Maybe EGRs wouldn't clog if......

Maybe EGRs wouldn't clog if they would just take exhaust from AFTER the particulate filter, basically you'd just have the inert gas needed to cool the cylinders to reduce NOx.....thoughts?

I could be wrong but it might not be "hot" enough after the dpf also maybe being dirty cleans more of the unburnt stuff before it get to the filters?

red golf tdi said:

Maybe EGRs wouldn't clog if they would just take exhaust from AFTER the particulate filter, basically you'd just have the inert gas needed to cool the cylinders to reduce NOx.....thoughts?

Click to expand...

You just described the low pressure EGR system found on every 2009+ CR 4cyl TDI sold here. Every NOx cheating, super efficient, fun, clean, quiet, 2009+ 4cyl TDI sold here.



And as we now know, even that isn't enough to bring the NOx limits into compliance, and that SCR is really the only way, and that would be used in addition to some sort of EGR, be it high or low pressure, or (as in the case of the CR TDIs), both.

Because clearly dual EGR alone, without SCR, is not enough.

Some engine manufacturers are ditching EGR altogether and just relying on optimizing combustion and SCR alone.

VW, take note of Scania's scr only engine...

Well since we don't have any other passenger car diesels here, and it is looking more and more like NO passenger car diesels AT ALL, I'd say something has to change if they want to meet these crazy NOx limits.

Because what works for trucks, for now, may not work for passenger cars. The principle is the same of course, but the limits are not.

Expect NOx limits to always be adjusted so gasoline cars can just barely meet the requirements, while diesel cars are just not quite able to.

That discrepancy between gas engines and diesel engines is what the EPA can always use to limit the proliferation of diesel passenger cars.

Mike_04GolfTDI said:

Expect NOx limits to always be adjusted so gasoline cars can just barely meet the requirements, while diesel cars are just not quite able to.

That discrepancy between gas engines and diesel engines is what the EPA can always use to limit the proliferation of diesel passenger cars.

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Just because you are paranoid, it does not mean they are out to get you.

https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100O9ZJ.pdf

please show me where diesels have lower nox limits.

https://www.epa.gov/emission-standards-reference-guide has more info.

Well it isn't a case of lower NOx limits, more a case of the current set of limits for EVERYTHING clearly favor gasoline fueled engines, particularly in passenger cars.

It would be different if they said "Let's allow for higher NOx on the diesels, in light of the fact that they EASILY will fall WAY below gasoline engines in everything else AND will achieve higher MPGs while doing so".

And the facts (using the collected WVU test data as my definitions of "facts" for this discussion) show that to be the case. When the NOx was high, the HC, CO, PM, etc. was way, WAY low. Like, down into the single percentiles. Lower than any gasoline engine (and I mean ANY of them short of hybrids during ICE-off periods, which is not all that often once underway) can get.

Diesels can run MUCH leaner than gasoline engines. Gasoline engine will start lean misfiring at ratios around 20:1, diesels can cruise down the road much leaner than that. They can idle at ratios leaner than 100:1.

But nobody is placing a 50 MPG target on all compact cars. Diesel powered ones can tag that with ease. Even modern ones, just that we don't get those available here because the powers that be assume we all want high HP. A 100hp CR 4 cyl in the 1.5L range moving a ~3000 lb car will have performance like a BEW car had but instead of topping out around 45 MPG average will hit 60.

But we cannot have that. We CAN have a 400hp 15 MPG GMC Sierra, though. You can buy those all you want.

meerschm said:

Just because you are paranoid, it does not mean they are out to get you.

https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100O9ZJ.pdf

please show me where diesels have lower nox limits.

https://www.epa.gov/emission-standards-reference-guide has more info.

Click to expand...

I didn't say the limit is lower for diesels.

The limit, which I assume is the same for gas or diesel cars, can be set at a point where it will be possible for gas cars to comply, but cost prohibitive for diesel cars to comply.

