rotten eggs and gunowder??

Numerous previous threads about engine performance problems refer to exhaust smelling like either rotten eggs or gunpowder. SO -- what do each of these two odors signify? I know, the question stinks but I'm looking for some refreshing replies.

Many engines smell like rotten eggs / sulfur at times...and run just fine the rest of the time...this often is normal...and an indication that the fuel mixture is not burning completely...

Now, the gunpowder smell...I have found in the 4.3 V6 Wseries...indicates...a fuel leak in the inside of the intake...Plenium do you have this engine...let us know?

the sulphur smell or rotten egg smell is usually the catalytic converter, especially stinky when really hot.