The Official Blown Catalytic Converter Thread

[drew_doc1]

Have JHM test pipes w AWE touring exhaust w resonated DP's. Was pretty loud and the odor was rough. I found the best price for GESI Vibrant high performance cats online at Home Depot of all places. Had custom install just infront of the x-pipe w quick change flanges in case they need to be replaced in the future. No smell now, slight reduction in noise, and likely a slight bit to the power, but for me was worth it.

[iamrc16]

So looks like I have a failed cat also @52k stage 2 single pulley and tcu tune. I went in to Audi Friday and was told scans were still reading my tune so they supposedly unplugged right away before signal sent thru. My question for all my tuned ppl is should I have tcu tune flashed back to stock also? I was told to give it a week or so to come back to Audi and try again with the scan from my SA so I will be most likely returning this week

[WillS4]

Why do the test pipes get ceramic coated? For sound?

[ModItNow]

Why do the test pipes get ceramic coated? For sound?

For heat dissipation

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[gsxr_wrx]

Anyone ever test the magnaflow oem test pipes? If so, how’s the longevity

[audis4culver]

Mystery smell help. 2011 Audi S4 Stage 2 with AWE touring exhaust. So this summer has been over the top hot and I have been driving my yard car instead of the s4. I keep the car in a very sealed enclosed garage. two weekends ago I drove it early in the morning when the temps were lower and with windows open, I smelled a very strange dead animal or sulfurish smell from the right side the with windows open. The smell does not happen when the car is turned off. so I am thinking its not actually a dead animal.... is this smell the beginning of a cat going bad? The car sat for 2 months with very minimal use and now this smell has appeared. I dont see any white residue on the exhaust or back of car. The smell wont go away and its pretty bad. If the cats are going, is this a 2K job or 4k ? If they are going, can I keep driving until the next inspection? This post people report a sulfur smell - is the smell straight up sulfur or are other smells mixed in - like a gas or dead animal type smell? I dont smell it when the car is idling in the garage, but when I drive and come to the first or second red light it really smells. only smell it with windows open. Thanks.

[Maple Leaf]

Have JHM test pipes w AWE touring exhaust w resonated DP's. Was pretty loud and the odor was rough. I found the best price for GESI Vibrant high performance cats online at Home Depot of all places. Had custom install just infront of the x-pipe w quick change flanges in case they need to be replaced in the future. No smell now, slight reduction in noise, and likely a slight bit to the power, but for me was worth it.

Any chance you have pics of this setup? Also curious how sound compares to stock cats with AWE touring and resonated DP's as this is my setup now and in planning for the eventual failure, your setup sounds similar to something I might want to do.

[mys4.org]

Is the cats from a b8 and b8.5 the same? Sorry I'm have no luck searching

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[Rodizzle]

Is the cats from a b8 and b8.5 the same? Sorry I'm have no luck searching

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Not the same but they are interchangeable . The 02 sensor is just slightly in a different location .


B8.5 034 E40 DP

[jparedes]

I’m getting my engine cradle / subframe replaced and also my engine mounts since they will be accessible. Are the cats going to be more accessible during this process? If so I might just ask my shop to go ahead and install test pipes or I’ll buy some used cats and gut them ahead of time. Then I’ll install high flow cats in the down pipe.

[harrisonk8]

2013 s4 79.5k. Got a 420 code couple months back, dealer did the reflash. I scanned the car a couple weeks back and saw the 420 as a soft code, didn't set off the engine light. After two hard pulls merging onto highway last Friday, the check engine light came on. Bringing the car to dealer tomorrow. Hopefully they cover with no issues.

[jparedes]

So i'm looking for the best high flow internal metallic cats in terms of rated for highest EGT's to install in my down pipes after I gut my cats. I can't get any help from the Magnaflow reps on giving me specs it's like they are worried that if it's in an e-mail they are liable if something happens or something. I think i've read that we can get up to 1800 F in the stock location so i'll just assume that it might be close to that even at the down pipes to be conservative. Anyone have any good suggestions?