The limit is the same, but diesels have a harder time meeting the limit, in other words.

If the limit was established at a level that could readily be achieved in a modern diesel passenger car, then a gasoline car would comply with this limit even more easily.

I think NOx limits are being used to limit the proliferation of diesel passenger cars. Eventually, the limits may be reduced even more to favor electric vehicles over gasoline vehicles in the same way that they are currently favoring gas over diesel.

You both make good points.

https://www3.epa.gov/otaq/tier3.htm

for what it may be worth in this conversation.

To the OP, the reason the EGR typically comes from before the DPF is because it needs to be under enough pressure to overcome the boost pressure and be easy to meter. It is much easier to precisely control the input of a high pressure gas than one that is at almost the same pressure, or at a rapidly fluctuating pressure, compared to the inlet manifold pressure.

The non-SCR CRs had both high (pre-DPF) and low (post-DPF) EGR systems. To get the low pressure system to work they had to throttle the exhaust after the EGR valve, so it would be possible to force the gasses into the intake. Generally, exhaust restrictions are bad, so having that exhaust valve closed all the time is sure to negatively impact power and economy.

Other than that? Yes, a clean supply of exhaust to the EGR would be nice.

oilhammer said:

Well it isn't a case of lower NOx limits, more a case of the current set of limits for EVERYTHING clearly favor gasoline fueled engines, particularly in passenger cars.
It would be different if they said "Let's allow for higher NOx on the diesels, in light of the fact that they EASILY will fall WAY below gasoline engines in everything else AND will achieve higher MPGs while doing so".
And the facts (using the collected WVU test data as my definitions of "facts" for this discussion) show that to be the case. When the NOx was high, the HC, CO, PM, etc. was way, WAY low. Like, down into the single percentiles. Lower than any gasoline engine (and I mean ANY of them short of hybrids during ICE-off periods, which is not all that often once underway) can get.
Diesels can run MUCH leaner than gasoline engines. Gasoline engine will start lean misfiring at ratios around 20:1, diesels can cruise down the road much leaner than that. They can idle at ratios leaner than 100:1.
But nobody is placing a 50 MPG target on all compact cars. Diesel powered ones can tag that with ease. Even modern ones, just that we don't get those available here because the powers that be assume we all want high HP. A 100hp CR 4 cyl in the 1.5L range moving a ~3000 lb car will have performance like a BEW car had but instead of topping out around 45 MPG average will hit 60.
But we cannot have that. We CAN have a 400hp 15 MPG GMC Sierra, though. You can buy those all you want.

Click to expand...

This. Holy crap. Every single word. Could not have put it better.

oilhammer said:

Well it isn't a case of lower NOx limits, more a case of the current set of limits for EVERYTHING clearly favor gasoline fueled engines, particularly in passenger cars.
It would be different if they said "Let's allow for higher NOx on the diesels, in light of the fact that they EASILY will fall WAY below gasoline engines in everything else AND will achieve higher MPGs while doing so".
And the facts (using the collected WVU test data as my definitions of "facts" for this discussion) show that to be the case. When the NOx was high, the HC, CO, PM, etc. was way, WAY low. Like, down into the single percentiles. Lower than any gasoline engine (and I mean ANY of them short of hybrids during ICE-off periods, which is not all that often once underway) can get.
Diesels can run MUCH leaner than gasoline engines. Gasoline engine will start lean misfiring at ratios around 20:1, diesels can cruise down the road much leaner than that. They can idle at ratios leaner than 100:1.
But nobody is placing a 50 MPG target on all compact cars. Diesel powered ones can tag that with ease. Even modern ones, just that we don't get those available here because the powers that be assume we all want high HP. A 100hp CR 4 cyl in the 1.5L range moving a ~3000 lb car will have performance like a BEW car had but instead of topping out around 45 MPG average will hit 60.
But we cannot have that. We CAN have a 400hp 15 MPG GMC Sierra, though. You can buy those all you want.

