CaymanRotary

Hello everyone,

I am here in the Cayman Islands with 2 beloved family RX-8's and I have been a loyal reader of these forums.

This site has helped me greatly and was wondering about a popular YouTube mechanic Scotty Kilmer who suggests to use 1 gallon of lacquer thinner in half a tank of gas to help clear up catalytic converters.

Has anyone ever tried this on an RX8 and could it be harmful to the rotary engine? Having an issue with my cat that it is still detecting errors from brand new O2 sensors. I don't know if the new sensors are working or that the cat is clogged. The car is a 2004 automatic with 80k kilometers. Car is in fine working order and everything works superb except for this one thing.

I'm tempted to try this method but am unsure if it will damage anything by attempting it. It is petroleum based so it should burn through fine with premium gas. Should I go for it?

Loki

iTrader: (1)

You're welcome to try to discover for yourself. I'm more than a little skeptical. Here's the thing: RX8 cats often fail structurally. Thinner isn't going to put it back together. If you do try it, report back.

So I would take the cat down, examine it and go from there. P0420 is pretty conclusively the cat, and not the sensor, and you've already replaced the sensor, so it might be time to face the music. Cats die due to failing ignition, and it's often the first symptom of failing ignition coils, so get that checked out also.

200.mph

iTrader: (9)

a big pry bar will fix your cat, save you money, engine health, and gain power all for free

UnknownJinX

If you suspect a blockage in the cat, take it off and inspect it physically.

It likely has melted or damaged otherwise if it's throwing a code.

And like mentioned, change your ignition components if the history is not known.

200.mph

iTrader: (9)

when in doubt smash it out. cats are only good for chinese food and baiting coyotes

UnknownJinX

It's all fun and games with popping flames until the smell gets lame.

Also, you gotta have something on hand for places with inspections.

200.mph

iTrader: (9)

NotAPreppie

Adding additional flammable hydrocarbons to a flammable hydrocarbon is not going to do much in the exhaust stream.

Assuming any of the laquer thinner makes it to the cat uncombusted, whether it does anything will depend on the cause of the problem. If your cat is clogged because the matrix is mechanically failing (disintegrating, melting, etc) then it's not going to help (and may even accelerate the failure process). In theory, it could help if the cat is just coked up with ash but I really doubt it.

furansu

Yep. Showing up to the office smelling like a Jiffy-Lube tech is not fun. Also since the de-cat, I don't do math so well.

swoope

iTrader: (5)

my kitty sitting next me thinks your an ***. but i lmao!

beers

200.mph

iTrader: (9)

seriously i hate those ********

UnknownJinX

Probably a good thing since aftermarket cats that can live in the RX-8 exhausts are all very expensive. If you can't do math too well, then it doesn't hurt as much when you fork the money over.

Ignorance is bliss.

CaymanRotary

Just an update. Turned out to actually be a fault in the brand new O2 sensors so have to get a new set shipped back for me (Sigh... another $300...). The cat is actually in great condition surprisingly my mechanic referred it as one of the best cats hes seen on a used RX8. So, not gonna try it but if someone does, I would like to know how it goes because I am premixing in the other RX8 (Only 4oz per 10 gallon fillup because still has Cat). If it ever became clogged would like to know if it works. Thanks for the help everyone!

Loki

iTrader: (1)

That doesn't super add up. What is the actual error code you're seeing, and why do BOTH sensors need to be replaced? One of them is before the cat and has nothing to do with most cat codes.

On top of that, if replacing the O2 sensors didn't fix the problem, I would bet dollars to donuts that the O2 sensors are not the problem.

Further, is it possible what's actually failing are your ignition coils and you're getting an emissions code because you're not burning most of the fuel?

"One of the best cats" is a very strange statement. It's like saying "one of the best frying pans". It's fine and looks fine, until it's not. There is nothing to indicate that it's in exceptionally good shape, unless the ones he's comparing to are destroyed.

UnknownJinX

Another thing worth asking then: is it an OEM cat in there?

OEM looks like this:



Rust on the outside is normal, but the shape should be the same.

CaymanRotary

Loki,

"That doesn't super add up. What is the actual error code you're seeing, and why do BOTH sensors need to be replaced? One of them is before the cat and has nothing to do with most cat codes."

The O2 Sensors I had tested and they came back with bad readings. The code shows an error in both Bank 1 and 2 and both sensors when tested were throwing unusual readings.

"Further, is it possible what's actually failing are your ignition coils and you're getting an emissions code because you're not burning most of the fuel?"

Impossible, compression is bang on after they were replaced 3 months ago (replaced coils, spark plugs and wires) and the car freely revs to redline and provides as much power as it should be providing. Car fuel milage bang on 17 MPG (city) and no codes for any ignition problems just a code for Bank 1 and 2 Sensors.

"One of the best cats" is a very strange statement. It's like saying "one of the best frying pans". It's fine and looks fine, until it's not. There is nothing to indicate that it's in exceptionally good shape, unless the ones he's comparing to are destroyed."

I think he meant just physical condition. Not a speck of rust or even a scratch. Cat looks like it just rolled out of the factory from Mazda. Yes it is OEM.

CaymanRotary

@Loki,

"That doesn't super add up. What is the actual error code you're seeing, and why do BOTH sensors need to be replaced? One of them is before the cat and has nothing to do with most cat codes."

The O2 Sensors I had tested and they came back with bad readings. The code shows an error in both Bank 1 and 2 and both sensors when tested were throwing unusual readings.

"Further, is it possible what's actually failing are your ignition coils and you're getting an emissions code because you're not burning most of the fuel?"

Impossible, compression is bang on after they were replaced 3 months ago (replaced coils, spark plugs and wires) and the car freely revs to redline and provides as much power as it should be providing. Car fuel milage bang on 17 MPG (city) and no codes for any ignition problems just a code for Bank 1 and 2 Sensors.

"One of the best cats" is a very strange statement. It's like saying "one of the best frying pans". It's fine and looks fine, until it's not. There is nothing to indicate that it's in exceptionally good shape, unless the ones he's comparing to are destroyed."

I think he meant just physical condition. Not a speck of rust or even a scratch. Cat looks like it just rolled out of the factory from Mazda. @UnknownjinX Yes it is OEM.

Loki

iTrader: (1)

Alright... I'm not convinced because there isn't really a bench test for O2 sensors (outside of a manufacturer's lab). I don't see how they could be tested. If they're showing irregular readings, it's possible the readings actually are irregular. And the odds that both of the old ones and both of the new ones are bad are pretty miniscule. More likely something common to both those sensors is causing this.

Can you share what the actual code is/are?

About the cat... he inspected the inside of it, right? Right?

CaymanRotary

I'm glad you asked me to check this out. I actually just went to the mechanic and the lady that was reporting this information to me was wrong. Turns out the rear o2 sensor is working correctly it is the p0130 bank1 sensor 1 that is throwing the code (Front o2 Sensor). He did remove the cat and no damage was observed either inside or outside the cat. He is absolutely convinced its the sensor because he checked wiring and it is not providing the correct electrical resistance to the sensor. He can't know 100% but I don't really want to take both my cars there just to try to swap the sensors over at cost. Also, I hate dealing with o2 sensors and don't want to try to do this on my own.