[JoedreddUK]

So i'm looking for the best high flow internal metallic cats in terms of rated for highest EGT's to install in my down pipes after I gut my cats. I can't get any help from the Magnaflow reps on giving me specs it's like they are worried that if it's in an e-mail they are liable if something happens or something. I think i've read that we can get up to 1800 F in the stock location so i'll just assume that it might be close to that even at the down pipes to be conservative. Anyone have any good suggestions?

I believe the GESI is up to 2500f


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[tgsweat]

So i'm looking for the best high flow internal metallic cats in terms of rated for highest EGT's to install in my down pipes after I gut my cats. I can't get any help from the Magnaflow reps on giving me specs it's like they are worried that if it's in an e-mail they are liable if something happens or something. I think i've read that we can get up to 1800 F in the stock location so i'll just assume that it might be close to that even at the down pipes to be conservative. Anyone have any good suggestions?

I have the magnaflows in my downpipes. I think that 1800F is for the coating that actually does the emissions work. They won't melt until around 2500F or so. Mine are holding up fine structurally/hasn't melted, but i'm pretty sure the coating is gone because i get more gas smell than i did when i first put them on. Which makes sense because i see around 1050C-1100C EGT on a long pull...which i do often lol

That being said, i'm going to put in the new GESI ($135) cats which are 300cel vs 200 of the magnaflow and see if i can cut the smell even more. GESI said theirs are good up to 1900F for the coating and 2500F for melting.

[jparedes]

I have the magnaflows in my downpipes. I think that 1800F is for the coating that actually does the emissions work. They won't melt until around 2500F or so. Mine are holding up fine structurally/hasn't melted, but i'm pretty sure the coating is gone because i get more gas smell than i did when i first put them on. Which makes sense because i see around 1050C-1100C EGT on a long pull...which i do often lol

That being said, i'm going to put in the new GESI ($135) cats which are 300cel vs 200 of the magnaflow and see if i can cut the smell even more. GESI said theirs are good up to 1900F for the coating and 2500F for melting.

Man those are higher EGT's than the 1800 deg F that I thought were max possible. So more like 2000 deg F.... FML. How long did the magnaflows last before they started stinking? Are you running gutted cats or test pipes?

Did those numbers apply for the $135 cats? When I look at their website, https://gsportbygesi.com/high-perfor...tems-products/, they don't list any specs for HP ratings for the 10025 P/N cats which I believe are the ones you're referring to.

[tgsweat]

Man those are higher EGT's than the 1800 deg F that I thought were max possible. So more like 2000 deg F.... FML. How long did the magnaflows last before they started stinking?

Did those numbers apply for the $135 cats? When I look at their website, https://gsportbygesi.com/high-perfor...tems-products/, they don't list any specs for HP ratings for the 10025 P/N cats which I believe are the ones you're referring to.

Yeah i only get that high on a quarter mile pull. Usually i'll hit around 975 or so on some spirited driving around town. But yeah these cars run hot. Also these are calculated numbers, so who knows what we are actually seeing further away in the downpipe. I've had the magnaflows on since july and i noticed more gas smell around november or so. The smell never went completely away after installing these. As of today, the smell is still a lot better than no cats at all. Just wanting to check out how they are holding up and try the new GESI cats. Its easy to swap when they are in the downpipes.

Yes those numbers apply for the $135 ones also. I called them up myself. The only difference between the $135 and $350 ones is the coating. There more of the precious metal coating on the more expensive ones to pass EPA emissions standards. GESI told me that if you aren't using these to pass emissions, then the $135 ones will do the job for cutting smell and helping with sound.

[jparedes]

Yes those numbers apply for the $135 ones also. I called them up myself. The only difference between the $135 and $350 ones is the coating. There more of the precious metal coating on the more expensive ones to pass EPA emissions standards. GESI told me that if you aren't using these to pass emissions, then the $135 ones will do the job for cutting smell and helping with sound.

That's good to know. I'm not even looking to pass inspection I just want to A) be able to replace them easily so that's why they'll be in the down pipes. B) reduce gas smell when i go gutted OEM cat. and C) find the highest temp rated so they don't clog and cause me to blow a motor. I'll turn off the CEL via the tune and deal with passing inspection a different way.

D) Making the sound better is going to be there regardless of brand just by the fact that it's slowing down the exhaust.

I'm also thinking of getting them with the O2 sensor port bung that I would cap off with a threaded cap so that I can periodically open them up and inspect them with a boroscope to see how they are doing.

