enginelight and burned catelytic
 

Hello Guys!

I need some help again.....my english is not so good, but Ill try to explain...

Mazda garage in Norway doesnt have any good solutions but.....

I had problems with my mazda Rx-8 HighPower 231Hp after i had a new engine installed....

The enginelight turns on after driving a while...

The failure code:

P0172 System too rich ON 2 Fuel system

RPM sometimes, not always jumps while the car stands still. While driving the car it sometimes chokes when it doesnt have enough rpm and I have to restart the car...

The Mazda garage told me that the catelytic is burned and I need to replace a new to solve the problem with the engine light and the jumping rpm. The catelytic will cost me more than 2500$ to replace :banghead:

Is it possible to do something with the rear o2 sensor, so that the engine light will disappear??? Or do I have to purchase a new catalytic??? Will it solve the engine jumping rpm and the choking??

The reason im wondering is because I also have an Replacement Pipe with 2 holes for both O2 sensor that i can change for the stock catalytic converter section..but the enginelight will still appear :-(

What to do?????

I will be greatful for all ideas or solutions...:)

A lot of this answer depends on the fact that you live in Norway. What are the laws there? I only really know about the US, where you are required to have a catalytic converter that is working properly. Depending on the laws, you may have problems with either Mazda or the government if you don't have a working cat.

With that said, and ignoring the rules, you can definitely put on the replacement pipe and the car will work fine. The car will be much much louder, however, and will probably smell a little more. You will also probably (not definitely) get the CEL code again. Most people who remove the cat

Another option is to buy an aftermarket high-flow cat. There are a number of companies that sell them in the US for about $400 USD. I'm sure shipping to Norway would be at least $200, but that is still much much cheaper than buying a new one from Mazda. These high-flow cats will be louder than stock but quieter than just an open pipe. It would also almost-definitely prevent a CEL from coming on.

Good luck....

I will also add- I am not positive that this CEL means you definitely have a bad catalytic converter. It's very possible that it is some other problem. Anyone else able to comment?

my mechanic told me when he looked inside it, that it was burned out.....

But anyone else here that could give som advise?

Thanks a lot Elysium:)

if its all burned out, the only way to *fix* it is to replace it

but even with a *burned out* cat, it shouldnt cause the CEL u mentioned (system too rich)

it's probably the front O2 sensor thats causing the issue. cuz the system needs oxygen feedback to get the correct AFR

I gonna buy an universal catalytic coverter to replace the original. Will that throw an CEL??

Because its much cheaper...

Anyone with a comment??

You have to cut the open pipe to make it fit, in theory it will work, but you better be sure ur cat is the *special* kind, since rotary exhaust gas is a lot hotter than piston's. Your *new* cat might just die in a month or so.

Could it just be "burned out" based on the service tech never seeing a used cat for an 8? We do spit a lot of carbon in there and it would look thousands of times worse than what they would be used to seeing. Also...with a new engine and an old O2 sensor might the engine actually be running too rich based on the feedback from the dirty O2 sensor? That would cause the idle to be all over the place making it run super rich and super lean. I dunno...Im an electronics junkie by trade so I would wait to talk to MM or Charles Hill.

Is this replacement pipe a race/cat-delete pipe?
If so, I would install that and see if you get the same CEL code.
When I had a mid-pipe, I believe I got a P0037.
Yes, you'll still get a CEL, but if the code is different than what you had (P0172), then there is a better chance that the cat was the issue.
but if you go this route, I would drive it for a few days and then read the code.
I've managed to go a few days before the CEL would even appear!

The only thing that Mazda mechanics told me was that the cat was burned during the engine brokedown. And that extra heat was the cause to the burned cat....

He had been looking into the cat and that it was melted in the half of it...and that also caused the choking and jumping rpm....Is that true??

But the car has been droven with the racemidpipe with no cat from the previous owner. Whren i bought it restalled the original cat and drove maybe 3000km-4000km, then the engine brokedown...

So could it be so simple as changing the o2 sensor. Which one to change? That one in front or that one in back??



Thnx for all help folks!!

Depending on how far it melted I would disconnect the front one and see if your error changes like Jon said. If it did I would replace the front. You may not even have to replace it if the glass actually melted around it...might just have to poke a scredriver through.

reversing the question a bit......if my cat is burnt/melted/damaged, will the car thrwo a CEL to let me know?

Hello Nycgps!

It seems that you are one of those who has a clue during my CEL....

I have some questions for you...

Back to the jumping Rpm it seems to run from 0,7rpm-1,5rpm...It only appears sometimes...Sometime it chokes and i have to restart...does it have anything to do with the cat??

Will it be gone if i change the cat?? Or is it the gear manuel switch like you told me before? Or the coil?

Thanx for kindly help!!:)

if it stops when you push in the clutch it is the neutral position switch.

beers :beer:

It doesnt stop everytime...? But sometimes...If the neutral posistion switch is broken..Wouldnt it throw a CEL?

yes,

but if the problem is intermittent like mine was it takes a long time to get the code.

beers :beer:

Hello again!

I got a new universal replacement cat intalled and still have the same CEL....

But the funny part of all, is that i hoped this jumping rpm, would also disappear! But it didnt:-( However to that, i took of the batteri to reset the CEL and Whooops the car runs smooooth without any jumping rpm....

After driving a while the CEL came on again....And little bit after... the jumping Rpm appeares again :-( Off with the battery and jumping rpm is gone again......

Back to the mazdagarage again :-(

Any one who got any clue??

vaccum leak or bad neutral switch.

I call for broken Neutral switch.

and Most Universal Cat will not Survive the exhaust temp from Rotary engine for too long ...