Click to expand...

Excellent point oilhammer. GMC anyone?

Excellent point about 400hp GMC getting 15mpg is just fine.

What burns me up is VW knew the system was inadequate for the DPF to live and I paid to have one fixed.
This is a direct result of their fraud and deceit.
They should make the victims of THIS whole as well.
All of the clogging DGR filters are a direct result of an under designed system.
The later two piece was just to keep their warranty costs lower and that still did not fix the problem.

Since my wife is concerned that the resale value will plummet she wants to turn these in and we are looking at a van and I wonder if Oilhammer has any experience with 2014 - 16 and the new 2017 Chrysler minivans?
What problems do you see compared with the Honda Odyssey and Toyota Sienna?
I am looking for one with the towing package factory installed.
We got 280,000 miles out of our last Plymouth Caravan (1998 with some work of course)

Boy if I had to choose a new(ish) minivan I am not really sure what I would choose. But I would give the Metris a look, that is for sure.

Toyota: I think they finally got their GR family of V6 engines mostly ironed out. And their Aisin transmissions seem fine, just the possibility of a valve body failure at some point although I think that may be able to be avoided by frequent ATF changes.

Honda: their V6s are great, but their VCM version which I think is now standard equipment is a bit goofy and they still have not figured out how to make the engine mounts more durable and they are jaw dropping expensive to replace. Their transmissions are still a crap shoot, but avoiding moving them from D to R while still in motion and ALWAYS setting the parking brake properly is and has always been a hallmark to avoid Honda slushbox problems.

In either case, those are American vehicles, and as such do not exhibit the eye-surgeon level of quality that Japanese versions do. The body panel fit, especially over time, is not as good as many of their other models, and the interior NVH over time gets a little tiresome. My sister's 2006 Sienna (I know it is still the second gen) is abysmal to drive because of this. Downright awful. My half million mile 2000 Volkswagen feels tighter than he Sienna at 200k, and they are all like that. Our shop has one too.

The Chrysler I think still holds its own in the ergonomics department, and despite being chock full of parts wearing the ubiquitous "Made in China" tag on them, they hold up reasonably well. Better than I would have thought they would to be honest. The early Pentastar V6 (which has replaced ALL of the 6cyl engines in the ChryCo lineup) had a lot of problems. They have worked to remedy that and the latest ones seem pretty good. And they have a boatload of power, even in the detuned version the minivans get. But the 6sp automatic they use seems to be hit and miss. Early ones were mostly miss. It is just a modified version of the old crap-o-rific 4sp slushbox they came up with in the late '80s. They just added an extra planetary gearset (thus making it and the existing ones thinner). And that was a pretty bad transmission. They had many, MANY updates for them, and just about the time they got them reasonably ironed out, they did away with them. Oh, the also placed a cover over that noisy assed solenoid pack that you always hear on the 4sp units buzzing away as you come to a stop.

Fiat did a miracle job redoing the interior on all the vehicles they inherited from the DaimlerChrysler failed marriage, and the minivan is no exception. Its dashboard is MUCH nicer, as are all the interior fitments, trim panels, seats, etc.

Since this will be the last hoorah for the ChryCo minivan, you may be able to get one of the later ones pretty cheap. They will only now have the Chrysler Pacifica, which is a totally different platform sharing a lot of its underpinnings with the current Cherokee, 200, and Dart. Tough to say how it will be, but they've already had lots of problems with the 9sp ZF slushbox, much of it remedied with software, but those updates seem to only fix some of them some of the time.

Seriously, I would go take a Metris for a spin. You'd be surprised how nice they drive.

Thanks for the information.
I always appreciate any little thing you might contribute.
Big things too.

