[Sleeper340i]

So I've recently been running MHD stage 2 with an ER high flow down pipe, along with an AP Intake for the last few months. I started doing "high" settings for my pops and it was only a month before my pops disappeared completely for no reason. Then a boost leak came about a month later after the disappearing pop issue. It was under boosting from target PSI by about 3-4. With the help of some people on these forums (special thanks to those who helped) and a few Indy shop visits, I finally took off the down pipe with a friend and looked at my cats two days ago, as a last culprit before my turbo.

The cat was not even in place, and was all the way on the other end of the down pipe! I somehow managed to melt it with the popping, and got it to form into a concentrated ball, which flung to the other side. So we removed the O2 sensor and flipped the down pipe to the side and the cat just plopped right out.

After removal of the melted cat, the car runs and breathes way better than it has ever been. I can hear the turbo spool louder, the car shifts like butter, the loudness is perfect(minus the cold start) and man the smell is not as bad as I thought it would be. You can smell it occasionally with windows down but it's not much to annoy me, and the best part is it feels like I gained around 75-100 horsepower. Honestly the car feels much faster now being catless when compared to when I first got the high flow down pipe. I spin in first and second gear now which I never did much, even with crappier tires with the high flow down pipe. I'm a big fan of cat less now and anyone with high flow down pipes be advised, these things can be fragile.

TL;DR
Melted my high flow cat within a month from high popping which caused me to lose drastic power and have a boost leak, also made my car feel sluggish and off. After removal, car is running even better than when i had the brand new high flows on.

[johnung]

Originally Posted by Sleeper340i

So I've recently been running MHD stage 2 with an ER high flow down pipe, along with an AP Intake for the last few months. I started doing "high" settings for my pops and it was only a month before my pops disappeared completely for no reason. Then a boost leak came about a month later after the disappearing pop issue. It was under boosting from target PSI by about 3-4. With the help of some people on these forums (special thanks to those who helped) and a few Indy shop visits, I finally took off the down pipe with a friend and looked at my cats two days ago, as a last culprit before my turbo.

The cat was not even in place, and was all the way on the other end of the down pipe! I somehow managed to melt it with the popping, and got it to form into a concentrated ball, which flung to the other side. So we removed the O2 sensor and flipped the down pipe to the side and the cat just plopped right out.

After removal of the melted cat, the car runs and breathes way better than it has ever been. I can hear the turbo spool louder, the car shifts like butter, the loudness is perfect(minus the cold start) and man the smell is not as bad as I thought it would be. You can smell it occasionally with windows down but it's not much to annoy me, and the best part is it feels like I gained around 75-100 horsepower. Honestly the car feels much faster now being catless when compared to when I first got the high flow down pipe. I spin in first and second gear now which I never did much, even with crappier tires with the high flow down pipe. I'm a big fan of cat less now and anyone with high flow down pipes be advised, these things can be fragile.

TL;DR
Melted my high flow cat within a month from high popping which caused me to lose drastic power and have a boost leak, also made my car feel sluggish and off. After removal, car is running even better than when i had the brand new high flows on.

I've read a bunch of warnings about not setting burbles and pops too high or it can damage the catalytic converter over time. Yours is the fastest I've ever heard. I wonder if it was somehow defective to begin with?

I also wonder about the efficiency of the high flow cats. I suspect that most aren't very efficient or they would have numbers. The exception that I know of is the Fabspeed HJS catted downpipe that I run. They dyno'd their catted versus their catless and it came in at 93%, which is amazing especially considering it's guaranteed not to throw a Check Engine Light.

[BMWILUVU]

Originally Posted by johnung

I've read a bunch of warnings about not setting burbles and pops too high or it can damage the catalytic converter over time. Yours is the fastest I've ever heard. I wonder if it was somehow defective to begin with?

I also wonder about the efficiency of the high flow cats. I suspect that most aren't very efficient or they would have numbers. The exception that I know of is the Fabspeed HJS catted downpipe that I run. They dyno'd their catted versus their catless and it came in at 93%, which is amazing especially considering it's guaranteed not to throw a Check Engine Light.

Burbles are also not very good for turbos.

[jbb2388]

I just don't get the fascination of "pops" and "burbles". They sound absolutely ridiculous to me and clearly cause more trouble then they're worth.

[Supr3me]

Originally Posted by BMWILUVU

Burbles are also not very good for turbos.

I don't not believe you, but I'm really surprised to hear this. BMW introduced the burbles with their MPPSK and they tend to be very conservative.

[kern417]

Originally Posted by Sµpreme

I don't not believe you, but I'm really surprised to hear this. BMW introduced the burbles with their MPPSK and they tend to be very conservative.

The concept of burbles will damage it but the speed depends on the application. In the MPPSK case it's pretty minor but still not ideal. It wastes gas, creates high cylinder/exhaust pressures when it's not needed, and increases EGTs. Now realistically that probably means the turbo will only last 100k vs 110k (arbitrary numbers) but who knows.

