Hi all.  I'm actually posting on behalf of a friend who has had nothing
but problems with her '98 Accord EX V6 couple.  I'll try to stay on
topic and ask about only one problem this post, with more to follow
later most likely :P

Anyway, this car has under 100,000 miles on it (98,000 I believe) but
recently it has started to emit an odor that can best be described as
raw eggs.  The problem is that it's not constant.  I've personally only
smelled it once and the car was still relatively cold.  She has had it
smell other times when it hasn't started to smell until the engine was
warm for quite some time.  I smelled around the hood to see if I could
find out where the smell was coming from and after smelling around the
hood and then under the car, I determined it was coming from under the
front seats (underneath the car).  Now with the doors closed, this
smell cannot be detected but once you open either door, the smell is
awful.

I did some research and many mechanic websites said that it could be
the catalytic converter but she told me that this part was recently
replaced on her car.  After doing some more research, I saw that these
accords have a problem with their EGR system and I found out that this
system is somehow related to the exhaust system.

Could a clogged EGR valve (it's a valve, right?) be the cause of this
horrible, irregular smell?  Again, the most troublesome aspect of this
problem is that the smell is not consistent at all.  For example, we
drove her car all last night and didn't smell anything once.

Either way she's going to be taking it to a mechanic but I want her to
be prepared and be able to request the free EGR cleaning that she is
entitled to, if that is the problem.

Thanks!