Let me give you a brief history of my RX-8 before we get started on this story. I purchased a recovered theft 04 Sunlight Silver in February of this year, and finally got the paperwork for the tags/title straight two weeks ago so I could start driving it. During this time it sat in my dad's driveway, and I would start it about once a week, and run it for an hour or two to keep the battery charged. The battery would still die on me, and I had to jump it three times.

Anyways, when I first took it on the road, I noticed at times a smell like rotten eggs or fart, you know, the sulpher smell. I have been reading this forum for some time now, so thought nothing of it since several people had commented on that smell being normal, perhaps from breakin on clutch or a little smell from the cat. Well as the days went by the smell got worse.

Finally, last wednesday, I took it for a nice long ride to a friend in Jersey City, we were gonna go try some White Castle burgers after seeing the movie. As we got off the garden state parkway, the whole car filled with the terrible odor as soon as I slowed down below 25mph. As I started to park in front of her house, I noticed the electrical system in my car seemed to go haywire. Every time I tried to turn the wheel, the lights would dim, the radio would reset, and the idle dropped to almost a stall. Finally, it did stall, while I was parked halfway in the driveway, halfway in the street. I tried to restart, but it soon became obvious that the battery was completely dead. We jumped the car, and it started right up, but was running at a high idle with the CEL on, and acted as if the throttle was stuck halfway open - it would stay at 3,000 rpms whether I punched the gas or let it sit. the engine was noticably affected everytime I turned the wheel or turned on or off the headlights. I was able to move the car about 4 blocks before it stalled right after going through a light. So I popped the hood. I was greeted by a horribly intense smell of sulpher and saw that there was fluid bubbling out of the top of the battery. I grabbed some paper and wrapped it around the top (I didn't want to burn my hands), the battery was warm to the touch but not burning hot, so definitely in operating temperature.

Anyways, fortunately my friend's dad had a spare car battery in his basement - he let me borrow it. I replaced the old battery with the used one from his basement and the car started right up, just fine. We went to white castle, got our burgers, laughed about our own harold and kumar style adventure (minus the wacky tobacky induced cheetah ride) and I drove home with no issues. When I mentioned my story to my dad, who's been a mechanic for 20 some years, he said it sounded like the battery was "sulphating" - apparently, when the car wouldn't start to put it on the truck before shipping it accross country after I bought it, the salvage yard dealer swapped out the battery in it for a used one from a volkswagen he had sitting on his lot. That battery had definitely seen better days.

I went to pep boys and bought a new optima red top, but discovered that the posts were in the reverse position on the top so had to swap it for a bosch with the same rating as the interstate one recommended here - so far its starting nice and quick, no issues, and a smoother idle for some reason. I guess that may be from the PCM reseting, or perhaps because there's a more stable voltage flow from the newer battery. At least that's my guess.

So if you ever smell sulpher in your RX-8, there's a possibility it may be from more than just the cat or clutch. Oh yeah - the smell is gone except for a slight residual whiff which may (hopefully) disappear in time with my nice berry scented odor magnet. Next project? repair the minor paint chips and scratches on the bumper from the previous owner(s)/thief. I love this car!!!

I've had this problem happen to me in a '89 Grand Prix, and my '95 Talon. The problem both times was an alternator that was in the process of going out.....not really the alternator, but the voltage regulator in it. The alternator would overcharge the battery and "cook" it. You might want to get yours checked out, as the problem was intermittent at first for both my cars. Whatever you do, don't get an Autozone "Duralast" alternator. They're warrantied for life, but you'll replace it every 1-2 years for the same problem.

The battery makes more sense as the source of the slight sulfur smell that many owners experience, than clutch or catalytic converter. The way that incoming air is ducted around the battery for cooling may be conveying any slight outgassing to the interior. This occured to me when I topped off the water in the cells not long before I replaced the OEM battery. The sulfuric acid smell was a closer match than a slipped clutch smell.

Very interesting post. I did not have (yet) this issue but I'm on the watch... I keep the display of my radar detector to voltage monitoring and so far, nice and stable at 14.3V while driving.
I wonder if you got corrosion on some engine parts from having this issue for long time. Another possibility for battery failure is the improper size - there is a TSB explaining how much space one needs around the battery, for cooling. Maybe the VW one was too large and could not cool enough. Plus, running the car without moving it would make things worse (it cools by air movement, there is no fan to help it).

In both of my cases the alternator was registering 14 volts or so, but it was charging at too many amps, therefore the voltage did not let me know anything was wrong. Many parts stores are able to check your charging system, volts and amps.

Thanks for the tip - I'll definitely get the alternator checked out. There is a little residual odor but not strong at all and it gets less every day. I checked all through the engine bay in areas that might have been affected by the acid, and it looks like the only things that may have been affected were the black plastic parts around the battery box - the plastic seems to be unaffected so I'm not too concerned about that. The acid did burn a couple of holes through the newspaper I wrapped around the battery on my way to Pep Boys to get a new one - fortunately it didn't get on the carpetting in the trunk else I would have been p/o'd

I'll have to admit, I was one of the ones that said catalytic converter whenever people said sulfer smell. I have had a battery meltdown due to a overcharging voltage regulator/alternator on another car. I guess I am pregudest at the moment. I have had to replace 2 cats on my car to date (10K mi.).

You may want to check you radiator...the air vent for the battery box will allow acid to drip on the rad if enough escapes....acid and aluminum rads are a bad combination

hmm interesting story...glad i dont' have a sulpher smeel in the cabin :D..but i do ahve a interesteing slight smell out the exhaust i've noticed..hehe looks like it'll be new cat time for me soon.

Do you have an update on what was wrong w/ your car?

Do you have an update on what was wrong w/ your car?

That was 3 years ago. ANyway I just took mine into the dealer. 04 with 35K miles. Smelled like sulphur. Shift boot was craked and the trans fluid was leaking on the exhaust. He said that they have recently seen a few like this. SOmething to keep your nose peeled for...