Diesel exhaust prior to particulate filter and after (photos)

"dieseldub" (dieseldub) 09/19/2019 at 13:48 • Filed to: None

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I’m replacing a failed turbo on a customer’s 2013 Passsat TDI diesel, the car already has 290,000 miles on it. The customer insisted I replace the DPF since the labor to remove it would already be done in the process of replacing the turbo. So I go ahead and order the parts. Likely thanks to dieselgate and the number of cars being fixed to be resold, there is a shortage of new diesel particulate filters (DPF for short) for these cars. I had to wait for one to arrive from Germany. Ordered it in late July and just showed up on Tuesday (9/17).

Anyway, sometimes I just have to stop to admire inventions that do what once upon a time was thought to be near impossible, such as making diesels not belch black smoke.

Photo #1 is the exit from the turbo and into the oxidation cat and DPF:

Typical sooty exhaust, right? Actually, really doesn’t look bad at all for 290,000 miles of accumulation compared to diesels from 15+ years ago . Testament to how good the super high pressures and ability to have much more control over injection events that modern commonrail technology allows.

But that’s not the impressive part. The impressive part is what comes out of the DPF, or more accurately, what isn’t coming out of it:

Pristinely clean exhaust downpipe with 290,000 miles on the car. I never cease to be amazed at how good these work. They have certainly had their growing pains, but at least in VWs case, as they moved on from the gen 1 engines, the reliability of the DPF seemed to increase drastically.

Now if we could only get all of them to be so reliable, we’d have less guys removing these and rolling coal. Diesel emissions controls today are akin to what gas engines had to go through when emissions laws first were enacted in the 70s and on into the 80s. There were a lot of growing pains and poor performing engines which many people then bypassed to gain back reliability and drivability. Given enough time and resources thrown at it, things turn out very well.

This customer keeps meticulous track of his mileage on Fuelly. His lifetime average is 46.6 MPG so far, which is ridiculous for a car this size. Seriously, the 2012 and up Passats are HUGE. You don’t realize just how huge they are until you compare their length with other large vehicles side by side... or just get into the back seat and realize there’s a surprising amount of leg room back there. Getting a lifetime average MPG in the mid 40s with a vehicle this size is crazy.

Neil drives a beetle and a fancy beetle > dieseldub 09/19/2019 at 14:11

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I get frustrated can’t believe  how many 335d cars I see for sale with emissions components removed to reduce maintenance upkeep. 

dieseldub > Neil drives a beetle and a fancy beetle 09/19/2019 at 14:18

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Yeah... they’re also hot rods of the diesel car world in the U.S.. Didn’t sell a ton of them, but holy crap are they fast... and get a lot faster with all the emissions stuff removed.

And being that they were early in the strict diesel emissions era, yeah, they definitely had their reliability issues. Lots of odd NOx codes and the sensors cost stupid amounts of money out of warranty (something like $800... for a frigging sensor ) . Diesel exhaust fluid related codes, carbon build up from the EGR... the list goes on.

Though here in California, it’s not super easy to get away with emissions deletes, so there’s still a lot of them with the equipment intact and they’re getting pretty cheap.

I keep eyeballing them and buyback TDIs coming back to the market. I do really like the “gen 2" engines like what I’m working on here , just a shame that they only came in 2012-14 Passats, which were sedan only in the NMS generation. They’re more reliable than the gen 2s, get better fuel economy and don’t have all the crazy extra complexity of the gen 3 engines from 2015.

AMGtech - now with more recalls! > dieseldub 09/19/2019 at 15:40

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Our first test for suspected bad DPF’s: lightly w the inside of the exhaust tip with a rag, if there’s black soot, the DPF is bad. So neat and easy.

RutRut > dieseldub 09/19/2019 at 15:52

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There is a way to make these super reliable but it’s not cheap. I worked on it for about two years with a previous employer. We created a system that instead of using delta pressure across the filter uses RF resonance inside the cavity to detail how much ash and soot are contained along with the spatial distribution. This helps avoid the dreaded soot ring and runaway thermal events. More info here: https://www.ctscorp.com/products/sensors-2/rf-dpf-sensor/

It shows huge gains in fuel economy and reliability, along with quite a few advantages for engine output feedback and state of filter.

Rusty Vandura - www.tinyurl.com/keepoppo > dieseldub 09/19/2019 at 15:59

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Tree hugger.

Rusty Vandura - www.tinyurl.com/keepoppo > dieseldub 09/19/2019 at 16:01

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I was a fan of diesel for many years and I enjoyed driving my ‘84 Jetta turbodiesel, until some knucklehead hit it and ruined it...

Mileage is great, but at the cost of emissions, or at the cost of adding horse pee-pee to the Blue Tank. Not hatin’ on diesel, but I do hate rolling coal...

