VW-Style Cheating: An Experiment

[OVERKILL]

Originally Posted By: jrmason
Your turning the discussion into something it isn't.


That certainly isn't my intention, I was just pointing out the logical fallacy of EGR on a diesel which appears to be more of a hindrance than a benefit

Originally Posted By: jrmason
i I never stated the positives outweigh the negatives in EGR.


Don't worry my intention was not to imply that you did

Originally Posted By: jrmason
I've cleaned enough intakes and turbos (and rebuilt a few) to know how detrimental it is to the guts of an engine.


I can certainly believe that. My buddy who owned the 6.0L PSD I mentioned (which of course was an '05 so it didn't have a DPF or regens, just EGR and a diesel cat of sorts) is an HD diesel mechanic at our biggest local truck shop. Works on everything from the little guys to the big ones. I've seen all kinds of stuff that he's either sent me via text or that he's had me take a peek at while he was wrenching on it. I couldn't believe the difference the EGR delete made on his PSD. Now of course being only EGR, since there are no regens, the fuel economy difference was solely EGR related.

Originally Posted By: jrmason
The fact is your still sending more emissions out the tail pipe for the DPF to process, which leads to more active regens which leads to more fuel being burned on the exhaust stroke to clear the DPF. At best it might be a wash, but certainly no 30-40% increase in mileage.


Would be neat to see the numbers on this. I say that because we know EGR, on a non-DPF equipped diesel, causes an increase in fuel consumption (as illustrated by the MPG hit) so it is obviously, based on this fact alone, generating more particulate. That particulate is not all ending up in the oil or as coking, some of it is going out the tail pipe and into the DPF.

A diesel is going to generate soot regardless. Making it choke down its own fecal matter and wash it down with some extra fuel (EGR) doesn't seem like it would aide in the reduction of soot, whose production is likely pretty consistent relative to the amount of fuel burned. Of course we do know that it works to reduce NOX, but in terms of a solid that is generated that isn't converted into something else via additional exposure to the combustion process and is liable only to end up lining parts of the engine or surfing around in the oil (which is an emission in and of itself

) I dunno

Great discussion so far BTW

 

[KrisZ]

Originally Posted By: jrmason
The fact is your still sending more emissions out the tail pipe for the DPF to process, which leads to more active regens which leads to more fuel being burned on the exhaust stroke to clear the DPF.


I'm not sure it is a fact. In fact it took me just a few seconds to find materials that totally disagree with your "facts".
Soot in oil can only get in one way, which is the same as the DPF and it is through the cylinders. So if the oil is loaded with more soot, that goes through cylinders, then that extra soot also has to go to the DPF.

http://www.cambustion.com/products/egr
"Since EGR reduces the available oxygen in the cylinder, the production of particulates (fuel which has only partially combusted) is increased when EGR is applied. This has traditionally been a problem with diesel engines, where the trade-off between NOx and particulates is a familiar one to calibrators."

http://www.sciencedirect.com/science/article/pii/S1110016812000907

"Reductions in NOx and exhaust gas temperature were observed but emissions of particulate matter (PM), HC, and CO were found to have increased with usage of EGR. "


Edit:
And the difference between EGR and no EGR can be quite significant. Some engines can run up to 50% EGR! That is huge!

 

[mobilaltima]

will you be deleting the new truck?

 

[A_Harman]

Can't wait to hear the discussions when GPF's hit the market...

 

[DoubleWasp]

Originally Posted By: jrmason
Your turning the discussion into something it isn't. I never stated the positives outweigh the negatives in EGR. I've cleaned enough intakes and turbos (and rebuilt a few) to know how detrimental it is to the guts of an engine. The fact is your still sending more emissions out the tail pipe for the DPF to process, which leads to more active regens which leads to more fuel being burned on the exhaust stroke to clear the DPF. At best it might be a wash, but certainly no 30-40% increase in mileage.


I'm afraid you are completely alone in this conclusion.

 

[DoubleWasp]

Originally Posted By: mobilaltima
will you be deleting the new truck?


Probably. It'll be no different that if it were a 2007 with the 5.9, instead of the 6.7.World will continue to turn.

 

[Olas]

Yet another reason to buy something that predates the emission rules, keep it maintained and free yourself from all these worries.

 

[artificialist]

I suspect other cars have been making fake smog numbers for years. I would sometimes encounter an older Toyota Sienna van with a P0420 code. The actual fix was not to replace upstream and downstream oxygen sensors and cats, the fix was to reflash the computer.

That sounds very suspicious to me.

 

[supton]

Originally Posted By: Olas
Yet another reason to buy something that predates the emission rules, keep it maintained and free yourself from all these worries.


I think like that often. Then every so often I get stuck behind something that lacks a catalytic convertor, and then I wonder if I really want to be that guy. I know, some cars are worse than others; but I like riding my bicycle and being outside and whatnot--and boy, clean air is good air.