Managing a sooty tailpipe

Wilcharl,

I should have noted that the glow plug flashes, and rpm increases while the basic settings are being run.

great you got it to work. also of note is that in basic settings, before you press the ON/OFF/Next button, the EGR(spec) and EGR (actual) values track together pretty closely.

so for your car, as of now, could you complete this info?

Tailpipe condition: [clean, little soot, massive soot]
Odometer miles:
Codes recorded: [P0401, other?]
MIL?: [yes, no]
Basic settings EGR:
EGR Spec OFF/99% duty cycle/EGR (actual): 520
EGR Spec ON/60% duty cycle/EGR (actual): 375
OFF - On: 155

This shows that the commanded and actual EGR values are tracking together.

wonder if they would diverge when the MIL P0401 is set.

of course, we have no idea where these EGR values come from. could just be valve position, or could be a calculated value for EGR based on a couple other inputs.

Tailpipe condition: Some soot ; wipe it about every 3 weeks and there is minimal on white paper towel

Odometer miles: 95554

Codes recorded: [P0401, other?] None currently
MIL?: [yes, no] No
Basic settings EGR:
EGR Spec OFF/99% duty cycle/EGR (actual): 520
EGR Spec ON/60% duty cycle/EGR (actual): 375
OFF - On: 145

I think I will check it again at 100,000

Hoping we can grab some data off a car with no soot and super low mileage

It also would be good to get the data from a car or two with the P0401 code.

meerschm said:

First open up the engine controller, then select basic settings

there is a pull down menu to use to pick the Exhaust Gas Recirculation(EGR)

when you do so, the following screen comes up.

note the text (prerequisites....). you can see my engine was idling. In this screen, the exhaust gas recirc(Spec) and exhaust gas recirc(actual) should track and be close to each other. My car was also warmed up to operating temperature after a drive.

I pressed the on/off/next button, then pressed brake and accelerator pedal (not sure you really need to press the brake and accelerator)

(the computer controls the rpm, but just wants to verify you are at the wheel, and ready for the test)

The glow plug indicator on the instrument panel flashes while this test is under way.


the next two screens show values with the EGR commanded off ,and then on. the ecu controls the back and forth, till you close the window or press on/off/next again.

Click to expand...

Thanks so much, Mike. This really helped!

P.h.Diesel said:

Thanks so much, Mike. This really helped!

Click to expand...

\
you are welcome, could you add some info on what you see?

Tailpipe condition: [clean, little soot, massive soot]
Odometer miles:
Codes recorded: [P0401, other?]
MIL?: [yes, no]
Basic settings EGR:
EGR Spec OFF/99% duty cycle/EGR (actual): [value in mg/str]
EGR Spec ON/60% duty cycle/EGR (actual): [value in mg/str]
OFF - On: [difference in mg/str]

I have the code coming on with my car. Sooty tail pipe at 60393 miles, took it to dealer they said they did a ECU update. I took the car home next morning P0401 code on way to get coffee. I have My VCDS just updated just letting my laptop charge then I'm gonna go check mine

60,000 should be covered under the emissions warranty would be awesome if we get some numbers from you before and then after VW pays to replace your DPF


Sent from my iPad using Tapatalk

couple more graphs

I figured out today you can log the data during the basic settings.

the figures do bounce around a bit, these are from my cold engine I started just to run basic settings this morning.



above is a plot of the EGR actual in blue, while the % changes between just at 60 and 100%




this second one is a scatter plot, with the % commanded on the vertical, and the mg/str of EGR on the horizontal.

this shows the amount of scatter I saw.

these cold values run a higher EGR than my previous ones from a warmed up engine, but the difference still is around 120-140 or so

If I average the readings, (within a stable % requested) I get 422 and 565 mg/str or a difference of 143

Ran the egr basic settings after ten mile drive to work on a warm engine,

logged and averaged values for the on/off cycle (tossing a couple readings after the transition between %egr changes)

saw 405 and 545 for a difference of 140 mg/str of egr

I jus did mine I was 340 to 547 I took video and pictures but I don't know how to post them. I can email them to someone if they wanna post it for me.

I will send you an e-mail

wow. so you still have the P0401 code and MIL lit?

looks like you got a difference of over 200 for the EGR basic settings

The MIL light coming on every now and then, I haven't been driving much since I'm on vacation. I will also send you a photo of my tail pipes.

http://forums.tdiclub.com/showthread.php?t=286691

might help with the photo posting.

Today there is a lot of discussion with the EPA violation notice but there is an update which may be of interest here.

I followed up with hymato, and looked at some logged data he collected from running the EGR basic settings on his car.

averaging the data, I saw 366 and 538 mg/str for the basic settings, or a difference of 172 mg/str of egr

this is less than the 200 plus difference he picked out by eyball averaging, but well over what we thought was the 100 mg per str difference we thought was associated with the P0401 error.

looking back, hymoto had the software recall performed. perhaps one of the things the update did was change the threshold for throwing the error.

so for anyone reading this who has a sooty pipe, perhaps postponing the recall software update may be advised.