What I find crazy is that, when talking about the veloster burbles, Hyundai specifically advertises it as a form of antilag which is known to be VERY damaging and is typically reserved for racing where speed is more important than turbo life and reliability. I think they're pushing for the performance discussion more than "I just like hearing burbles" narrative, but it's really the same.

But as said in another thread, i think its ridiculous that this is such a common issue with BMWs. Burbles or not, there are 700+hp engines with catalytic converters. There's no reason the BMW stock or aftermarket exhaust shouldn't be able to handle a beating.

[mike@x-ph.com]

Im sorry to hear that OP. We always recommend keeping burbles conservative unless you are running a fully catless pipe

[G.Newt]

I was going to say, "You get what you pay for", but I checked the price, and it's $850 for an ER catted downpipe?! That's too close to the price of CG DS-1 (which I have and enjoy) and AA, both of which have no reported cat issues and will not throw a CEL.

Sounds like a possible quality miss on ER's part combined with some abuse from the high burble settings. Even with running a BM3 OTS tune, my much milder burbles don't kick in until a minute or two, presumably when the cat is more warmed up.
The stock BMW tune has very aggressive burbles settings compared with BM3 and I doubt I damaged my cat when I was stock.

[cooolone2]

Not all DP's are equal (obviously)... Is a shame really! Have you contacted the company? Could be just a defective unit, manufacturing allows for a certain % of defect, is why QC exists. Even then things slip through, it happens. I would reach out to them and see what their response is.

[weehe126]

ER makes high quality stuff. I'd contact them as this can't be normal.

[Sleeper340i]

Originally Posted by johnung

I've read a bunch of warnings about not setting burbles and pops too high or it can damage the catalytic converter over time. Yours is the fastest I've ever heard. I wonder if it was somehow defective to begin with?

I also wonder about the efficiency of the high flow cats. I suspect that most aren't very efficient or they would have numbers. The exception that I know of is the Fabspeed HJS catted downpipe that I run. They dyno'd their catted versus their catless and it came in at 93%, which is amazing especially considering it's guaranteed not to throw a Check Engine Light.

Yeah I wasn't considering a manufacturer defect at first, but now that no one mentions they've had an issue with an ER down pipe cat I'm beginning to question it myself. I also read to run I could ruin the cats from pops so I only had the pops on high setting for about two weeks and the rest were either on low or medium. 7 percent different is a pretty damn small margin and sounds about right with a lot of people that say catless and high flow feel the same, but in my case I can definitely tell a difference between catless and high flow for ER. Unless the cats were faulty in the first place lol. I'm Not gonna be quick to point fingers though.

[Sleeper340i]

Originally Posted by jbb2388

I just don't get the fascination of "pops" and "burbles". They sound absolutely ridiculous to me and clearly cause more trouble then they're worth.

Right with you man. Before I got the car, I thought it was obnoxious and not my thing, but it kinda grew on me. I mainly enjoyed it because it's not something you hear often, at least around where I live. But it's enjoyable only for so long before it gets kinda old. I still enjoy occasional small pops here and there though now that they're back.

[Sleeper340i]

Originally Posted by kern417

The concept of burbles will damage it but the speed depends on the application. In the MPPSK case it's pretty minor but still not ideal. It wastes gas, creates high cylinder/exhaust pressures when it's not needed, and increases EGTs. Now realistically that probably means the turbo will only last 100k vs 110k (arbitrary numbers) but who knows.

What I find crazy is that, when talking about the veloster burbles, Hyundai specifically advertises it as a form of antilag which is known to be VERY damaging and is typically reserved for racing where speed is more important than turbo life and reliability. I think they're pushing for the performance discussion more than "I just like hearing burbles" narrative, but it's really the same.

But as said in another thread, i think its ridiculous that this is such a common issue with BMWs. Burbles or not, there are 700+hp engines with catalytic converters. There's no reason the BMW stock or aftermarket exhaust shouldn't be able to handle a beating.

Yes exactly why I'm going to leave it in OEM setting for now. I want my turbo to last and more gas is always nicer. Now that my boost leak is gone though I finally was able to check my boost today (didn't have my android phone) and my boost is over boosting? I was hitting around 18.2- 21.7 PSI when my target was 15.7 PSI. I know 22 PSI is what has blown some people's turbos and with the cold weather idk if it's a good mix. Maybe I'll take it easy with this cold weather for safety for my turbo. Trying to have it lasts for few a more months at least before I upgrade.

[Sleeper340i]

Originally Posted by G.Newt

I was going to say, "You get what you pay for", but I checked the price, and it's $850 for an ER catted downpipe?! That's too close to the price of CG DS-1 (which I have and enjoy) and AA, both of which have no reported cat issues and will not throw a CEL.

