Rotten egg smell, rough performance

rsrobbins · Post by **rsrobbins** » 05 Jul 2011, 11:18

Vehicle = 1999 C70 LPT 160,000 miles
Fillied up tank with Costoc premium.
Ran a couple of errands.
Came to a stop. Motor starting running rough. Felt like I was running on 4 cyclinders when I accelerated.
Started to smell rotten egg, sulfer smell like a bad cat.
From what I'm gathering on these boards suspects include:
Bad MAF (maybe cleaning will solve)
Bad 02 sensors
Bad coil pack(s)
But probably NOT the cat.
Do I have this right? Any other suggestions or misgivings about the above?
Thanks!
Ralph

Post by **jblackburn** » 05 Jul 2011, 11:40

READ THE CODE! And let us know what you find. Advance Auto, etc. will pull codes from the computer for free.

The OBDII port is in your center armrest.

Probably a bad coil causing a misfire. In the meantime, don't drive it too much or you'll risk damaging the cat. converter.

FCPEURO · Post by **FCPEURO** » 05 Jul 2011, 15:42

Rotten eggs normally means a clogged up cat. I would still pull the codes but more then likely, the cat will need to be replaced.

brady55 · Post by **brady55** » 05 Jul 2011, 18:37

also make sure your alternator is not over charging a battery that is being cooked smells like rotten eggs as well and they can go boom if too hot fyi

claymore850 · Post by **claymore850** » 05 Jul 2011, 19:10

Try changing the Catalitic converter...maybe its clogged... I replaced on my car years ago with a MAGNAFLOW 91006... no problems..cheap replacement part..

Post by **jblackburn** » 05 Jul 2011, 19:18

Check for codes before throwing money at a cat that is probably perfectly fine. A misfire sounds like all this is.

Raw gas through the cat from a non-functioning cylinder will cause the rotten egg smell.

Don't drive much before taking care of the coil pack if that is the issue. Running that hot and rich WILL burn up the converter.

rmv · Post by **rmv** » 05 Jul 2011, 20:59

Try to unplug the MAF sensor (electrical connection on airbox lid) and see if it will run better. Mine went unexpectedly.

Fishburn · Post by **Fishburn** » 05 Jul 2011, 22:58

This happened to me earlier this year on my 99 s70, it's probably a misfire, mine was caused by a bad ignition coil. I replaced all the plugs before I figured out it was the coil...

rsrobbins · Post by **rsrobbins** » 06 Jul 2011, 09:53

It was the #2 Coil Pack...runs great.
You guys are the best...
Thanks!!!!