Mine had the software update almost immediately after the notice was issued so my delta of 145 and no light on is with the update


Sent from my iPhone using Tapatalk

Thanks.

guess we just keep watching and see if there is any reliable reading we can tie to the start of the P0401 error.

more data from more cars would help.

perhaps VW changed the software update along the way. there was another post in july from someone who did the update and saw the P0401 error within a week.

this level of detail is why the folks at the ross-tech forum start every question with an auto-scan of the whole car.

If you're talking about the 23O6 update, I believe that is to modify the CEL threshold for NOx, not for EGR flow.

The reflash that VW had for the P0401 is no-longer out there . They are making you buy a new DPR and EGR filter.

On the EGR limits if it drops too or below the 100 mg/str of egr spread is when it will flash a code for P0401 meaning the DPF is cracked or plugged.

VeeDubTDI said:

If you're talking about the 23O6 update, I believe that is to modify the CEL threshold for NOx, not for EGR flow.

Click to expand...

We think.......

we do not have a full list of what all is in the update, do we?

EGR control is part of the NOX reduction**, so it is not out of what I could imagine for VW to decide to tighten up the error code trigger value in an attempt to improve NOX readings. (total guess on my part, but trying to fit all the limited data available)

and at least two folks had a P0401 pop up shortly after the recall software update.

one of which has both the P0401, and an EGR basic settings difference of well over 100.



** see the 2.0-TDI-SSP.pdf page 25

With rising engine load and engine RPM, the​

recirculation of exhaust gases is shifted to the Low​

Pressure EGR system to increase the recirculation​

rate. This happens in order to obtain optimal​

NOx reduction at middle and high engine loads.​

Particularly in the high engine loads, the cooled Low​

Pressure EGR is a very large advantage over the High​

Pressure EGR system.
​

CNGVW said:

The reflash that VW had for the P0401 is no-longer out there . They are making you buy a new DPR and EGR filter.

On the EGR limits if it drops too or below the 100 mg/str of egr spread is when it will flash a code for P0401 meaning the DPF is cracked or plugged.

Click to expand...

Understood. ( I did not know there was any flash for the P0401)

but the EGR is needed to control NOX emissions. (which is why it throws the code when it is not capable of working within some value set)

the cracked DPF allows soot to get where it should not, filling the filter.

I like to see the data. I believe you that the 100 mg/str difference is the limit, which is in the basic settings notes, and It sounds like you have verified looking at cars.


but the data from hymoto presents a puzzle. he has the sooty pipe, P0401 errors, and intermittent MIL but an EGR basic settings difference of somewhere between 170 and 200 mg/str, which is well over the 100 mg/str difference. He also had the NOX emissions motivated ECU update.

Hence my conjecture that the software patch may have increased the difference value required for the basic settings test to not throw the P0401 value (or whichever similar monitor of engine controller data that actually throws the code)

do you have sets of Basic settings EGR values for cars which do not have the cracks in the DPF?

Just a heads up, guys. The basic setting 03 is HIGH pressure EGR. This won't tell you much of anything about how the EGR filter is doing. The EGR filter is for the low pressure EGR system. They are two completely separate EGRs that pick up exhaust gases at different parts in the exhaust stream and also get introduced back into the intake stream at completely different areas.

The high pressure EGR is conventional, same basic principle as it always has been on previous TDIs. It takes exhaust gas from the well-pressurized exhaust region before the turbo, this is what allows it to overcome the little bit of pressure in the intake system and be introduced into the intake stream under light loads.

Since NOx requirements have gotten so much stricter, the low pressure EGR was needed as it could potentially be used under all load conditions, not just light loads.

So, they take exhaust gases post-DPF, then it has to go through the EGR filter, and it gets re-introduced into the intake where there actually is a bit of vacuum: near the inlet of the turbo's compressor. Meaning the low pressure EGR has to go through the compressor housing of the turbo, all the intercooler ducting (wonder how intercooler icing became a thing? Thank low pressure EGR) before it finally gets into the intake manifold. The high pressure EGR goes from exhaust manifold straight to the intake manifold.

So, that having been said, there are two separate EGR systems to do testing on. Basic setting 03 is the same as it always has been, this cycles the high pressure EGR.

Basic setting 67 is what cycles the low pressure EGR. This is what will actually give you a good idea of if there's clogging with the EGR filter. Difference in value should be greater than 100.

Basic setting 68 will actuate the exhaust flap that's way downstream. Difference in pressure should be greater than 50 mbar.

Basic setting 78 also gives you an idea of how clogged the filter is. I don't believe this cycles any valves, but it does raise the RPM and creates a fair bit of exhaust pressure and allows you to view the differential pressure before vs. after the low pressure EGR filter in fields 1 and 3. The difference should be LESS than 100 mbar.

