Burning smell when idling - CAT Failure?
 

I've been a lurker since the summer doing as much reading as I can on this forums, so I have definitely done searches for this problem that I am having but can't quite find anyone with the same symptoms

Car History:
Owned it since summer of 2009. Car is a 2005 MT w/80,000 Miles (130,000kms) unknown history about the plugs/wires/coils and no aftermarket engine mods.

Symptom:
1) After driving for a short period, come to a traffic light or a stop and a strong burning smell is evident - smells like hot plastic/rubber. Especially evident after I pull the car into the garage and turn it off - the burning smell lingers. Popping the hood, doesn't smell like the burn, exhaust doesn't smell like the burn, and doesn't smell like it is coming from the interior. Almost smells like brake or clutch but I am not a new standard driver and have never burned a clutch in my life and I don't ride the brakes!

Odd thing is that there is no single point where i can sense the smell from.

Only thing I can guess is that it may be the exhaust possibly overheating (IE Clogged CAT?) and causing it to overheat?

Other possible symptoms that may or may not be related:
1) This is the first RX8 I have owned, and I haven't driven any others to verify if the power is reduced from normal, but also, when at higher RPM's heading towards redline, the "journey" to the red line isn't completely smooth and consistent - the car seems to slightly hesitate a little bit at different points until and during redline - but nothing excessive

2) Seems to have a lot more white smoke out the exhaust but exhaust doesn't smell like oil/fuel/coolant - just what I consider normal.

3) Exhaust for a while smelled really bad like rotten eggs (CAT???!) but doesn't seem to be bad anymore

4) after turning the car off, the exhaust still comes out of the pipes for up to 20-30 seconds after it is shut off (Temperatures lately have been aroudn the freezing mark)

Disclaimer:
1) there is NO PLASTIC bag that is caught onto my exhaust! :p:

I was considering taking it to an exhaust shop and just putting it on the hoist to check the cat.


Anyone have any pointers or tips for an in love newbie to the Mazda world?:ylsuper:

Find a midpipe is the best test.

The midpipe just replaces the cat?

My first idea was that

1) you ran over a plastic bag and it melted on your cat. That happened to me and I smelled burning/melting plastic for about 2 years. Since you have ruled that out, on to the next one.

2) Engine gets rough around red-line? I've experienced this...right before my cat failed. This makes sense if you think about it because the car is producing so much exhaust and it can't get out of its own way. The cat is possibly creating a lot of back-pressure on the engine and causing it to stumble.

3) Also, you said exhaust continues to come out of the tail-pipes for 20-30 seconds? I'm no professional, but that seems pretty bad. You said temps around freezing? In NC we've been at near the same for about the last week, I've yet to see anything like it. My guess is that (continuing from 2 above) the cat is clogged and it is becoming pressurized pre-cat and then when you turn off the car, the hot exhaust is slowly working its way out of the pipes. Your cat may be your "bottle-neck".

You might be able to see a "glowing red" underneath your car after a spirited ride. Maybe try that first, obviously waiting until dark so that you can tell if it is glowing. If that doesn't yield anything, you can always check the cat yourself.

Hardest part is breaking free the bolts...but enough penetrating grease and elbow grease you should be fine. Inspection is a bit self explanatory...look inside. If it is failing, you should see the "honey comb" material starting to defect and not look right.

Good luck, let us know what you find out.

Forgot to ask...have you ever flooded the car? I understand that you are not the first owner so it is totally possible that it happened before you ever had possession of the car. Flooding events seem to always happen before a failed cat.

Wow - thanks for the reply - much appreciated.

Have never flooded it while I have owned it which is since July.

Your synopsis is similar to what I have been thinking as well.

I don't have the tools to jack the car up so I might bring it to a muffler shop to see if they can take a look at it.

On another note, would this be something still under warranty?

^^^

Yes, we have a warranty on the emissions components like the cat up to 80,000 miles I believe.

Could you update us on what was wrong? I have the exact same problem on my 04. It smells like burnt rubber in my garage if I drive the car for over 30 mins.

Also I have the same issue when I get over 6k rpm, the engine hesitates just a bit but nothing excessive. The RPM needle moves by chunk instead of smoothly

i haven't had a chance to bring it into the shop yet - but I called a local exhaust shop and he said some of the symptoms are of the cat but he suggested going out on a good drive, and feeling the exhaust pipe tip (carefully). He said if it is hot, then everything is likely okay. If it is cold but the cat underneath the car is glowing hot like another guy on this forum suggested, it may be the CAT. They will bring it into their shop for no charge to take a look.

I originally called the local Mazda Dealership first but I wasn't interested in paying $105 per hour for them to look at it.

Hopefully I can get it into the shop next week and I will definately update.

The only other thing I would like to change are the plugs - i have no idea what the previous owner did as far as changing them or when.

update plz

...this week I will get it in... I also ordered a set of coils so will be putting them in. Kinda clutching at all the straws of stuff that will also need doing. I know the coils are likely not the result of the burning smell, but want to see if I am missing out on some power...

Another issue that just came up.... P0037...Rear 02 sensor... This fail because the cat might be or other way around??? Must order new sensor and install....

The mystery continues...

Note sometimes the honey comb looks normal and it can still be failing. mine had bogging really bad took it off looked normal. problem still happened so I gutted it and problem went away. I still get the p0037 DTC code but I just scan the car for trouble codes when it's warming up to make sure there are no new codes.

FYI fox
 

I had the same issues, ended up getting a new cat covered by warranty. i also did plugs and wires at the same time.(70k km)

problem is back, burning smell again, slight loss of power, rough idle, cat glowing around o2 sensor as well. (71k km)

taking it back to have the coils changed, hopefully my new cat doesn't blocked again, although its free anyway...

i swear once i get this solved, im strait piping it, and my car won't see a cat or a f*cking air pump again until it's time for a e-test. lol

sry thread jack > anyone know if there are any back pressure issues with strait pipe? i know i have to prog out the CEL for the missing o2

I'm 99% sure now that your cat has failed. As I understand it, this sensor makes sure the Cat removed all the unburned hydrocarbons (checks for clean air). If the cat is not working, this sensor picks up elevated levels of hydrocarbons and sends a signal. Get the cat replaced, or get a Hi-flow cat from any number of places. Using a straight-pipe (race-pipe) will still likely result in a CEL, as the unburned hydrocarbons will not be removed.

As for the coils, check out the BHR coil upgrade kit. After replacing the coils twice, you could have nearly paid off this kit. It is an awesome deal, and a huge relief knowing that the coils won't fail randomly.

RP Supercat - best of both worlds (pass emissions with higher flow).

^ +1

sorry for thread jack too.

It is normal that after spiriting/good driving the place around o2 sensor on the cat is glowing? I didn't feel any power loss etc.

Now that I think about it -My 04 6 speed had some smelly moments after driving it hard (not tires of clutch.. but I thought brake pads). I haven't noticed that smell since they replaced my catalytic converter last year.

Mine had a nails sliding on metal sound when braking or accelerating hard- which ended up being parts of the failed cat in the exhaust. That's how they figured out the cat was bad (duh).

That was at 31k miles.

Good luck with it.

I don't think so (i'm still learning myself lol but have had the car for 6 months now)
That is a "cat glowing red" << search that and many threads will come up. You only see it around the 02 sensor because that is almost the only part of your cat that you can see. The rest of it is covered by a heat shield. >> get it checked emissions warranty is good till 128k km

Any update on the smell?