[tgsweat]

That's good to know. I'm not even looking to pass inspection I just want to A) be able to replace them easily so that's why they'll be in the down pipes. B) reduce gas smell when i go gutted OEM cat. and C) find the highest temp rated so they don't clog and cause me to blow a motor. I'll turn off the CEL via the tune and deal with passing inspection a different way.

yep i gutted my cats and got a spacer. Still passes inspection here in MD. The magnaflow is going to be the cheapest but gets the job done for what you need. I'm pretty sure magnflow had a lower rating for the coating than the GESI, just can't remember the exact number when i called. As far as clogging, you should be good with either. I'm having the GESI installed on friday, so i can let you know what my magnaflows look like when they are out.

[jparedes]

What was the part number on the magnaflow cats you used? Someone has a set of 59906's for sale on here (which is what I was trying to get specs for from magnaflow) The magnaflow rep said "These are intended to be replacement OE converters. They are not performance based or "high flow" converters, they are strictly intended to be a OE replicated replacement component that have the same tolerance as that of a factory part."

[tgsweat]

I have the 59955. Got them for $75 each back in july.

[jparedes]

Question: I have a B8.5. Will I have any issues with clearance or fitment against the firewall or anything if I try to use B8 cats with vibrant 11619 o2 J spacers?

[BoltMan]

15k miles on Dual pulley with crackles and so far the cats seem to be doing alright. Hoping they stay like this, otherwise it might be time for some GESI units

[Audibellybutton]

Almost positive my cats are blown. Got catalyst codes for bank 1 and 2 and my car is dual pulley. Had a leaking valve cover gasket on both sides so I think burning oil burned the cats out faster. Only question is did the cats blow outward themselves? Both my exhaust tips are ashy white and a lot of white smoke blew out under throttle I’m just wondering did they gut themselves? The exhaust gas smells stronger and I do get that sulphuric smell too. Should I keep stepping on it until all the ashy white dust is gone or is that a bad idea?

[Audibellybutton]

Almost positive my cats are blown. Got catalyst codes for bank 1 and 2 and my car is dual pulley. Had a leaking valve cover gasket on both sides so I think burning oil burned the cats out faster. Only question is did the cats blow outward themselves? Both my exhaust tips are ashy white and a lot of white smoke blew out under throttle I’m just wondering did they gut themselves? The exhaust gas smells stronger and I do get that sulphuric smell too. Should I keep stepping on it until all the ashy white dust is gone or is that a bad idea?

Update I really think they might have blown themselves out and I might be lucky. The exhaust smells a lot more rich now just like when I had catless downpipes on my amg and there’s no more white smoke just some black smoke at high rpm. I’m
Thinking of renting a plumbing camera to confirm

[street2gen]

Update I really think they might have blown themselves out and I might be lucky. The exhaust smells a lot more rich now just like when I had catless downpipes on my amg and there’s no more white smoke just some black smoke at high rpm. I’m
Thinking of renting a plumbing camera to confirm

Mine, was melting in on itself and throwing epc light it looked pretty concerning.... i would def scope it from the manifold 02 to make sure.

[Jimmy_s4]

So I’ve only had my 2016 s4 for about 5 months now. 21k miles. Looking to tune soon, most likely unitronic stage 3. Has anyone blown their cats with unitronic? I know a tune is a tune so it’ll probably happen but is there anything I can do to prolong my lifetime of my cats. In NY they don’t do visuals and I see u guys are saying go test pipes. Only worry I have is seeing a lot of posts about cats blowing very quickly and very often with dual pulley tunes

[01northernS4]

So I’ve only had my 2016 s4 for about 5 months now. 21k miles. Looking to tune soon, most likely unitronic stage 3. Has anyone blown their cats with unitronic? I know a tune is a tune so it’ll probably happen but is there anything I can do to prolong my lifetime of my cats. In NY they don’t do visuals and I see u guys are saying go test pipes. Only worry I have is seeing a lot of posts about cats blowing very quickly and very often with dual pulley tunes

+1

haven't seen any myself on unitronic melting cats but I am curious as well

[01northernS4]

Mine, was melting in on itself and throwing epc light it looked pretty concerning.... i would def scope it from the manifold 02 to make sure.

