Raw Eggs/Burning Smell from exhaust

[SallySpeed3]

I know that when you eliminate one or both cats on the speed3, or any car for that matter that the exhaust smell is going to be more noticeable. I personally have only replaced the 2nd cat (testpipe). But the smell I get sometimes, while the car is moving mind you is like a burning raw egg smell. Just wondering if this is normal, or something I should be concerned with. I cleaned the exhaust tip which was basically black and that seemed to help a little, but I can still smell it. I also recently put an ATR Stage 2 map on my car and I'm not sure how great the car is running, so maybe that has something to do with it.

 

[ucMP3]

If you still have 1 cat in the system, it's fried. Time for a new one; or time for a straight pipe.

Rotten eggs/sulfur is the smell of a cat thats ate up! You may want to look into why your cat is worn out, tho. Too much unburnt fuel getting to the cat? Are you running toulene or race/track fuel ever or anything?

 

[SallySpeed3]

Crap, I think you're right. I just threw a CEL on the way home and I have no doubt it's from the O2 sensor on my downpipe. No I don't run race fuel, just 93 octane. I'll run to Autozone after work and have them check it. I'd use my AP but its currently with COBB. Just last week I flashed the Stage 2 map to give it a try, Could a bad tune lead to the cat getting fried?

Besides having the continual CEL code is there anything bad that could happen to my car? I'm assuming to get a new cat put in would be expensive.

 

[ucMP3]

Crap, I think you're right. I just threw a CEL on the way home and I have no doubt it's from the O2 sensor on my downpipe. No I don't run race fuel, just 93 octane. I would check the code myself with AP, but its currently being worked on by COBB, hopefully they'll get it back to me by tommorow and I can switch maps.

Besides having the continual CEL code is there anything bad that could happen to my car? I'm assuming to get a new cat put in would be expensive.

An OEM replacement cat will be very $$$, probly over $500 I would guess... I'm not sure, I don't know a ton about the Mazda 3 & 6. But, you can get aftermarket equivalents for under $200. Or you could just gut the cat you have or replace it with a straight pipe...

I wouldn't let it linger, tho. The cat could become completely clogged, and could end up stopping all exhaust gases, making it reallllyyy hot. I've heard of people blowing headgaskets and such from this.

Actually, I was at my bro's house last weekend, and he was replacing the exhaust on his quad, because his cat clogged and it had actually blown a hole thru the exhaust about 6" x 6" right before the cat due to the pressure! lol

 

[Jchouin1]

Crap, I think you're right. I just threw a CEL on the way home and I have no doubt it's from the O2 sensor on my downpipe. No I don't run race fuel, just 93 octane. I'll run to Autozone after work and have them check it. I'd use my AP but its currently with COBB. Just last week I flashed the Stage 2 map to give it a try, Could a bad tune lead to the cat getting fried?

Besides having the continual CEL code is there anything bad that could happen to my car? I'm assuming to get a new cat put in would be expensive.

You shouldn't run the stage 2 map without a downpipe as heat becomes a big issue with the increased boost. On another note, if you need a cat, mine has about 30k miles on it and I'm willing to part ways with it. PM me if interested. Oh, and the stock second cat (front pipe) is $644.41 from Mazda, and primary cat on dp is $938.26, not that anyone should consider paying such an amount for this part!

 

[SallySpeed3]

Yea I'll definitely have to get it taken care of. I'll stop by meineke also on the way home and see what they have to say. I didn't really want to have to make my exhaust a complete turbo-back. Maybe they can replace the one in the stock dp with a high-flow cat. What bothers me is not knowing what exactly caused it. Hopefully its the Stage 2 tune which I'll definitely get rid of once I get my AP back.

Jchouin....Just saw your post, I'll definitely let you know soon if I want it. If meineke tells me they can replace the cat thats in the stock DP then I'm gonna go that route, but if it turns out I need a whole new dp I'll definitely get it through you. thanks.

 

[Jchouin1]

Yea I'll definitely have to get it taken care of. I'll stop by meineke also on the way home and see what they have to say. I didn't really want to have to make my exhaust a complete turbo-back. Maybe they can replace the one in the stock dp with a high-flow cat. What bothers me is not knowing what exactly caused it. Hopefully its the Stage 2 tune which I'll definitely get rid of once I get my AP back.

Jchouin....Just saw your post, I'll definitely let you know soon if I want it. If meineke tells me they can replace the cat thats in the stock DP then I'm gonna go that route, but if it turns out I need a whole new dp I'll definitely get it through you. thanks.

haha don't you love waiting for your AP? I sure don't!

 

[SallySpeed3]

Ok so little bit of an update. Took it to autozone. Code came up as P2188 - System too rich at idle. Probable causes according to their computer
1. rich air/fuel ratio. Might be accurate because of stage 2 tune.
2. EVAP purge system malfunction (no idea what that means)
3. Engine mechanical malfunction (could be anything)
4. HO2S (heated oxygen sensor) malfunction. Most likely this one.

Then drove to meineke and after talking to the guy he suggested taking it to the dealer because he said all catalytic converters and sensors have at least a 60k mile warranty. Only problem is I've messed with the ECU/intake/and exhaust. I can easily put the stock testpipe back in and also the stock bpv. I stupidly got rid of the stock intake so no luck there. I reset the ECU when I got home just to see what would happen. I figured if the O2 sensor really is blown the ECU would pick it up right away and I'd get a check engine light, but it didn't. I even smelled the exhaust and it didn't smell like raw eggs. I'm going to baby the car until I get my AP back, no boost at all. Is it possible that maybe my cat isn't fried? Maybe like someone said before, the heat that Stage 2 causes could be making the cat not perform well under high boost? Anyway, not sure what to do at this point, next step tho is flashing my old Stage 1 map.

