GM 5.3 rough idle & smelly exhaust.

95Trooper

Well-Known Member
Joined
Mar 23, 2008
Location
WNC
Just purchased a very clean one owner 2006 Yukon XL with 108k original miles on it. It runs out great. Has a small “misfire” at idle (you can pop the hood and watch the engine shake). You can really tell looking at the intake cover. Has a very bad rotten egg smell coming from the exhaust as well. Does not hesitate or sputter at all while driving. At WOT the cab Will fill up with the smell and choke you out! There are NO codes at all. I thought maybe the cats were clogged up, but a buddy mentioned that a misfire will make the cats stink bad. Anyone else experienced this?
 
Figure out the misfire, then drive the hell out of it, and see how it smells after that. If it's put any raw gas in the cat, that'll take them out pretty quick.
 
Feel the exhaust as it comes out of the tip. If it's really hot then your cats are clogged or are getting clogged.
 
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