Symptoms of cats blowing

[speedy0339]

Just wondering what the symptoms are of my cats blowing. I have ultra on stock cats and I currently have a misfire in 1 cylinder and my exhaust all of a sudden sounds completely different. Is this the beginning of my cats blowing? Hasn't thrown any codes yet so I am not sure.

[s4matty]

Check your exhaust tips for a grey carbon color is a good place to start

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[speedy0339]

Check your exhaust tips for a grey carbon color is a good place to start

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Like this?

[bhvrdr]

Yup you got all the symptoms nailed.

[speedy0339]

1. Will it hurt the car to drive it still?
2. Does Audi still have to honor the cat warranty if I'm TD1?
3. Are HFC good enough to handle ultra or do I have to go test pipes?

[bhvrdr]

1. Will it hurt the car to drive it still?
2. Does Audi still have to honor the cat warranty if I'm TD1?

1. I dont know how long you can consistently misfire but it's probably not good. I would address it.
2. Absolutely not. There is no question a dual pulley tune is at least partially responsible for any cat failures we would have. The egts start to get very high at higher pulley ratios over around 3.15pr
3. No I don't know of any hfc that are likely to be even as,durable as the stock cats. I would hollow the stockers and run a hfc under the car where it will get less hot exhaust and can be easily replaced once it blows again.

Mike

[4Rings3Liters]

While on the topic are the cats in the downpipes or easier to get to than them?

[waxxonMTL]

1. I dont know how long you can consistently misfire but it's probably not good. I would address it.
2. Absolutely not. There is no question a dual pulley tune is at least partially responsible for any cat failures we would have. The egts start to get very high at higher pulley ratios over around 3.15pr
3. No I don't know of any hfc that are likely to be even as,durable as the stock cats. I would hollow the stockers and run a hfc under the car where it will get less hot exhaust and can be easily replaced once it blows again.

Mike

I didn't follow the latest devl. on the subject, but did someone was able to install cat toward the cat back where it was easier to change ?

No aftermarket ever came close to reproduce the HFC of the stock one either right ?

[bhvrdr]

I didn't follow the latest devl. on the subject, but did someone was able to install cat toward the cat back where it was easier to change ?

No aftermarket ever came close to reproduce the HFC of the stock one either right ?

Any exhaust shop can weld or clamp in a HFC downstream. This is easy peasy. You need to source some o2 sensor extenders but that shouldnt be hard.


As far as aftermarket HFC, i'm not sure any out there even qualify. I believe our cats are 400cpsi but they are huge. There may be some 200cpsi options out there for us but I bet they are also about half the surface area of our stock cats so it begs the question, why bother? Add to that even someone who installed uber high quality HJS cats blew them out too so durability at these high of egts we see would also be a concern. I dont know of any HFC out there that are rated upwards of 2192 deg F which is what some of these higher PR cars are seeing ala APR UC or other 187+mm options.

Mike

[AudBoost]

Like this?

That looks like carbon build up.
You will definitely notice a change in exhaust tone when the cats start to go. The sound is very noticeable. When getting on the gas it sounds like a loud hum from the exhaust.
My JHM HFC's blew last week and this is what my tips looked like. You can see on the bumper where I ran my finger through the dust how white-ish grey it is.

[VtotheJ]

How common is the cat issue? On stock S4's?

[bayonet14]

1. Will it hurt the car to drive it still?
2. Does Audi still have to honor the cat warranty if I'm TD1?
3. Are HFC good enough to handle ultra or do I have to go test pipes?

get the euro coded cats - further downstream w/require longer harness for o2 sensors. They are blown .... if you are already DP stg2 go test pipes as you will pick up about another 15/20hp
and major labor to replace anyway.

Have my oem cats if you want - PM for price/shipping

[whiped]

If you start your car in the morning and it sounds like it's cammed you might have cat problems.

[waxxonMTL]

things with test pipe is that they sound loud.. so no good if you want to stay stealth..

[LittleDozer]

If anyone needs some cats in near perfect condition with only 30k miles on them, shoot me a PM. I took mine off for headers before they had any issues, no melted honeycomb.

[bayonet14]

things with test pipe is that they sound loud.. so no good if you want to stay stealth..

Not much louder w/the X-pipe mod I had already done ;)

[q5 dave]

I have ultra on stock cats

Does Audi still have to honor the cat warranty if I'm TD1?

[JetG0ld]

Crown motorsports sells HFC and test pipe options at a pretty affordable price. I've seen a lot of people review them in the b8/8.5 network group on facebook with good results. I'm reluctant as I've got AWE track exhaust with non-res downpipes, and the pipes make it INSANELY loud.

[dave1078]

1. I dont know how long you can consistently misfire but it's probably not good. I would address it.
2. Absolutely not. There is no question a dual pulley tune is at least partially responsible for any cat failures we would have. The egts start to get very high at higher pulley ratios over around 3.15pr
3. No I don't know of any hfc that are likely to be even as,durable as the stock cats. I would hollow the stockers and run a hfc under the car where it will get less hot exhaust and can be easily replaced once it blows again.

Mike

So if I don't want to buy some new cats, I'd best go with 57mm/180mm? (or so)

[cspcrx]

is a stock exhaust car on Test pipes loud as well or is only loud if you have an aftermarket exhaust on the car? I know it would be "louder".

