sulphur/rotten eggs smell from exhaust

[harriman]

Hey all,
So today I was driving my car and I briefly smelled rotten egg exhaust. I recently just changed the oil, oil filter, air filter, spark plugs, fuel filter, and belts. Last year I replaced the CAT, both 02 sensors, mass air flow sensor, drive shaft bearing, idle control valve, and guido (spelling).

I'm thinking that this smell is due to a batch of bad gas I picked up at some no name gas station. Also when I'm under heavy load going up hill in second or third gear I can hear this kinda of whining sound.. something new.. since this new batch of gas. I opened up the hood and located the sound to a black roundish thing attached to the intake manifold (big metal thing that has BMW stamped into the top).

I'm crossing my fingers that it was just a bad tank of gas. Any ideas

Thanks again

-Harrison

[cooljess76]

I've heard of cats smelling like rotten eggs when they're going bad, however it could just be that you got ahold of some funky gas. As for the whining sound, it sounds like you're describing the secondary air pump. It's a black plastic pancake shaped thing that has a hose going to the airbox and another hard plastic line that goes to the secondary air check valve on the front passenger side of the engine compartment. The secondary air pump only comes on for the first 30 seconds or so during cold startups. This pump is held together by six aluminum rivets that are known to break and cause the pump to leak. You'll need to check it in the morning when you first start the car. Have the hood popped and as soon as you start the car, run around and feel around the secondaray air pump. If you feel any air blowing out of it, you probably have broken rivets. I rebuilt mine using bolts/nuts and it worked just fine. The fact that you're hearing it when the car is under load bothers me though. As I mentioned before, it only comes on for the first 30 seconds, so if you're hearing it while you're driving, it's either something else or your secondary air check valve is bad also. FWIW, the secondary air system is directly related to the catalytic converter. The system is designed to blow clean filtered air into the exhaust stream while the evap system purges the fuel vapors that collect in the charcoal canister overnight while the car is sitting. The clean filtered air provided by the secondary air system compensates for the rich condition that is caused by the purging of the fuel vapors. A bad or removed secondary air pump or secondary air check valve can cause your cat to clog up and fail prematurely.

The secondary air pump isn't actually connected to the intake manifold though. The only black roundish thing that I know of that is connected to the intake manifold is called the crank case vent valve or CCV. This is a black disc shaped valve about the size of a silver dollar in diameter and is located on the back side of the intake manifold towards the firewall. When these go bad, they usually hiss, but I've seen/heard them make whining sounds before. The CCV usually breaks into pieces when you try to remove it. This is due to the plastic becoming brittle over several years. They cost about 50 or 60 bucks and when they go bad they hiss as mentioned and also have been known to cause a rough/irregular idle. So if yours isn't hissing and your car idles fine, just leave it alone.

It really sounds like you're referring to your secondary air pump though. I'd check that first thing in the morning if I were you. While you're in there, take a good look at the rubber intake boot going from the MAF to the intake manifold. This boot also becomes dry and often cracks/splits between the ribs. This causes all sorts of problems from rough idles to misfire codes. Anyway, hope this helps. Best of luck, let us know what you find.

-Jess

[3.2TI]

I hate that smell, knew a girl with a jetta who's car stank this way when I got near the car. I also heard that usually this means the car is bad but I am no expert on the TI one. Jess might the answer.

[harriman]

Thanks for the help Jess. After running two tanks of Chevron the problem and smell are gone. The car is running better then it was before the odd sounds/smell/ hesitation. Anyways thanks again. I guess there really is a difference between brands. I think I got the bad gas from ARCO AM/PM. From now on, I'm using Chevron.