I'm a newb here, just joined last night..
I farm and run several power units to pump water for irrigation. Some diesel, some propane *spec built just to run soley on propane.
Guess what? even though propane is already one of the cleanest burning fuel, epa still thinks it can be better. and mandates full compliance on all new installs.
Last engine I bought is a 8.1 L gm based unit. obdII , catalytic converters.. just to squirt water on a crop that is removing mega tons of CO per year..
LOL, anyone ever smell burnt propane that goes through a converter? It's nothing like what a BBQ grill smells like.
It's the most acrid ammonia stink.. it'll peel your eyeballs.
Epa.. Everyone's Pain in Ass..

Hah! That is the same deal as a few years back when I rebuilt 22 Volkswagen Industrial engines.... the old air cooled ones. Most were the 1600cc type, but a few were 1200cc units. From the '60s. They were all still in excellent serviceable shape. The company just wanted them all "refreshed" over the winter, and they were in the same boat: couldn't install new ones because of a bunch of red tape.

So, we rebuilt all 22 1960s/early 1970s tech engines, that are still in use today. They do not run all the time, just when needed in certain fields. But they still do exactly what they were designed to do.

Biggest problem they have is mice getting in them and building nests in the cooling ducts. The same company blew up a Deutz air cooled diesel a few years ago due to that.

The diesel in Rang Rover uses the exhaust gas after the dpf in the egr

Are we intentionally avoiding two big issues? All the talk about soot, that then devolved into discussions of a few 'small potatos' emissions, ignores that biodiesel has much less soot formation and is nearly fossil CO2 neutral.
Intake manifold clogging due to soot has been reversed (not just been kept at bay) by high percentage biodiesel use.
NOx is measured in what? grams per gallon? milligrams per mile? CO2 production from fuel combustion is measured in kilograms per gallon. Atmospheric CO2 absorption, today (not in the carboniferous epoch), by the crops grown for next season's food and then fuel, nearly offset every bit of the CO2 that will be released by the harvest, processing, and eventual combusion of biodiesel.

Now, if only I could run year-round on b100 biodiesel, and could be prohibited from using petroleum diesel at all, I expect that I'd not need all the emissions controls that petroleum diesel requires.

Lug_Nut said:

Are we intentionally avoiding two big issues? All the talk about soot, that then devolved into discussions of a few 'small potatos' emissions, ignores that biodiesel has much less soot formation and is nearly fossil CO2 neutral.
Intake manifold clogging due to soot has been reversed (not just been kept at bay) by high percentage biodiesel use.
NOx is measured in what? grams per gallon? milligrams per mile? CO2 production from fuel combustion is measured in kilograms per gallon. Atmospheric CO2 absorption, today (not in the carboniferous epoch), by the crops grown for next season's food and then fuel, nearly offset every bit of the CO2 that will be released by the harvest, processing, and eventual combusion of biodiesel.

Now, if only I could run year-round on b100 biodiesel, and could be prohibited from using petroleum diesel at all, I expect that I'd not need all the emissions controls that petroleum diesel requires.

Click to expand...

CARB has issue with biodiesel from transesterification. Apparently their tests show that the fuel generates more NOx. They have actually forced retailers in California to stop selling 100% concentrations of the stuff due to that. I wouldn't be surprised if the EPA starts to clamp down on it outside of California at some point.

The places here that want to sell 100% bio-sourced fuel now have to blend their transesterified biodiesel with a different kind of bio-based diesel fuel, namely something NexBTL-based from Neste oil at the moment (Propel sells it under their HPR name, a couple other local retailers have started selling it with their own branding as well, but vast majority of it is sourced from the same Asian plant owned by Finland's Neste oil).

The NexBTL actually does significantly lower soot creation as well as all other forms of regulated emissions, NOx included. And chemically is much more similar to petro diesel than transesterified biodiesel. This translates into far fewer fuel system clogging issues, at least here in California where all our retail biodiesel has been transesterified WVO rather than from a virgin oil source. That stuff does nasty things to fuel system internals...

