Car: R52 05 MCS JCW

When I floor the car -- RPM is around 6000+, I smell a very strong -- sort of rotten egg or food smell inside the cabin. I don't know where it's coming from.

So I did a bit of searching around on this forum, and many people said it was the cabin air filter, exhaust leak, bad catalyst converter, fuel with too much sulfur, and bad clutch.

While my clutch is going, it's not bad enough to slip. I did the stalling test in 3rd gear, and the car stalled. Clutch is worn, but bites good.

I don't know about fuel with too much Sulfur, I only shop at Mobil/Arco/Shell, whichever are closer to me.

I even smelled the exhaust of the car -- while the smell was very similar to what I was smelling inside the cabin, it wasn't identical.

Cabin air filter hasn't been changed in a while, but I never use the AC or air recirculation anyway. I always roll the windows down.

Today, I tried to reproduce the problem, and apparently it only shows up in 3rd gear at WOT and gets much stronger in 4th gear (again, WOT). Problem is, 3rd gear tops out at 88 MPH and 4th tops out at 105 MPH, so I am leery of testing this out on the freeway. 1st gear and 2nd gear WOT have absolutely no symptoms of smell.

In your opinion, do you think it's the catalyst converter? I know Mini has a 8 year/80,000 miles warranty on the catalyst converter, and my car is on the 8th year and 630 miles shy of 80,000 (actual mileage 79,370). If it is the catalyst converter, I should probably take it in before the mileage rolls over 80k.

What do you think?

Any help appreciated.

 

I do know what smell your talking about.. I call it the rotten egg smell.. It can be a converter or just the type of gas your using... But in your case since your so close on your converter warranty type deal I would bring it in.. They can test it for you.. Once that is done you can decide what to do next.. It just could be a bad converter... good luck!!

 

Clean out the old fast food bags from the back seat....
OK....if that is OK....
Then the cat...sounds like a badtank of older gas....
The sulfer smell should go away with the next tank....
Traditionally many think the cat is bad about when you get the smell....but it seems to be OK with fresh gas...guess it is just burning off some deposits.

 

P.S.
Still look at the cabin filter....
Mice have been known to make nests in them....

 

A few WOT pulls will get that smell, it will be stronger with a cat that isn't working efficiently anymore.

 

Rotten egg smell is classic catalytic converter

 

Try switching fuel brands..

 

Update:

Try as I might, I can't consistently produce the rotten egg smell on demand. Some days it's perfect. Other days, you get the smell as soon as the rpm gauge passes 6000 under load.

My problem is, that if it is indeed the catalyst converter... if I can't consistently reproduce the problem, then the dealer must likely won't be able to.

Because before the dealer takes a look at the car, I have to agree to a $150 diagnosis fee first. If there is a problem with the catalyst converter, then I don't have to pay anything. But if there is no problems (dealer can't reproduce the problem), then I'm out of $150 and the continuous smell.

My car is low on gas right now, so which gas station do I use?

 

Update:

I really thought it was the catalyst converter, so I took my car to a smog station and had them do a pre-test on it. It was only $20, so I figured, why not?

My idea was to compare the old smog test I had back in 2011 to the current one and if the smog results were worse than before, then I could have evidence of a catalyst failure...

Well, turns out that my car is actually running cleaner than before! I don't know if that's due to the spark plugs that I changed a while ago, or the Royal Purple oil, or the type of the gas I use... but now I'm back to square one.

Any ideas? The rotten egg smell still occasionally comes up under hard acceleration. I have a wild idea that it may be the exhaust manifold screws not being tight, so under WOT, the air pressure forces the manifold just a crack, enough for me to smell it?

I don't know, I'm just throwing ideas at the wall.

 

My car does this. In fact, most cars I've owned did this. Another way to reproduce is accelerate up a grade on a freeway. I don't know, just seems like a normal car thing.

 

My '09 Clubman S with 40K-55K miles did this under heavy acceleration until I got my engine replaced. Since the new engine, no smell.

I'm not saying that your engine needs to be replaced, but something changed when they put the new engine in that the smell is no longer there. I still have my original cat.

I always assumed it happened when the car was under heavy boost, but I never did really know the reason.

However, the smell was exactly as you described, and happened under WOT, but only some of the time. My passengers would always ask who was farting. I told them it was my car, and no one believed me. LOL.

 

Agree with changing gas stations for at least a few tanks.

 

I agree with the gas theory. I just picked up a pre-owned 2006 R53. Dealer filled it up before I drove off. I noticed the smell bad the first couple days, under hard accel I was about to bring it back to the dealer. Filled up with a new tank, huge difference. Still have a bit of lingering smell sometimes in 3rd to 4th gear change under load. Guessing the next full tank will clean that out as well.

 

It's far from normal. I've owned 32 cars over the year and I had it happen once and that was on my Suzuki Samurai and it was the CAT.

 

I should mention too that this 2006 only has 21,800 mi on it, so if it is a bad Cat I would be really surprised. It was owned by an old couple, garage kept, and just driven in the spring/summer.

 

catalysator destroyed by sulfur

 

reviving a thread from June/July of 13 . . .

 

Yeah, well I just bought my first Mini so... what's your point a$$hat?