sand_man

I've noticed a sulphur like smell coming from the exhaust...or so I think it's the exhaust.

Here's some background info: I have no muffler and/or CAT whatsoever...just a straight pipe exiting in the center. Whenever I go to work and park my car (in a parking garage) I notice the smell as I walk by the same area that I had just driven past...it sort of lingers. I always use the same Amoco/BP 93 octane fuel. I've also noticed that with a GP White car, there's a yellowish buildup on the underside of my tail section that takes a bit of elbow-grease to remove...I'm sure this has something to do with the exhaust exiting there.

I have about 5,000 miles on my new engine...still CIS. I use Shell Rotella "T" 15W-40 oil. Oil consumption hasn't been abnormal. The car has no smoke when it's driven and only the occasional smoke on start up.

From some searches that I've done, people have pointed to the smell being from a boiling battery, from overcharging, that is venting. I don't think that's it, but I'll check. Others have said to switch gas.

What do you guys think? I did borrow a leak-down tester from A930Rocket, but just haven't had a chance to use it yet. The car is running better than ever. My idle AFRs are at about 13.5:1 and dump down to about 11.5:1 on WOT full boost.

A930Rocket

Which reminds me...

I need to scan and send those instructions to you!

I'll do it tonight.

srf506

sand_man, You have a cat on that car? Usually sulpher is the smell they start giving off when they start to go bad.

911rudy

From my tormented days in chemistry class, I know that the sulfur smell is caused by sulfurdioxide. There are only two places on your car that can produce that chemical; battery and exhaust. If its your bat. it will be obvious because you will have severe venting and the associated crap that comes out of the battery when it is being over charged or over heating. If it is your exhaust it will take a little work. First try an octane booster and see if you can get a better burn percentage of the gasoline in your engine. If that dosen't work, try a different fuel supplier. Some companies ad several additives for different purposes, and your car without any exhaust devices, might not be burning them up in the CAT or the muf since you don't have either.

JasonAndreas

Exhaust System - Sulfur Like Smell

Group 2

Number 9604

Model All

Part Identifier 2673

July 11, 1996

Subject:
Sulfer-Like Smell from the Exhaust System

ATTENTION:
Service Manager / Service Technician

Concern:

Some customers may complain of a sulfur or rotten egg smell from the exhaust system.

General Information:

Sulfur found in gasoline is normally converted during combustion and catalytic after-treatment processes into sulfur dioxide (SO2). Under certain operating conditions, hydrogen sulfide (H2S) is formed instead of sulfur dioxide. To what extent this occurs depends largely on two factors: Sulfur content of the fuel and operating condition of the catalytic converter.

When the engine is running a rich mixture, such as under acceleration or under heavy load, there may be a relative lack of oxygen available in the catalytic converter to form sulfur dioxide. Hydrogen sulfide is formed instead. If there is an excess of sulfur in the fuel, more hydrogen sulfide is formed. It is the hydrogen sulfide which produces the sulfur or rotten egg smell. Hydrogen sulfide can be detected by the human nose at extremely low concentration levels, on the order of several parts per billion. Under normal operating conditions, hydrogen sulfide, is not formed at a level detectible by the customer.

If you have a customer complaint of a sulfur or rotten egg smell, you should do the following:

1. Check to make sure that there are no faults stored in the engine control module and that the engine and fuel systems are operating properly.

2. If there are no problems found with these systems, advise the customer to change to a different fuel brand. Since the sulfur content of available fuels can vary greatly, changing to a different brand of fuel with lower sulfur content should reduce the formation of hydrogen sulfide.


Please note that if there are no problems found in the engine or fuel systems, replacement of emission related components such as oxygen sensors or catalytic converters will not reduce the smell since the primary cause lies in the fuel. In this case, replacement of these or other emissions components will not be considered a warranty matter, and is strongly discouraged.

DeWolf

I often get that smell in the car when I take the unaquainted for a blast.

sand_man

Thanks for all the responses, guys! Keep them coming! Nope, no cat on my car. B&B headers and a 934 "zork" tube straight pipe. I've just filled up with fuel, so I think I'll burn this tank down (shouldn't be too hard) and then I'll re-fuel with a different brand.

And I promise the smell is not my upper lip or my own rear end! LOL! Well on second thought...

srf506

DeWolf, that ain't sulpher babe! ;-)

sand_man

I can't remember where I read it (might have been on Pelican), but I do remember one of the more experienced engine guys (Steve Weiner comes to mind) mention that the exhaust smell is more acrid and sulfuric on a new engine during break in. After about 5,000 miles I would have thought mine to be beyond this point. I dunno...maybe a dreamed the whole thing. Too much peoti maybe...

Win Rice

This is a long shot, but in the diesel truck world Rotella 'T' is know as ro-smella. It has a different aroma than the other diesel grade oils. I noticed this on my Dodge Cummins when I changed from Delvac to Rotella.

If you're burning a little oil still, this may be the culprit.

sand_man

What did you call me? JK! Anything is possible. I'm pretty sure that even before I made the switch to ro-smella, and was running Castrol GTX 20W-50, I remember the odor. I've got about 1/4 tank of fuel left and then I plan to switch. The only thing that's been totally constant is the Amoco/BP fuel...I've never run anything else in it since the new engine. We'll see...

kens911

yes might be the oil we switched to shell rotella in our emergency diesels because the new ultra low sulfur fuel lacked lubricity of regular low sulfur. So we switched oils to get some of it back the rotella might have a lot more sulfur in it