 

[Darth Vader]

The egg smell is normal from cats. it can come and go. A failed 02 is causing the system to run super rich and is making the cat work harder. That's the egg smell producer.

Evap purge is the system that collects gas fumes and returns them to the tank, closed loop.

 

[SallySpeed3]

Hmm interesting. Do you think the O2 sensor is ruined? Wouldn't the ECU be able to tell that when I started it up? I guess I'll know if the check engine light comes on again. If the car is running super rich will it cause the car to hiccup during hard acceleration? I forgot to mention that earlier. It was doing that from time to time leading up to the check engine light coming on.

 

[ucMP3]

Ok so little bit of an update. Took it to autozone. Code came up as P2188 - System too rich at idle. Probable causes according to their computer
1. rich air/fuel ratio. Might be accurate because of stage 2 tune.
2. EVAP purge system malfunction (no idea what that means)
3. Engine mechanical malfunction (could be anything)
4. HO2S (heated oxygen sensor) malfunction. Most likely this one.

Then drove to meineke and after talking to the guy he suggested taking it to the dealer because he said all catalytic converters and sensors have at least a 60k mile warranty. Only problem is I've messed with the ECU/intake/and exhaust. I can easily put the stock testpipe back in and also the stock bpv. I stupidly got rid of the stock intake so no luck there. I reset the ECU when I got home just to see what would happen. I figured if the O2 sensor really is blown the ECU would pick it up right away and I'd get a check engine light, but it didn't. I even smelled the exhaust and it didn't smell like raw eggs. I'm going to baby the car until I get my AP back, no boost at all. Is it possible that maybe my cat isn't fried? Maybe like someone said before, the heat that Stage 2 causes could be making the cat not perform well under high boost? Anyway, not sure what to do at this point, next step tho is flashing my old Stage 1 map.

The ECU takes ~50 miles to reset itself. So at that point it may throw the cel again. Or, it may not do it again until you're getting on it and cause the heat build up again.

On another note, I have never heard that it's normal for a cat to give off a rotten egg/sulfur smell... Even intermittently.

 

[Darth Vader]

It's possible. Yeah, running really rich could cause power loss and hicupping and the stinky cat smell. The CEL being on has as a primary cause failed O2, as that's one corner of the lambda (emissions/feedback) system on all cars.

The stinky cat smell WILL happen, if the cat is exposed to high unburnt fuel in the exhaust . It's not "normal" in the sense that all is well, it is just going to happen in those circumstances. It can rarely happen when a new cat is installed but, it goes away after a while in those circumstances.

 

[ucMP3]

It's possible. Yeah, running really rich could cause power loss and hicupping and the stinky cat smell. The CEL being on has as a primary cause failed O2, as that's one corner of the lambda (emissions/feedback) system on all cars.

The stinky cat smell WILL happen, if the cat is exposed to high unburnt fuel in the exhaust . It's not "normal" in the sense that all is well, it is just going to happen in those circumstances. It can rarely happen when a new cat is installed but, it goes away after a while in those circumstances.

That circumstance will eventually destroy a cat, tho... So if that smell doesn't mean your cat's dead, then it at least means your cat is sick/dying.

 

[SallySpeed3]

Well either way it looks like I'm gonna need to replace the sensor or the cat. Would I be wasting my time at the dealership cause of the mods?

 

[ucMP3]

Well either way it looks like I'm gonna need to replace the sensor or the cat. Would I be wasting my time at the dealership cause of the mods?

Not necessarily, the intake is the main visible mod, correct? I would put the other things back to stock if you can and from my experience, an intake shouldn't be an issue... But I would check with someone local to you who has maybe used the dealership your going to, just to make sure.

 

[SallySpeed3]

yeah unfortunately the dealer i bought it from is an hour and a half away, the only other dealer is still like 25 minutes away.

 

[SallySpeed3]

Update

Well somewhat of an update of my problem for any that care. I called the mazda dealer closest to me (about half an hour away) and told them of my situation. They informed me that they weren't "Speed" certified and that I should take my concern up with the dealer that I purchased it from (over an hour and a half away). So I decided just to take it to meineke and worse comes to worse I'm out $250 for a new O2 sensor if thats the problem. Well the guy in charge wouldn't even touch my car because of my mods. I debated him a little bit but he wouldn't budge. I asked him just to test the
O2 sensor to see if it was functioning properly and he wouldn't do it. I then had to leave town for the weekend. Taking it to Midas tommorow who assured me they would find the problem, even with my mods, and fix it. In trying to further diagnosis if it is indeed my O2 sensor, while looking at my mpg on the dash (info button) I notice that when I come to a stop it's still reading like I'm driving, almost as if its on a 3-5 second lag. Anyway, I'll let you guys know what happens.

 

[SallySpeed3]

On an impulse last night I took out my MAF sensor, there was black soot all over the bulb (the thing that detects the air temperature). I cleaned that off, brushed off some other crap around the housing, blew some air into where the actual sensor wires are, they didn't look dirty to me, and put it back in my car. Driving my car to midas this morning, it seems to be running fine. No hesitations or anything, I even went WOT and nothing happened. Just picked my car up from Midas and they said it appeared that it was running fine, no codes or anything. Could a dirty MAF sensor been causing my problems?

 

[coyfish]

Why didn't you just take your mods off? Take out the full intake, midpipe, and the bpv. Shouldn't take over an hour. Gauges, motormount, shortshifter, plugs, and boost tubes can stay.

Anyway gl getting your problem solved.

 

[Sport6]

Yeah a dirty MAF could definitely cause the problems you have been seeing. Dirty MAF would not read as well as a clean one..leading to the overly rich conditions (might have been for some time) and cause the cat to get really hot (which causes the smell).

I would drive it around another week or two to see if you problem comes back.