Street2gen and/or anyone that knows, how easy is it to boroscope the cats? probably best to do so before going dual pulley?

I picked up one of those amazon specials that hook up to your phone... do you think scoping from the 1st manifold 02 sensor in the engine is easier than dropping the exhaust and going up from the downpipe?

[Audibellybutton]

So I’ve only had my 2016 s4 for about 5 months now. 21k miles. Looking to tune soon, most likely unitronic stage 3. Has anyone blown their cats with unitronic? I know a tune is a tune so it’ll probably happen but is there anything I can do to prolong my lifetime of my cats. In NY they don’t do visuals and I see u guys are saying go test pipes. Only worry I have is seeing a lot of posts about cats blowing very quickly and very often with dual pulley tunes

I don’t think the tune company matters. They’re gonna go eventually. I’m at 97k miles though. Bought the car with rather high miles and tuned it. At 21k miles I’d say you should have a lot of life left on the cats but just be ready to change them down the road or install test pipes or gut them etc

[street2gen]

Street2gen and/or anyone that knows, how easy is it to boroscope the cats? probably best to do so before going dual pulley?

I picked up one of those amazon specials that hook up to your phone... do you think scoping from the 1st manifold 02 sensor in the engine is easier than dropping the exhaust and going up from the downpipe?

Even IF dropping exhaust was an easier option i would think it could be misleading...... in this picture my cat is melting in on itself and never made it all the way through, if i remember correctly it looked perfectly normal on the other side.
I would pull manifold 02s to be sure.

[jparedes]

Is it pretty easy to get the manifold 02's off to do it?

[01northernS4]

Is it pretty easy to get the manifold 02's off to do it?

+1

for those who have done it or know, how hard is it to get the manifold 02's off to scope the cats?

[Robdukes]

For those curious. Had Audi quote me new cats. 7k. Crazy.

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[SSSSS5]

For those curious. Had Audi quote me new cats. 7k. Crazy.

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Although they are indeed a bitch to replace, they are't a $7,000 bitch. Thats ludacris

[s3lman]

Just took my cats out earlier this week and replaced them with test pipes as I plan on going dual pulley soon. I currently have a custom exhaust (Magnaflow 11385 in place of baby res -> Res delete -> Muffler delete). before I had my cats removed this sounded pretty damn good for a custom route. After I had the test pipes put in this thing sounds horrendous. basically anything above 2700 rpm with the windows up it feels like I'm listening to my car from the outside and with the crackle pop from IE it sounds like actual gunshots I knew it was going to sound horrible but I was just really curious to find out lol. Luckily I have a set of Magnaflow mufflers and tips going on this coming Monday.

[cssullivan]

+1

for those who have done it or know, how hard is it to get the manifold 02's off to scope the cats?

+1 bump

[KnewJack]

Thread Revival.

I got the Cat eff code for Bank 2 last week and the change in exhaust tone. Car feels down on power intermittently which I think means its clogged and not blowing itself out. Full throttle give an misfire code on cyl 6 and EPC so I've been driving it easy. I Plan on trying to gut it this Sunday. Do I need to gut both at the same time? Is one gutted going to be a problem performance wise? Stage 2+.

[SCHOUGY]

if you are making the effort to gut one, then do the other and thank yourself later :)

[mys4.org]

if you are making the effort to gut one, then do the other and thank yourself later :)

Yes very true but one side comes out easy the other (passenger if my memory is correct) is a pain in the a$$ to drop as it doesn't clear the tranny unless you to JHM method and pull the tranny out of the way with a heavy duty strap. Need to a lift to do that.

[BigKeshy]

Yes very true but one side comes out easy the other (passenger if my memory is correct) is a pain in the a$$ to drop as it doesn't clear the tranny unless you to JHM method and pull the tranny out of the way with a heavy duty strap. Need to a lift to do that.

If you're on jack stands/ramps/quick-jack/etc. you can run the heavy duty strap around the bottom of your B-pillar. Just put a towel between the strap and the paint and make sure the ratcheting mechanism is somewhere on the underside of the car so you don't scratch anything up.

It's not ideal the way a lift would be, but it does work and shouldn't cause any instability in the car when it's lifted off the ground.