Hi everybody, for a while I have been trying to track down this rotten egg smell I notice sometimes when I drive my car. When my car was a A4 I only notice the smell when I floored the car and when I got to a stop light, the smell would araise. When I converted my car over to a M6 I notice it when I cruise at high rpms and when I get to a stop the smell araises. So today I decided to get my cat replaced with a new one that I bought. The converter I bought was a carsound cat. I though it would fix the problem but apparently the smell is still there. Also last week I replaced my spark plugs. The plugs look good, no signs of the car running rich. So now I am out of ideas. I had a buddy scan my car, and he was not able to see anything wrong. My car use to be a dual cat but I converted over to a single cat. Would programming be required for this? Also my friend loaded up a M6 file after the T56 swap. The O2s have been replaced. Would a bad EGR cause this or a bad fuel injector? Or would I have to change out my opti? Any help would be apprecaited. Thank you in advance for your time and help.

 

you check under your back seat for a dozen lost easter eggs? Actually if you are smelling something like that it means you got an exhaust leak somewhere getting into the car. OR you really have rotten eggs somewhere.
....Is it more like rotten eggs or bad feet?

 

sounds like a clogged cat, time for a ORP

 

Sometimes is the grade of gas used. Do you use the same brand of gas everytime. Different brands of gas have different sulfur contents which is what you are smelling. Try changing brands and may go away.

 

Used to be a service manager at a Mitsubishi dealership and had customers complain of rotton egg smell from exhaust after car was driven hard, we used to tell them it was normal, or if they kept complaining of it we would replace the cat converter for them with converter that had a higher nickle content. My Z28 had a cheap crap converter on it for a year and always had the rotton egg smell then the internals started rattling so I had it replaced with a Walker high flow, no more smell noticed. From my experience depending on the converter the smell is normal and converter working properly.

 

keep in mind..its important to change your underwear ATLEAST once a month..if not..there are unfair blames towards innocent Z's!

 

I just replaced the cat yesterday with a brand new carsound cat. I usually use the same gas station and always put the highest grade of octane which here in california is 91 . I have also tried a different brand of gas and the problem is still there. Should I check the EGR valve?

 

If the egr was going bad, you'd have some stumbling problems. I've never heard an egr do this anyhow.

 

Rotten Egg usually = A cat that needs gutting!!!

 

a rich condition with sometimes cause a rotten egg smell