John k > dieseldub 09/19/2019 at 16:47

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I own a 13 DSG Tdi se with 113K. I don’t have a lifetime average but 30 plus city and upper 40's highway is my real world experence. The highway range of 750 is more then i can do in a day. My best was 57mpg. In the rain going no faster then 45mph for a 157 miles. I would say that the trip computer is off by 10 percent and this guys mpg is likely if you drive highways at 70 or under. Repairs and maintenance run 2K+ per year and that is very difficult for me being disabled and on a fixed income. Not the cars fault. Vw’s are expensive to live with and i will never own one that uses gasoline. Ive had all the diesel stuff replaced under warranty execpt for the turbo. Rear brakes are original. So you take the good with the bad. The heat sucks and you can’t pass anything in a hurry unless your going over 2500 rpm in 6th gear in sport mode. But likes going 80. Since i can’t buy a GTD this will do

And my wheelchair fits nicely in the back seat.

If you put a chip in one of these which i havent upgrade the breaks to better then stock.

Just my 2 cents thanks for the article

John

North Carolina 

Future next gen S2000 owner > dieseldub 09/19/2019 at 17:02

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That’s a lot of annual miles.

VWBUSTUBE > dieseldub 09/19/2019 at 19:49

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Yeah, but the dieselgate "fix" makes them clog in less than 20,000 miles, especially if you do a lot of "stop and go" driving. As did mine three times with less than 80,000 miles.

subexpression > dieseldub 09/19/2019 at 21:00

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I’ve heard that gassers with particulate filters (OPF ) are showing up in Europe now. Design is based on DPFs .

DengrizKB1414 > dieseldub 09/20/2019 at 01:28

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Probably one of the most well written and thorough posts I’ve ever read on here. Phenomenal insight. I worked for a Deere (yellow) 6+ years back. The whole IT3 and IT4 engines were complained about SOOOO much... you’re right... there is a learning curve. There are growing pains. We’d be in horse and buggy otherwise. I’m not a diesel guy myself. Always been more akin to the Japanese. It’s too bad dieselgate set the tech back so horribly. Again... sounds cheesy but very well written piece. 

Buddybilt > dieseldub 09/20/2019 at 09:57

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Seriously...? It's just carbon. WE (as humans and LITERALLY ALL other life on this planet) are carbon based lifeforms. Chill out you morons. Buy a Tesla if you want to be "clean" but make sure your power to recharge comes from nuclear... Or you're just centralizing your emissions. Plus anyone buying a Jetta in the first place simply cannot afford a Tesla. So stop whining...

TahoeSTi > dieseldub 09/20/2019 at 09:59

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But without the DPF and a with a bigger turbo, these 2.0TDi’s really start to rip....and get another 5-10mph if you stay off the go pedal.

I had a 2009 which included all the growing pains a CR170 made them feel better. 

Buddybilt > dieseldub 09/20/2019 at 10:12

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Only a childish fool thinks “rolling coal” is cool. Christ I even hate the stupid phrase. Not only is it literally just dumping money out of your exhaust but it’s also not good for your engine. A diesel engine is going to “poof” a little black on acceleration and that’s both normal and fine. But the extent that most guys take it to is just retarded. AND! If i might add. NOT GOOD FOR DIESEL IMAGES PUBLICLY YOU MORONS! STOP IT!

That said... If you actually do the research. You’ll see that even old diesel engines from the 80s emit less of almost all regulated gases except NoX. (Nitrogen Oxide) which the last time I checked was breathed by a lot of plants and also makes up most of our atmosphere. Something like 75+% if I’m not mistaken. So just like cO2 regulations.. . Is a farce designed only to bring in money to the corrupt people that concocted this laughable scheme.

Now there are DEFINITELY emissions that could/can be harmful when one sucks on a tailpipe . Carbon Monoxide for example. But they’re not regulating the actually harmful emissions. They ALWAYS focus ONLY on the life giving gases and then vilify them as if none of us remember 6th grade botany class or 7th grade biology class.

You should all be ashamed for buying into this hook, line and sinker. I’m all for cleaner running engine of all types. Provided they meet 3 criteria. This is almost 2020 for Christ sake! So cars should be absolutely perfected by now. But because of EPA lies and slander campaigns. They’re only getting worse!

1. Reliable. Vehicles today should be so reliable that we only have to change fluids and normal wear items like brakes and belts.

2. Safety. I think we can all agree that most vehicles made today are safe. But that doesn’t mean we should just leave well enough alone.

3. Finally... POWER! if I can build an almost 100hp engine for a go-kart out of an old Kohler v-twin that started life at 24hp on the cheap and make it reliable then there’s no reason my wife’s “fun to drive” Jetta should have a problem getting to highway speed in a reasonable amount of time. Yeah VW 0-60 in 8.5 seconds... Turns out. DEFINITELY NOT "fun to drive"

dieseldub > dieseldub 09/20/2019 at 11:32

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For whatever reason, Kinja is not letting me respond to most of the replies at the moment. Seems to be a glitch.

There is a pending post from buddybilt I’d like to address.

“That said... If you actually do the research. You’ll see that even old diesel engines from the 80s emit less of almost all regulated gases except NoX. (Nitrogen Oxide) which the last time I checked was breathed by a lot of plants and also makes up most of our atmosphere. Something like 75+% if I’m not mistaken.”

Well aware. I’ve been one beating that same drum with regards to almost all regulated gases aside from NOx being naturally much lower than on gas engines, always have been.