[bhvrdr]

I wouldn't say you'll be immune from it but yeah at 180/57 You stand a better chance of getting some more life out of them than those higher ratios

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[speedy0339]

I think stock exhaust with test pipes would be louder than test pipes with awe resonated downpipes and exhaust for instance.

- - - Updated - - -

Would it be bad to have my local exhaust shop cut the stock cats out and just have a broke boy test pipe basically? Why pay for test pipes?

[bhvrdr]

I think stock exhaust with test pipes would be louder than test pipes with awe resonated downpipes and exhaust for instance.

- - - Updated - - -

Would it be bad to have my local exhaust shop cut the stock cats out and just have a broke boy test pipe basically? Why pay for test pipes?

I wouldnt pay for them. I'd rag on the car hard as hell and hope to blow them out clean and if they dont i'd hollow the OEM ones out.

Mike

[JetG0ld]

I wouldnt pay for them. I'd rag on the car hard as hell and hope to blow them out clean and if they dont i'd hollow the OEM ones out.

Mike

I've seen talk of failed motors due to plugged cats. Are you able to hollow out the OEM cats without having to remove the pipe from the car? If not, I'd just spend a couple hundred and get some actual test pipes, as its a very labor intensive job.

[speedy0339]

My local exhaust shop said they won't cut the cats out because it's against EPA law :/

[kelseysautobody]

My local exhaust shop said they won't cut the cats out because it's against EPA law :/

Time to find a new exhaust shop

[speedy0339]

Are the cats far enough back that an exhaust shop can get a saw in to it them out?

[mgert31907]

Are the cats far enough back that an exhaust shop can get a saw in to it them out?

The cats are not far enough out to saw them out. What people are recommending you do is hollow them out and then have HFC's put in the exhaust flow after the OEM stock cats, somewhere down the line.

It goes like this. Engine->exhaust-manifold->catylitic-converter->exhaust. That is the basic flow of where you cats live. They are buried deep between the exhaust manifold and exhaust. Hope this helps.

[speedy0339]

The cats are not far enough out to saw them out. What people are recommending you do is hollow them out and then have HFC's put in the exhaust flow after the OEM stock cats, somewhere down the line.

It goes like this. Engine->exhaust-manifold->catylitic-converter->exhaust. That is the basic flow of where you cats live. They are buried deep between the exhaust manifold and exhaust. Hope this helps.

So what's the easiest way to get the hallowed out? If you can't do it without taking them out, it's probably better to get test pipes once it's the same labor.

[bayonet14]

So what's the easiest way to get the hallowed out? If you can't do it without taking them out, it's probably better to get test pipes once it's the same labor.

get TPs - you can either drop the entire sub frame - but if your DSG - drop the tranny... should be 800/900 bucks in labor

[fitzydude]

I wouldnt pay for them. I'd rag on the car hard as hell and hope to blow them out clean and if they dont i'd hollow the OEM ones out.

Mike

When my cats start failing, which is some kind of miracle they havent yet, im going to remove my downpipes and use something to hammer remaining cat material out while still in the car. The trick will be finding something flexible yet rigid enough to get up there. Ill install O2 spacers at that point and be on my way.

[speedy0339]

APR has a tune update that gets rid of the check engine light for no cats, so I don't care about the O2 seniors. But the labor is what sucks for the test pipes.

[jimrobbington]

This is how you do it on a B7 anyway...

https://youtu.be/lXD7Hj5TrhE

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[B8 S4]

Not looking forward to possible failing cats once I install my 189mm crank pulley. I wouldnt mind the test pipe idea at all if it wasnt such a bitch to install.

[speedy0339]

Not looking forward to possible failing cats once I install my 189mm crank pulley. I wouldnt mind the test pipe idea at all if it wasnt such a bitch to install.

Yeah I don't really care about needing test pipes but the labor is a bitch. And it sounds like absolute shit

[mgert31907]

Yeah I don't really care about needing test pipes but the labor is a bitch. And it sounds like absolute shit

Take a peak in the mertop headers thread. Installing long tube headers on these cars is way past nightmare status. I will eventually get around to it, but will have to take my time as 💻 sci degree and full time work takes up so much time.

[speedy0339]

Take a peak in the mertop headers thread. Installing long tube headers on these cars is way past nightmare status. I will eventually get around to it, but will have to take my time as 💻 sci degree and full time work takes up so much time.

The headers are what the test pipes connect to. I'm only doing the pipes, not the headers. Headers are another $2500.

[bayonet14]

APR has a tune update that gets rid of the check engine light for no cats, so I don't care about the O2 seniors. But the labor is what sucks for the test pipes.

It does suck - but I am glad I went test pipe route and the program map for the APR DP Ultra for CEL was surprising / throttle response and top end was wow. But I a upgrading my exhaust to a AWE touring w/their resonated down pipes. I'll need to make another vid now w/test pipes...

[speedy0339]

It does suck - but I am glad I went test pipe route and the program map for the APR DP Ultra for CEL was surprising / throttle response and top end was wow. But I a upgrading my exhaust to a AWE touring w/their resonated down pipes. I'll need to make another vid now w/test pipes...

Yes please post a video! I have track with resonated downpipes but at least I'll get an idea of what it's going to sound like.

[TheAsset]

It has been amusing to say the least.