The one downside is the complete lack of aromatics in the NexBTL based stuff will make VE rotary pumps leak if they already have old, questionable seals on the verge of leaking. The NexBTL will absolutely push them over the edge and make the pump into a gusher. A new set of seals will of course fix that and you won't have an issue in the future.

Funny I never seemed to see much of an issue with the virgin soybean-oil based stuff in the Mid-West. But the WVO-based stuff here in California is pretty horrifying.

There are lots of benefits to drawing the EGR post-catalyst and readmitting it upstream of the turbocharger compressor, but as Brian noted, it requires a positive pressure differential - which is usually achieved though an exhaust throttle flap or an intake throttle to create a partial vacuum, neither of which are desirable from the standpoint of pumping losses. However, as we move ahead in technology, I believe this will become the most widely used route, not only because it keeps the plumbing clean but also because cooled (LP)-EGR has emissions benefits over uncooled.

I would like to see studies and implementation of DEF being fumigated into the intake side rather than in the exhaust; it's a much better environment in the engine compartment where components are relatively more protected from ambient freezing temperatures and road salt in wintry locales and from impact damage from road debris errant material.

oilhammer said:

Well it isn't a case of lower NOx limits, more a case of the current set of limits for EVERYTHING clearly favor gasoline fueled engines, particularly in passenger cars.
It would be different if they said "Let's allow for higher NOx on the diesels, in light of the fact that they EASILY will fall WAY below gasoline engines in everything else AND will achieve higher MPGs while doing so".
And the facts (using the collected WVU test data as my definitions of "facts" for this discussion) show that to be the case. When the NOx was high, the HC, CO, PM, etc. was way, WAY low. Like, down into the single percentiles. Lower than any gasoline engine (and I mean ANY of them short of hybrids during ICE-off periods, which is not all that often once underway) can get.
Diesels can run MUCH leaner than gasoline engines. Gasoline engine will start lean misfiring at ratios around 20:1, diesels can cruise down the road much leaner than that. They can idle at ratios leaner than 100:1.
But nobody is placing a 50 MPG target on all compact cars. Diesel powered ones can tag that with ease. Even modern ones, just that we don't get those available here because the powers that be assume we all want high HP. A 100hp CR 4 cyl in the 1.5L range moving a ~3000 lb car will have performance like a BEW car had but instead of topping out around 45 MPG average will hit 60.
But we cannot have that. We CAN have a 400hp 15 MPG GMC Sierra, though. You can buy those all you want.

Click to expand...

I agree 100% on emissions, and would go a bit farther too. Diesels have the lowest levels of particulate emissions by a long shot. I think we should bring the emissions limits for all cars down to those levels using real world tests. If gassers now need particulate filters, so be it. Cleaner air for everyone, and the cost of particulate filters will also drop, which helps the added costs of diesels. We should do the same for CO, HC, and NOx emissions as well. Whichever cars have the lowest emissions in each individual category should set the limit for all cars, so manufacturers have to reduce emissions across the board.

I'm not sure if 60mpg real world is doable in a 3klb VW though, even with a 1.4l TDI. That's what the current gen Jetta is at and it only hits ~60mpg at a steady 50mph cruise.

https://avt.inl.gov/sites/default/files/pdf/ice/fact2013volkswagenjettatdi.pdf

Don't get me wrong, it's way better than someone commuting solo in a giant pickup. But the TDI is still behind VW's hybrid Jetta because partial load still hurts efficiency with a diesel, although a diesel hybrid wouldn't have that problem.

https://avt.inl.gov/sites/default/files/pdf/hev/fact2013volkswagenjettahybrid.pdf

And the hybrid Jetta is a way's behind cars that are built from the ground up as hybrids (aerodynamic design, electric accessories), *especially when they have a larger battery pack.

https://avt.inl.gov/sites/default/files/pdf/phev/fact2013toyotapriusphev.pdf

*A bigger pack lets the car light off the emissions system as efficiently as possible, and once the car's warmed up, it can recharge the battery when the engine is most efficient.