I don’t believe I’ve heard of plants aspirating NOx, though. Usually that’s CO2 they’re breathing. And what makes up most of our atmosphere is plain N itrogen, not OXIDES of Nitrogen. Plain nitrogen, not bad. Even NO, not bad (hell, your body produces NO to keep your veins clear). But NO2, NO3 etc., not so great to breath. But, still better than carbon monoxide.

I otherwise don’t disagree with premises of power, reliability and safety as being better priorities than regulating nitrogen oxides down to near zero. Of course, that’s not what my post was about. I was merely admiring the effectiveness of particulate filters.

Sure, in most of the U.S. where diesel use isn’t very heavy, large particulates aren’t a real issue. But Europe has had worse air quality days in recent decades thanks to their governments collectively encouraging the mass adoption of diesels long before things like DPFs and SCR systems were devised.

If given the choice, if the emissions controls equipment on modern diesels were to remain as effective as they are now AND become genuinely reliable, would you honestly argue that you’re better off without those devices? If these devices were reliable, I personally would never bother removing them from any of my cars. Of course, all my diesels are all so old they were not equipped with DPFs in the first place. When these first came out in 2009 I told myself I’d allow at least a decade to wait and see how well these systems do in the long term. And some do fail with surprisingly low miles, unfortunately.

The owner of this particular car first spoke with me in 2015 after having his car about a year (2013 model he purchased used). This was also about a month or so after dieselgate went public. He found I seemed to be someone who knew what I was talking about when it came to these cars and emissions regulations in general— I was waiting for my shop permits to come through and had a lot of free time, so I actually went and read what the regulations were pre-2007 and what changed for the newer cars, I also spent time reading EPA and CARB studies on NOx and other pollutants.

The type of driving he does, very long distance freeway commutes to various job sites, is perfect for a modern diesel. I advised him that the best thing to ensure DPF longevity is to monitor exhaust gas temperatures, since the VW didn’t come with a light to tell you when a regen cycle is currently ongoing. They have a DPF light that is used if there’s a fault with the DPF or it simply hasn’t been able to complete a regen cycle in so long due to short trips that it’s now critical to continue to drive it until that light turns back off, thus indicating the regen has successfully completed, but when it goes through a normal routine regen, you’re not aware.

I told him a Scan Gauge II will be the easiest form factor to accomplish this and have a display full time of what the factory Exhaust Gas Temperature (EGT) sensors are reading (there are 4, one in the exhaust manifold pre turbo, one before the DOC cat and DPF, one after the DOC but before the DPF and one after the DPF). Primarily monitor one of the pre-DPF sensors and the pre-turbo sensor. Under normal conditions the temperature can range anywhere from 380 F to 1000 F, though that 1000 F is usually short lived, you have to sustain relatively hard acceleration to keep it there, the moment you lift it drops pretty quick. When the computer requests a regen, you could be sitting at idle making 1100 F EGTs where it normally would be closer to 400 F or so. And even under higher loads, it stays pretty consistent near 1100 F. I explain this to him and advise him for the longevity of the turbo and DPF, the best practice is to keep driving or at least let it idle until the cycle completes and the EGTs return to normal.

He took my advice to heart and here we are at 290,000 miles, and his DPF is still functional. Being in California where it’s not so easy to delete emissions devices due to regular smog checks, he’s not deleting anything. His turbo failed, trailered it to me to repair it and requested the DPF be replaced too, since it has to be removed during turbo replacement. I told him there were places that could clean it out and then we could reuse his old one since it’s not cracked, but he declined and decided he would rather put a new one in... 2 months later of waiting for a special order part from Germany, and here we are.

For what it’s worth, the way these work, they capture the soot particles and keep them in the filter. Eventually those particles create significant back pressure that will eventually impede engine performance. The backpressure of the filter is monitored by a differential pressure sensor to help calculate how much captured soot there is. Once it gets above a certain amount captured, it will trigger a regen cycle. Regen cycle is merely heating the exhaust for about 15 minutes and doing so burns the particulates and converts them to ash. The ash does stay in the filter, though. Gases much more easily pass through ash than the big carbon particles, but eventually the ash loading can get to a critical point where removing the DPF to clean it or replacing it are necessary to prevent overly frequent regens and the subsequent drop in fuel economy and reliability of other components. So, yeah, at 290,000 miles with the turbo needing to be replaced, it’s not a bad call to just put a new DPF on it while you’re in there. They’re not cheap, though.

The owner of this car is rather libertarian in his political views, but also abides by the law of the state he lives in and since he’s pretty mechanically inclined himself and is willing to keep track of every detail on his car, he’s definitely the ideal owner for one of these. At the end of the day, it’s a commuter that makes him money thanks to its efficiency and how much his work pays mileage. If he were in another state, I’m sure he would have considered removing the emissions equipment.

All that is besides my point. My main point was IF these were genuinely long lived and reliable for the average driver, would we have such an epidemic of people removing them? The other point of my post was to simply admire just how effective DPFs are at capturing particulates, even over 290,000 miles of driving.