Sounds like a possible quality miss on ER's part combined with some abuse from the high burble settings. Even with running a BM3 OTS tune, my much milder burbles don't kick in until a minute or two, presumably when the cat is more warmed up.
The stock BMW tune has very aggressive burbles settings compared with BM3 and I doubt I damaged my cat when I was stock.

Yeah you would think paying an extra 4-5 hundred for a high flow cat, you'd expect it to be good quality and last but nope.

Interesting you mention BM3 Burble is less than BMW's. Were you running a high flow or catless along with BM3? Now that I'm running catless on MHD "OEM" Burble settings, this thing still pops quite loud when pushed. Wasn't expecting one, but got my first pop in months actually and almost became deaf doing it in a tunnel from a half second pull earlier lol.

Crazy how much of a difference in spool noise and pops high flow vs catless makes.

[Sleeper340i]

Contacted ER earlier, will update as soon as I hear a response as to what they say about this issue.

[johnung]

Originally Posted by Sleeper340i

Yeah I wasn't considering a manufacturer defect at first, but now that no one mentions they've had an issue with an ER down pipe cat I'm beginning to question it myself. I also read to run I could ruin the cats from pops so I only had the pops on high setting for about two weeks and the rest were either on low or medium. 7 percent different is a pretty damn small margin and sounds about right with a lot of people that say catless and high flow feel the same, but in my case I can definitely tell a difference between catless and high flow for ER. Unless the cats were faulty in the first place lol. I'm Not gonna be quick to point fingers though.

Only way to tell the real difference between a certain catted vs catless is a dyno. I believe Fabspeed's 93% number because they are using HJS cats which are known to be the best. But I haven't seen any dyno numbers from any other catted downpipe manufactures so I suspect that their performance numbers aren't as good.

[Skyhigh]

Is it known what cat converter the DP features? Most (good) DP manufacturers use HJS cat converters (Akrapovic, AC Schnitzer, etc). I seriously doubt this one was HJS, as I have never heard about issues with it.

This said, increases pops and bangs certainly contributed, but still... Never seen anything like this before! Have you ran your big bang theory settings with the original DP before? I suspect it is a different quality, even if more restrictive...

[jackstrath]

your lucky you didnt blow the valve stem seals or the turbo oil seals as well tbh, the back pressure would of been mega high!

[kern417]

Had time to think about it, and I feel like it's the downpipe design. Most cats are in a section of pipe that is significantly wider diameter than the rest of the pipe. I suspect this helps hold it in place, vs ER design that is basically a straight through tunnel where the only thing holding the cat are the welds. Not 100% sure, but I'd suspect it makes sense.

The actual cat type shouldn't make a difference. HJS is a good name but in reality they're all pretty much the same except the cell count. That won't factor into it staying in the pipe.

[jbb2388]

Originally Posted by Sleeper340i

Right with you man. Before I got the car, I thought it was obnoxious and not my thing, but it kinda grew on me. I mainly enjoyed it because it's not something you hear often, at least around where I live. But it's enjoyable only for so long before it gets kinda old. I still enjoy occasional small pops here and there though now that they're back.

I'm loving my tune with zero pops and bangs. Sorry for your troubles man. Hope you get everything straightened out quickly.

[Skyhigh]

Originally Posted by kern417

Had time to think about it, and I feel like it's the downpipe design. Most cats are in a section of pipe that is significantly wider diameter than the rest of the pipe. I suspect this helps hold it in place, vs ER design that is basically a straight through tunnel where the only thing holding the cat are the welds. Not 100% sure, but I'd suspect it makes sense.

Your main problem is not that it detached. Your problem is it MELTED! It would have melted even if it was "stuck" in place. It detached because it melted, it did not melt, because it detached....

Converters falling apart is a common thing.... typically after 3-400 000 km. But they normally don't melt.

The actual cat type shouldn't make a difference. HJS is a good name but in reality they're all pretty much the same except the cell count. That won't factor into it staying in the pipe.

The quality of the cat converter makes all the difference! Remember that its primary role is to convert exhaust gases to a level satisfying specific environmental standards. One cat converter achieves Euro 6 with a 500 cell design, another with a 200. How do you think that works? It works by using different (more expensive) materials in order to boost the efficiency whilst reducing the cell count. So no - cat converters are not all the same. Which is why you also don't have that many companies to manufecture them I reckon. It is not really a backyard task I suspect.

Another question - are you losing coolant? I just remembered that a freind of mine destroyed both his DPF and the cat converter (melted) because his engine was burning coolant (cracked cylinder head).

[kilogram]

This isn't surprising at all, tbh. Dumping unburned fuel through any cat will shorten its lifespan because its operating temps will skyrocket just trying to do its job. This is partly why test pipes became a thing- running excessively rich with lots of WOT on track back when OEMs tended to run turbo cars in the 0.7-0.75 range under load would kill the cat pretty quickly.