60 MPG is easy in a 3000 pound car. People already do it. You just have to have the right technology.

If I drove a steady 60 MPH in my Golf, I'd hit 60 MPG easily. And that is in a car that is 16 years old, with an engine that has technology dating back 25 years, based on technology dating back 40 years.

The problem comes in when we cannot be allowed to equate fuel consumption with emissions due to NOx, and pushing everything else aside. Which is exactly what we have done.

BUT... I still say you can have the best of both worlds if it was just made available. The ALH makes 90hp, and moves down the road just fine. The VAST majority of everyone who bought and owns those cars feels this way. I still service boatloads of those cars, 95% of which are completely "stock" as they left the factory. I do not hear of any complaints about the 90 horses being unable to move the car.

Well, currently, Volkswagen HAS (as in, they are already building them, and have been for some time) TDI engines that make at least as much power in some cases slightly more but with less displacement, better engine management, and more stringent emissions controls, that use less fuel. This is not a pie in the sky dream, they already exist. We just cannot buy any here.

People here have bought Prius models in decent numbers, and those cars are WRETCHEDLY slow. I've driven and serviced just about every single Prius model ever sold here. We have one as a shop car, I've driven it quite a bit over the years. I know how abysmal they are to drive. But they buy them. And they are a great car for the people that make that their choice of transportation.

oilhammer said:

People here have bought Prius models in decent numbers, and those cars are WRETCHEDLY slow. I've driven and serviced just about every single Prius model ever sold here. We have one as a shop car, I've driven it quite a bit over the years. I know how abysmal they are to drive. But they buy them. And they are a great car for the people that make that their choice of transportation.

Click to expand...

So, funny thing, with how people feel a car is fast.

People have real trouble feeling velocity - there's some cues we can use (sound, vibration, that kind of thing), but it's very hard.

People can kinda feel acceleration (change in velocity), but not really. Again, sound is a cue here, as is the force pushing you back in the seat.

What people really feel is jerk, or change in acceleration.

Every generation Prius after the first generation actually accelerates faster than the ALH - 11.3 seconds to 60, and 18.3 seconds @ 75 MPH in the 1/4 mile for the ALH per MotorWeek (using a 2001 Jetta GLS manual), 10.2 seconds to 60, and 17.7 seconds @ 79 MPH in the 1/4 mile for the Gen 2 Prius, and I know the later generations got faster due to adding more power. (They used estimated or manufacturer figures for the c and v, and they didn't give figures for the Gen 3 or 4, or I'd have quoted those. As far as the Gen 1, they got 12.2 seconds to 60, and 18.9 seconds @ 75 MPH for the 1/4 mile.

However, the ALH gives a big lump of acceleration in first, then you shift. It gives another big lump of acceleration in second, and another in third. This means that you get 3 hard jerk events, and in the 1/4 mile, you're getting 4 jerk events. In addition, the engine note is changing through each gear.

Conversely, in the Prius, you pin the throttle, it goes to redline, and that's it - you get one jerk event off the line, and then you're getting smooth acceleration, and little change in engine note (it does rise, but not much). That feels less sporty, even though it's actually faster.

I must be more skilled at driving a diesel than any clown at Motorweek then.

I can see getting 60mpg@60mph in an ALH Jetta. Fueleconomy.gov puts it at 44mpg highway while the 2013 DSG only hits 40mpg highway. I'm guessing most cars could do better if manufacturers were able to loosen up emissions standards to whatever they were when the ALH was being built. I can't say I'm a huge fan of my latest gen-ii Prius for driving, but the prices have come down so much (I paid $1500) that I don't care much either. Then again, if I could find an ALH with some easy to fix problems for $1,500 I'd be tempted to grab one as a long distance driver/back-up sedan.