Managing a sooty tailpipe

Couple more samples of freeze frame from P0401 error.

from http://forums.tdiclub.com/showpost.php?p=4757334&postcount=1

Load: 89.8 %
Load: 100.0 %
Mass Air / Rev.: 490.0 mg/str
Mass Air / Rev.: 495.0 mg/str

89.8% of 495 is 444 mg/str (490 is too high)

from http://forums.tdiclub.com/showpost.php?p=3906191&postcount=1

Load: 90.2 %
Load: 100.0 %
Mass Air / Rev.: 445.0 mg/str
Mass Air / Rev.: 455.0 mg/str

90.2% of 455 is 410 mg/str (455 is too high)

Matt-98AHU said:

His low pressure EGR filter is definitely clogged from a cracked DPF...
Yours is merely borderline.

Click to expand...

Thanks...

Jason,

if/when you see that MIL come back, could you post an updated P0401 error log?

(I want to see if the freeze frame changes)

Thanks

It came back yesterday and I cleared it; so far it has stayed off. I've been driving it a little more aggressively the last two days trying to force a couple regens and see if it will still do it; I've gotten 2 in the last 250 miles. When the light comes back again I'll read it with VCDS and get the details for you.

Noticed today that the DPF status went into FF40 several times, while warming up after start.

hooked up the VCDS and noted repeat (fault count increase....I did not reset the codes...)of the P0401, 70 km ago, while the car was with the dealer/body shop. it was kind of a rainy day. they may have let it idle for a while.

1 Fault Found:
001025 - EGR System
P0401 - 000 - Insufficient Flow - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 2
Fault Frequency: 4
Reset counter: 255
Mileage: 254860 km
Time Indication: 0
Date: 2000.00.00
Time: 11:04:49
Freeze Frame:
RPM: 1748 /min
Speed: 37.0 km/h
Voltage: 14.06 V
Load: 82.0 %
Load: 100.0 %
Mass Air / Rev.: 290.0 mg/str
Mass Air / Rev.: 325.0 mg/str

254930 km Vehicle Mileage

interesting that the freeze frame looks identical to the previous instance. it may not reset every time there is an occurance.

Thanks for all the information to help me identify why my 2009 JSW is throwing the P0401 code. I bought this car used July 2015 with 174000 mi. in Texas and drove it back to PA. I have no idea if this is the first or second DPF or what ECU updates have been made. The car now has 186000 mi. The P0401 code came on approx. 2000 mi ago. Since then the code has come on and off again without deleting it. Currently the code has been off for three days and used a tank of fuel. I have done nothing different except for the outside temp has been below freezing for these past 3 days. Now that this has happened i recall that the other times the code disappeared it was also close to or below 32 degrees F. Would ambient air temp have something to do with the parameters set by VW?
Tailpipe condition: little soot (5 on a scale of 10 being worst)
Odometer miles:186,000 mi
Codes recorded: [P0401, other?]
MIL?: yes and no
Basic settings EGR: N/A (No scan tool yet its in the mail.)
EGR Spec OFF/99% duty cycle/EGR (actual): N/A
EGR Spec ON/60% duty cycle/EGR (actual): N/A
OFF - On: N/A
Thanks TDI Club

I have noted that the temperature noted in Basic settings 78 is correlated to the pressure drop which seems tied to the error code.

Also, the system seems to be able to clear some of the stuff that gets caught in the EGR filter, as I see lower pressure drops at more miles since regen, and higher just after a regen.

I have not tracked against outside temps, but think it may be of interest.

and an update on my car, went over 160,000 miles Friday night

I decided to clear the codes to see if the details change with the next instance of P0401.

saw the MIL come on, but turns out it is not the P0401, but the exhaust pressure sensor whining for attention. (new sensor coming this week)

more on that error (as a side note, but it applies)

001146 - Exhaust Pressure Sensor 2
P047A - 000 - Open Circuit - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100000
Fault Priority: 2
Fault Frequency: 6
Reset counter: 255
Mileage: 257533 km
Time Indication: 0

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Temperature: 1.8°C
Temperature: 64.8°C
Temperature: 48.0°C
Pressure: 0 mbar
Pressure: 3 mbar


Readiness: 1 1 0 0 0


I followed with a check of basic settings 78, which was consistent,

but today, I checked again, and the error frequency is up to 11, and basic settings 078 did not go above 0 mbar for the pressure.

in the mean time, my polar fis displays dpf pressure as always, which tells me my problem is in the pressure sensor which is hooked up to the low pressure EGR, not the one across the DPF.

the part is not here yet, and unless it gets here before the snow flies, it will be another week or so.

I also have not seen the dpf status cycle to the FF10, which I think is tied to the NOX regen.

Luckily mine both fit in the garage

lucky man (or good planning)

Yesterday I changed out the sensor. (provided vin to the vendor, for the correct vw part. around $77 plus shipping)

there is a lot of good info related to the exhaust pressure sensors on this site, and good advice.

typical VW job, needed both a T-30 and 8mm XZN bit to access the sensor. the T-30 holds the bracket, which part way into the job I decided was in the way. nice chance to use the cable-operated clamp pliers I picked up. only one of the hoses had a clamp. I used a couple screw drivers to wedge the hoses off the sensor, and a pair of pliers to hold the hose to get the new one mated.

the sensor I changed is the one behind the oil fill.

following from alldatadiy for the 09


item 33 in the diagram is the DPF pressure senor, item1 is the low pressure EGR pressure sensor.

I know there is some confusion on folks part on which is which. (seems CJAA may have switched the routing from the CBEA) my thoughts on this are that the basic settings and various VCDS values provide evidence of which sensor is bad, and you can always unplug the sensor for a quick verification of the location of the sensor before changing it out.

took me an hour and a half, including finding tools, lights, and inspection mirror to help.


