I have an 02 SS with about 55000 on it. Sometimes when i get out it has a horrible smell that smells like rotten eggs. I recently had the cat changed so it is not that. Also when i am cruising and let off the gas, it takes sometimes 20 seconds for the tach to go back down, almost as if the throttle is stuck or something. Anyone have any ideas?

 

Misfire will give you that..Unburnt fuel from the misfire with burn in the cat, thus overheating it and destroying the materials inside, ruining it.. probably the reason why you changed a cat already?! Sounds like its time for at least a tune up... Check engine light on? if so get it checked for the code... Do it before you have to change the cat again because of another existing problem.. Cats on newer cars are designed to last at least 100k miles because of the gov't requirements on emmision warrantys...

 

The check engine light isn't on so how else would i be able to tell if it was misfiring?

 

Most reputable shops would be able to see if a misfire is happening with a scan tool.. but its an expensive proposition since then they are diagnosing a problem and usually charge for it.. the shop i work for charges 93 bucks just for the diagnosis ( an hour ) unless its a crazy situation that would require more time..And thats just to tell you whats wrong... then after that its up to the customer to approve further work..

Does it drive kinda rough at all? you would deffiantly know if it was having a misfire problem.. shakiness.. hard to accel? Might be slight in some cases and hasn't set off the light.. maybe just a pending code in the ECU.. which will not turn on the dash light until the ECU is certian there is a problem...

 

He could've had a faulty one, mine was. https://montecarloforum.com/m_12459/tm.htm

How long ago was it changed? After mine was changed it still smelled funny for a week or so.

 

The cat was changed about 2 weeks ago. There seems to be a little shakiness but i am unsure. It seems to have adequate power when you step on it but gas mileage has gone down a lot. If it is a problem with misfiring what would i need to do to fix the problem?

 

Sure sounds like a cat problem to me. I agree with the discussion about the tune up. At 55k, it shouldn't need one yet, but if cheap gas has been run thru it, it could have fouled plugs, clogged throttle body, and a host of other problems, along with the possibility of bad coil packs, however they will usually throw a CEL code from a misfire. Doesn't mean that they are weak tho. Ultilimately your smell IS your catalytic convertor giving you problems. It's letting you know something is wrong by the smell.
I had to replace my replacement cat on my '01 after only a few months. It broke.

 

If its beyond your skill to work on the car, its time to take it to a shop. If not then you can do this at home.. Plugs are easy and cheap to replace.. Wires probably aren't that bad, but look at them for problems ( like exposed wire, tears, etc ).. coils don't normally go out either.. So if i even had a hint of a misfire then go with the plugs 1st. Just go one at a time so you don't confuse firing order..

I just don't think a cat should die after just being put in, for no reason that is.. Though i think anything is possible, but not that likely.. they usually only have fits when something else is wrong.


You should also research something to the likes of SeaFoam.. just as a preventive maintenance in the future too.

 

Thanks for the advice. I am going to change the plugs tommorow and see if i cant get some seafoam and drop that in there.

 

Good luck and let us know if you find a fix!