Catalytic converter --> Kaput!
 

I was driving up from Sydney to Brisbane (for my wedding!) on Friday.
Over the course of the trip myt Rx8 slowly lost power to the point where I could no longer rev above 4k.

It got so bad that I stopped at a dealership half way. They found no probs and said it must be bad fuel. Up here in Brisbane now and it is worse then ever, plus I got a CEL, so off to the dealership.

This time they have found something - the catalytic converter is stuffed apparently. This would explain my bad fuel consumption I suppose but I did not know a bad cat had such an influence on the car, it is almost undriveable!

A new cat costs....2500 bucks! They are deciding whether it is a warranty issue or not. After 6000klms (6 mont old car) I would hope so! After the obligatory forum search I notice that there are a LOT of US owners who have had to have a cat replacement. Not many Aussies though.

So I have 2 quick q's

1) Has this happened to anyone before

2) If they refuse to fix under warranty even after my kicking and screaming there is no way I am putting on a 2500 stocker cat. Has anyone had any experience with hi flow cats in Australia on their RX8. Las time I got one they were about 500 bucks.

Oh yeah forgot to mention that this is one of my wedding cars so I have 3 days to resolve. Ahh the stress :)

I smell an issue that should be fixed under warranty. If you have any hassles, PM "Gibbo" - he has contact details for the technical director at Mazda, and apparently he is a "nice guy".

Which dealer did you take it to?

A bad cat should not affect fuel consumption or power. In fact no cat would give you an increase in power and 10 foot flames out the back/ Unless the computer shuts down because of this.

Brakes, now cats.....has this car got more tupperware than a tupperware party?

If you want to go down the after market cat job PM NRVOUS, he had one fitted for the east coast targa. It sounds great with the stock mufflers and has claimed real gains of 4kw at the wheels.

Either way I hope yours is covered by warranty.

If you want to go aftermarket, give Les a call and he should be able to make a custom job. You know the number ;)

If the cat and / or o2 sensor is stuffed, the it would definatley affect fuel consumption / power.

Cheers,
Hymee.

Hymee, god of exhausts, O2 sensor I understand, but why the cat?

I thought the best cat is a gutted cat and usually when cat's go they have ahole burnt in the middle of them that should be the same as a gutted cat

AMG, when the cat goes the insides can collapse and then block the outlet. Hence the increase in fuel consumption and drop in power....

Muzz, this should be a warranty claim...

Muzz, sounds like warranty. Be fair but firm with the dealer and maybe he'll let you have a loan 8 for the wedding. Good luck -- you certainly didn't need this

Not at all. Sometimes they collapse catastrophically. This chokes flow killing power and economy across the board.

I've killed more cats than you've had hot breakfasts :p

If they go "bad" and they overheat, then PCM knows about it, as there is a Cat. temp. sensor. So it will run richer to try to prevent any more damage.

Sounds like warranty, Muzz. Be calm, patient and affirmative. FFS - It has only done 6k!!

Cheers,
Hymee.

Seriously? :confused:
Hmmm..... I see a visit to an exhaust shop in the not too distant future. ;)

Back to the thread, sounds like it should be warranty because no way in the world should a cat fail after only 6000kms unless it was faulty.

$2500 for a Mazda cat? :eek:

You can buy yourself a whole new Hymee exhaust with high flow cat and still have plenty of change. ;)

Yeah - and I haven't even priced them up yet :)

Cheers,
Hymee.

If you used leaded fuel that would not be warranty I can't see any other reason it wouldn't be covered.

I had to have my stock cat replaced at about 4,000 miles, it caused a CEL and was definitely causing power robbing issues especially at higer rpm's

A cat that melted down or that's clogged WILL affect both FE and power!!! :mad:

I am sort of with AMG on the issue. YES! I am questioning the diagnosis since it is so odd a stock car with have cat problem and the Oz flash is so conservative.

Hymee how can someone know the catalyst is failing? I mean... how can they diagnose it without taking it out.

What is the reason of cat failing? Why is it to do with the richness or leanless of fuel?

Sorry of all this questions :p

I have done a number of cats in different cars over the years. Whilst I am no Rotory expert I can say that every cat that has failed on me has always without failure developed a rattle. The ceramics are the first thing to cracka and break when over heating, this causes a rattle within the metallic housing of the cat. When you drive it sounds like the exhaust is lose and hitting against the undercarrige of the car.

