I'm not sure exactly what circumstances it takes to make it happen, but when I push my car hard, to say 110 mph, momentarily after I slow down my car is filled with a rotten egg smell. The stench only lasts for about a minute, but it makes me very hesitant to drive my car fast because I don't know what that smell is. For all I know something under the hood is melting. I already have a trip to the dealer set up in about 20 days. Should I bring this issue up, or is it just a normal thing that happens and goes away?

 

Driving your car that Fast, maybe you should check your underware.

 

Catalyst convertor will make that smell after hard driving .

 

Cat shouldn't make that smell, ever, and it should never get in the passenger compartment. Have the dealer check for exhaust leaks when you do your service.

 

Rotten egg smell is usually associated with sulfur. Sulfur does compete with oxygen for active sites on the catalytic converter. That is why some PZEV vehicles recommend BP or low sulfur fuel, and why CA is all low sulfur fuel. My guess is at that speed (and resultant exhaust flow rate) the catalytic converter will get quite hot. Under those conditions it may be expelling larger amounts of sulfur compounds than under normal conditions.

I have gotten rotten egg smell out of my Honda Accord, and I know that to be the reason. Many cars will have a slight sulfur smell. This smell will eventually decrease with age of the car and break in of the catalytic converter. It has in my accord. Emissions is fine.

The smell will usually be worst on cold start up, or hard acceleration. Sulfur amounts vary state to state, but you could try BP. Another thing to try would be to not drive 110 mph.

 

Well put glangford . I did not have time to go into detail as you did . I have worked in the service department for dealerships for 31 years . I see this very thing everyday from cats . Normal .

 

Read your post again. The momentarily after slowing down from 110 mph is a strong indication of a hot catalytic converter and the catalyst dumping excess sulfur. If your window is down you probably can smell it. It takes very little sulfur to actually smell, if you've ever lived near a paper mill and smelled thionyl chloride, you'd know. Shouldn't be a concern, other than perhaps driving habits. If your windows are up when you slow down, then I would take the previous recommendation and look for exhaust leaks into the cabin. There sulfur is not the problem, but odorless carbon monoxide.

 

Some of my Ford 4.6L's did the rotten egg cat smell when the valve stem seals were worn and oil was getting past too...

Has anybody else gotten the burnt cat (not cat-con; I mean kitty-cat) smell after a hard run at altitudes over 3000 feet? I get it on an easy run at very high (over 9000 feet) and harder runs at lower elevation. Dealer can't duplicate, of course...

 

 

Gabe,

No more egg salad sandwiches for you.

Sounds like the Cat has a little too much unburned fuel in it when you abruptly lift the throttle at speed.

 

I have smelled this as well from my 2007 MCS. Unfortunately, not after going 110. I notice it sometimes after rapid acceleration / deceleration when in town. Hard driving always precedes the stench.

 

I have also had this smell after going up and over 100mph. But goes away within 20 seconds, I feel better I thought it was my clutch burning somehow.