Check your tyre pressure as well, because that is as likely to contribute to your issue as it's your closed loop fuel trims. Oh, and also wash the car.

[Owtlaw333]

Originally Posted by mituc Check your tyre pressure as well, because that is as likely to contribute to your issue as it's your closed loop fuel trims. Oh, and also wash the car.

Car washed... still having issues


So, ran a couple logs as best I could tonight (a mostly warmed idle for reference and 3rd gear pull on a not-so-smooth on-ramp)... Gunna try to check things over this week and hopefully pinpoint something. Read through the linked thread and everyone seems to be all over the place.

Thanks for all the help so far!

[mituc]

3rd gear WOT log looks fine, the idle log doesn't. The AFRs at idle are around 13.1-13.2 and they should be somewhere between 14.5 and 14.8 depending on various things, or steady at 14.7 with no AC, heating, and a warm engine.

So 3rd gear kind of confirms the primary O2 is fine, the idle log may show a vacuum leak. Or the MAF cal is not right in that area, but as the STFTs tell the deviation is more than 25% from target. Also, you never told us what mods are on the car, mostly the intake is important here.

[Owtlaw333]

Originally Posted by mituc 3rd gear WOT log looks fine, the idle log doesn't. The AFRs at idle are around 13.1-13.2 and they should be somewhere between 14.5 and 14.8 depending on various things, or steady at 14.7 with no AC, heating, and a warm engine. So 3rd gear kind of confirms the primary O2 is fine, the idle log may show a vacuum leak. Or the MAF cal is not right in that area, but as the STFTs tell the deviation is more than 25% from target. Also, you never told us what mods are on the car, mostly the intake is important here.

As far as mods, I think my signature is up to date... Upgraded HPFP, CS TMI, SRI, TIP and intake box. I’ve run two different spark plugs with the same results (standard and one step cooler... log is with standard), primary o2 sensor is now brand new, MAF sensor has been cleaned and checked. And running tuned or stock maps also yield basically the same results.

Let me know if I missed anything. And thanks again!

[mituc]

Would you mind sharing your MAF cal table? Attach the file here as a .csv file (coma separated).

[Owtlaw333]

Originally Posted by mituc Would you mind sharing your MAF cal table? Attach the file here as a .csv file (coma separated).

It's been years since I've accessed any of this stuff so maybe I'm missing something, but I had to dig for my copy of Accesstuner, got it installed, tried to load the map I used in that log and it's telling me it can't be opened "Invalid base map" Even updated the software. But again, even with running stock I still get rich at idle (same -25%)

Definitely not getting around to toying around with anything this week though... will have to revisit after the weekend

[mituc]

Ok, just to be sure check your oil level too and see if it's not way above max.