This is my experience and why I would seriously question what they have claimed about your car.

I guess the first thing is to trust your instruments - i.e. what the WDS tells you. I could have plugged my scan tool into Muzz's car on Caturday morning, but at that time it had not thrown a MIL, so it would not have picked up anything I think.

Cheers,
Hymee.

Yes I find it weird I did not get a CEL until 3 days after the symptoms.

I have a little theory going at the moment - when I stopped halfway to Brisbane at a mazda dealership (with no CEL) they did fuel pressure checks. They flooded the car several times whilst doing so. My theory is that this is when the cat was damage (or damaged further - enough to throw the CEL the next day).

That doesnt explain why the car was misbehaving up until that point however, so maybe the cat was already on its way out. I just find it weird for a cat to die for no reason - I've never flooded or stalled it over the 6000k's I have owned it and never put any additives in. So I will be making sure they correctly diagnose the issue. (Right now theyve just plugged it into WDS and got the CEL code, they haven't even pulled the cat off). I would love to see it - to get the symptoms I had the substrate must have totally collapsed and blocked off most of the exhaust.

I don't think there will be any warranty issues - they said they just need to get authorization from Melbourne as it is an expensive part. We'll see how it goes. Should have been done by now, but Cup day yesterday - Melbourne at a standstill :)

Maybe they are keeping it in the garage and checking out Hymee's trick exhaust eh?

I hope they gave you a loan car? They have seen my trick exhuast before. Keep us posted on the progress of this. I wonder if the Cat Temp sensor died if it would give that sort of a DTC? Of course, it is easy to make "a problem with the Cat" cover a range of related issues. If the Cat temp sensor was giving false readings, I can understand the computer going rich to protect things. Would love to know the full story.

Cheers,
Hymee.

Making ceramics is hard enough, but making porous shaped ceramics with platinum deposited on it is really tough. Any variations in density can translate to weaknesses when the ceramic is fired. Weaknesses can develop into cracks and then catastrophic failure under conditions of mechanical and heat stress. The things get really hot sitting behind a rotary motor, and I guess a statistical possibility of premature failure always exists. It's this statistical thing that is the reason for premature failure. It's impossible in mass production to get 100% of a product all lasting for exactly the same time. Say the average life of a CAT is 100,000km. If you get say 2% lasting 170,000km or more, then if the statistical distribution is "normal", you'll get 2% failing at 30,000km or less. As long as the driver hasn't been doing anything that the car manufacturer can point to as being a direct cause of this failure, then a case for replacement under warranty should be able to be made.

Good post, labrat.

Cheers,
Hymee.

Right the part arrvies this morning and I am supposed to have the car late this afternoon. Fixed under warranty.

Will let you know what the story was with the cat (and indeed if the car is fixed!) once I get it!

Thanks for comments everyone!

Well, first Pappy's disc's....now Muzz's cat. MA apparently aren't toeing the hard line with regard to all "consumables" on the RX-8. aus rx8 appears to have drawn the short straw with his clutch.....

Gomez.

OK I have the car back now.
When I picked it up the mechanic who worked on it and the faulty part were 'out to lunch'. So I did not get to see it nor talk to him.

However...as soon as I turned the key on my RX8 in the mazda carpark I knew that the fix had definitely worked. A glorious hymee-enhanced rumble spilled from my exhaust tips.

2 days ago ( while waiting to book in to mazda), ater I had 'the problems', I got a Hymee Exhaust fitted anyway as I was in Brisbane and had limited time. IT looked fantastic, but I was slightly puzzled about this brilliant sound everyone was talking about, cos mine sounded EXACTLY the same as stock after the exhuast was put on.

No longer, its a beast now! Plus of course I can rev as normal. The cat must have really restricted flow, enough for Hymee's exhaust to have no audible effect.

Now everthings fine, all working, sounds great, nice exhaust hymee. The delaership was very good, they did not try and point the finger of blame on me, they have written it off as 'bad fuel' (I am skeptical on that one) and replaced the cat at no cost to myself.

Now I am off to my wedding on Sat.