I have READ just about every forum on this website, still can figure out why my cat is glowing red. I have change and upgraded the whole ignition system, clean MAF sensor and other sensors but for sum reasom my cat is still glowing red. Let me not forget to mention that this is my 3rd cat in less than 2 months. Im starting to think the problem is way bigger than the ignition system. It doesnt feel like the car is being bogged down, but with cold starts ill get a rough idle and a stall but the more that I drive it and it warms up, it just idles a little weird but doesnt stall. The car seems like it drives fine but then i look under ther car and im getting this mean red cat looking back at me.

The dealer did say the compression test was under specs but failed to tell me the numbers even after asking. Do you guys know what could be wrong with the car?

Again literally just change the ignition system about 3 weeks ago. That was before i knew the cat was clogged. Got the cat changed swapped out the spark plugs again after changing all the wires, plugs, and coils. Cat still was glowing, so i used my warranty the next day so brand new cat and that Bi7ch still glowing red like a damn demon or something.

 

You didn't read or you'd have your answer.

Is you replacement cat OEM or aftermarket? Low comp is low comp. Any reason you can't just go catless?

 

I live in BAMA, so that may answer your queston. We dont really have emissions test here but there is no shops here that will remove the cat (obvious reason) and i do not have the tools to remove the cat.

Would you consider that to be the best idea ?

 

Is this from hard driving or cruising around? Mine was healthy but will have a dim glow after I hold it at 5k RPM or so for a little while.

Personally I would look at your fuel trims to see what's going on. If the ignition isn't the issue(make sure everything is connected correctly), then you have excessive fuel entering the exhaust to overwork the cat.

 

Okay this is where im confused, because i have read on here and seen that people whose cat was clogged and drove it hard was a brighter glow than the ones that drove it soft cause a dim glow. No matter how I drive it is a dim glow, dim enough to if i park in a parking lot with lights i can barely see it. I literally have to be in dark spot to see it but it still worries me. I am sure everything is connected correctly there was a diagram on here that i used when i replaced the ignition system. I checked, checked, and discount double checked to make sure things were connected correctly. But just like your its just a dim glow.

 

What type of catalytic are you running? Mazda OEM or aftermarket?


what ignition are you using? factory oem coils and wires? aftermarket?

is an independent shop the one that's swapped out 3 cats for you recently?



the reason we're trying to figure out which parts you're using on your car is because while there are a lot of parts available for the RX-8, not all of them are going to hold up, especially aftermarket cats.
They cannot handle the little firebreather that is the Renesis engine and many will fail quickly.

 

@Jedi54 Yes it was an aftermarket cat. Would it be better to just delete the cat in all, like i said no emission controls here. We dont test our emisson regualar anyway or even at all. For the wires and coils they are aftermaket upgrades. Yes same shop did the cat.

 

Also yall are awesome with these quick replies I appreciate that!

 

we're here to help.

I've seen some aftermarket cats get cooked in a matter of days.
when you look at the exhaust gas temperatures of a renesis and compare it to even say a Subary WRX, it's not even close. Some of those cats simply cannot handle those temperature levels.
I would try to source a used OEM cat (not cheap)
another option is the RP supercat RX7.COM | RX8 Exhaust products I had one and it lasted me years.
There are a few metal cats @TeamRX8 has some experience with some of them I believe
or like you said, you could just go with a midpipe (there's plenty of options for that) but a catless rotary is loud and smells.


which ignition kit did you install?

 

Yeah if you are just casually cruising around and it still glows, then there is a problem.

Removing the cat will result in a pretty terrible smell and your CEL will also come on with the P0420 code, but otherwise won't have mechanical issues. On the other hand, a cat that can withstand the rotary exhaust is pretty expensive, usually as expensive as the OEM one.

 

@Jedi54 The ignition upgrade was from bennetbuiltperformace.com the LS ignition swap kit.

@UnknownJinX I guess i will be looking for a better cat tho midpipe sounds like it could be a better option. I am not much worried about money when I bought the car i understood how much money was about to eat through my pockets, starting with the premium fuel. i am just trying to make it last until it time for the engine to be rebuilt.

Im guessing driving it isnt the best idea until i figure out something with this cat, right ?

by the way it is a 2007 with a lot of miles. I will post a pic on here soon. it climbs up in the RPM pretty smooth and still is able to redline, usually after i redline it one time it idles 20x better. but i should have to redline it everyday to have a smooth idle, and dont worry I drive it soft for at least 20 minutes before i even think about redlining it.

 

How old are your spark plugs?
If they haven't been changed with the coil kit one or more of them could be corroded or fouled.
Check the ceramics' not cracked.
Be sure the wires are snapped on tight and not bunched together where they could arc.
Get a OBD scan.

 

What condition was the original cat in when it was removed? Had the element disintegrated? Because parts of it could be blocking your exhaust downstream from the cat, causing build up of heat and pressure enough to cook your new cat.

 

@BigCajun everything was change with the new cat and i just check my plugs # days ago and they were fine @Loki that was the conclusion i came to becuae it not the O2 sensor ring thats glowing its literally the pipe that attaches to the cat going to the backside of the car.

 

@Loki an OBD scanner was one of the first things i got and it was throwing back a code that correlated with a clogged cat so i was told i immediatly took it to the shop when i found that out.

 

OEM cat has two substrate blocks. If the rear block has collapsed, that can cause over heating...hence glow. Best is to jack it up, remove O2 sensor, run a boroscope to inspect.
I collect used OEM cats from the junk yard for fun. At one point I think I had like 3 OEM cats. :D

 

That seems to fit then, the exhaust pipe is thin and will get to glowing temperature much faster than the thick-walled cat. Get it all taken apart and examined. First time I hear of the cat back glowing red, that's a serious fire hazard seeing as there's a fuel tank above it.

 

Surprisingly some of the highest EGT temps will be cruising. The AFR is leaner and there is more than enough airflow for things to get super hot.

Personally I would look for a used OEM CAT if you don't like the smell.... or go CATless.

If you have a lot of extra fuel being dumped into the CAT from a leaking injector or from poor ignition it will heat it up a lot too... that's what it is supposed to do.... basically burns the extra fuel in the CAT

Figure out if you have a problem with fuel and ignition.... if you do fix it.
Low compression results in bad burn in the combustion chamber... so you can have a problem from that as well.

Start with the basics... and then start looking at other stuff after you have ruled out the cheaper easier stuff