There's two exhaust differential pressure sensors, one keeps tabs on the pressure differential before vs. after the DPF. The other keeps tabs on pressure before vs. after the low pressure EGR filter. That's what basic setting 78 is letting you see, the differential pressure before vs. after the EGR filter.

2013-14 CJAA engines also have a basic setting 49 that is a pass/fail test for the DPF. 2012 and earlier do not have this.

And, of course, if you have a Passat CKRA or anything EA288 based, they use the UDS protocol. They don't use measured value and basic settings in numbers, they use a sometimes difficult to decipher wording for each function and measured value.

I don't have the exact wording here to direct those owners specifically, but some searching around in VCDS and we should be able to find it.

Thanks, Matt!

I was fishing for the right values to watch, just got carried away before confirmation.



Probably have to start over.

took a few readings, (values from logs collected and reviewed after the fact. used averaging function in excel to pull a value. the mg/str bounce around a bit)

and on my 2009 CBEA with a pretty sooty tailpipe, 151000 miles or so, with no reported ECU errors (and no P0401)

I see for Basic setting 67 (which is in the pull down menu)
Exhaust Gas Recirculation (EGR) Low Pressure Valve Function/Test Adaptation

after pressing the on/off/next

Off 99.4% 542 mg/str (averaged)

On 40.2% 364 mg/str (averaged)

for a difference of 178 mg/str



For Basic settings 78,

after pressing the on/off/next

field 1: 51 or 54

field 3: -3

which is a difference of 54-57 or so.

I can't believe the thread got this far before someone who knows what they're talking about replied (anyone who has read the VW tech write up on the 2.0 CBEA/CJAA, I have a copy).....thanks Matt for saving me the time!

well I came across this thread while doing some research, interested in Dr.CNG's EGR filter....

Matt-98AHU said:

gets re-introduced into the intake where there actually is a bit of vacuum: near the inlet of the turbo's compressor. Meaning the low pressure EGR has to go through the compressor housing of the turbo

Click to expand...

I wonder what it is made of and whether or not there is a risk of F.O.D.?

GTiTDi said:

I can't believe the thread got this far before someone who knows what they're talking about replied (anyone who has read the VW tech write up on the 2.0 CBEA/CJAA, I have a copy).....thanks Matt for saving me the time!

well I came across this thread while doing some research, interested in Dr.CNG's EGR filter....



I wonder what it is made of and whether or not there is a risk of F.O.D.?

Click to expand...

do you have a copy of this tech write up you could share?

I have read the self study program, but it sounds like you have a reference which is more relevant.

the first post does ask for help with the right measurements.

I had hoped he (Bob) would share more details of what he did to the filter at the fest, but he came with one sealed up, and a cracked DPF to show and tell.

When my code comes on (if VW doesn't offer some type of warranty extension or the whole exhaust system is reworked by them due to their little EPA problem) I will likely go with the Dr. Bob option but I am quite curious what is inside the sealed can... A different media? Less media? Just air? a hole in the legacy media?

meerschm said:

do you have a copy of this tech write up you could share?

I have read the self study program, but it sounds like you have a reference which is more relevant.

the first post does ask for help with the right measurements.

I had hoped he (Bob) would share more details of what he did to the filter at the fest, but he came with one sealed up, and a cracked DPF to show and tell.

Click to expand...

I am talking about the SSP. It doesn't seem like all of us "in the know" have actually read it...

wilcharl said:

When my code comes on (if VW doesn't offer some type of warranty extension or the whole exhaust system is reworked by them due to their little EPA problem) I will likely go with the Dr. Bob option but I am quite curious what is inside the sealed can... A different media? Less media? Just air? a hole in the legacy media?

Click to expand...

I can tell you what is in there originally...a fine stainless mesh with a fabric/gauze type covering...remember this exhaust air should be particle free provided the DPF is working..you don't want any debris to hit the turbo compressor wheel turning at 20K RPM+, so they put the filter in line with the exhaust pipe and LP EGR valve in the event of a cracked DPF soot particles dont damage the turbo.
I'll post up some pictures of the EGR filter I have cut open for inspection soon.

GTiTDi said:

I am talking about the SSP. It doesn't seem like all of us "in the know" have actually read it...


.

Click to expand...

was just unsure of which vcds measuring blocks and basic settings are for what sensor. sometimes it seems it is like tossing chicken bones and trying to figure out what time the moon rises.

Guess more time with the VCDS would yield results. mostly, I prefer to drive. sitting in the driveway with the engine running never seems like the best idea.

should have known that label for basic settings referencing the EGR without modification would be the HP one. kind of like the story of the fraudulent sword marked "World War I"



SO, where does the idea that the LP EGR difference flow trips the error at 100 mg/str come from? is it stated someplace, from experience, or just a rough guess?

I saw a note that the HP EGR basic settings difference should be over 100, but not such a note in the LP EGR basic settings screen.