I did manage to break the electric connector detent, so it is now held onto the sensor with a couple tie-wraps.

used VCDS to reset the error, and to call for the calibration of the new sensor. ran a basic settings 78 and verified pressure readings across the low pressure EGR filter. they actually seem a bit lower.

on my drive to work this morning, my PF03 indicated a DPF status of FF40 pretty soon in the drive, but did not see the FF10. perhaps the next drive cycle.

2/2/16 saw an FF80 and several FF40, early in the drive cycles for a couple days.

follow-on 1/29. the FF10 did start next drive cycle, and today I had a chance for a longer drive.

DPF regen fired off at 16.8g soot instead of my usual 16.2. also noticed the measured soot seems to stay at 0 I was used to seeing it bounce up as the car got close to needing an active dpf regen. DPF pressure varies as does the MAF.

follow on 2/2/16 finally saw measured soot tick up. (0.6 g with 12 g calculated soot)

everything else seems good. no MIL, guess I am back to babysitting the sooty tailpipe.

Just to update I have close to 20+ DRVOLKS upgrades EGR test filters on the road now.
Not one has come back with a P0401 code.
I see the cost for a new DPF has gone up by $200 from last summer WOW.
With this VW scandal dragging on people with a check engine light on and a P0401 you get a reject sticker.
Will VW scrap ever thing from to the turbo back and upgrade??

since my wife broke a couple bones, we are not headed to ski on weekends, so I had some time to look at more of the Basic settings 78 data.



the blue diamonds are all from my car, and the blue square is data point closest to my few P0401 errors.

the red square is from dubfamily's car. (who had P0401 errors and MIL lit)

Yellow squares are from maintenance247, the one between the blue and red square is from November, and the two under the red square are from last week, with a bad DPF. The dealer changed out the DPF and EGR filter under warranty.

The yellow square with green boarder is a reading with the new DPF installed.

I put a version of this chart in the first post.

CNGVW said:

Just to update I have close to 20+ DRVOLKS upgrades EGR test filters on the road now.
Not one has come back with a P0401 code.
I see the cost for a new DPF has gone up by $200 from last summer WOW.
With this VW scandal dragging on people with a check engine light on and a P0401 you get a reject sticker.
Will VW scrap ever thing from to the turbo back and upgrade??

Click to expand...

Bob,

Could you run basic settings 78 on a couple of these cars, before and after? (on the next ones, anyway?)

Thanks.

Shore will for you. I will test my wife car some time this week.

Thanks!

Hi all, unfortunately I don't have VCDS to log all the data (got to fix laptop before buying) I do have an OBD code reader though.
Brief history: 2013 TDI JSW manual trans: MIL light on got P047F code for exhaust flap (around 65kish miles), finally had it replaced by the dealer in January when I had annual inspection as well as the 2306 update, (75k miles).
End of February got MIL light again, codes P2413, P2000 and P2002. Dealer replaced DPF under warranty.
2 weeks ago MIL light back on, codes P2413, P2000 and P2002, trying to figure out when I can take it back into the dealer. Decent amount of soot in EGR line and in EGR but does not appear clogged (I was unable to remove egr due to running out of daylight)
My tailpipe is very sooty and under some instances of hard acceleration I can see a small light cloud of black smoke. Not sure when the soot started but I believe it was before the DPF was replaced by the dealer and after the 2306 update.

Hope you are still under 80,000 miles. if not, I would still head back to the dealer ASAP. one would suspect they messed up the fix for a DPF have issues so soon after they replaced it.

Did you check the low pressure EGR (rear of car) or the high pressure EGR (front of car)

a new DPF should let zero soot out the tailpipe.

meerschm said:

Hope you are still under 80,000 miles. if not, I would still head back to the dealer ASAP. one would suspect they messed up the fix for a DPF have issues so soon after they replaced it.

Did you check the low pressure EGR (rear of car) or the high pressure EGR (front of car)

a new DPF should let zero soot out the tailpipe.

Click to expand...

Yes, I'm still under 80k, trying to coordinate with the dealer to take it in.
The EGR i checked was the high pressure one, right between the ASV and the intake manifold. Is the low pressure one behind the engine near the DPF?

Yes I know a new DPF shouldn't let any soot out, but shouldn't any properly functioning dpf do that?

Correct, but this whole thread is about those of us with a DPF that is not so perfect, and seeps some soot.

and also yes.. the EGR in front is high pressure EGR, allows some exhaust from before the turbo to enter the intake. some soot should be expected there.

the low pressure EGR feeds earlier in the path, before the air side of the turbo compresses the air. it is supposed to be clean.

http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf

see page 46 if you like.

Thanks!

Hey Mike, just wondering on something:

As I have updated mine to a 2010+ 2 piece DPF last August, I'm hoping I'll be good for a while.

Do you think removing the LP EGR filter yearly (about 1-2 hours labor) and having it hot-tanked/cleaned will help the DPF breathe better ?

I know you're the master when it comes to questions on the DPF.

I just want to prevent another expensive repair. The first time I got my P0401 and was diagnosed as a cracked/clogged DPF I drove around for quite a while with P0401 yet noticed no difference in how the car ran with or without replacing the DPF. I think the DPF regens still take place even if it is cracked and soot just passes.

Hate to say but I may have taken the dealer's bait on a 2010 rebuild. I know they say its PM, that a persistent P0401 may eventually cause the car to go into limp mode, but my car was running fine even with a cracked DPF.

My symptoms last year were a clogged EGR filter, which I'm wondering if cleaned or hottanked may prevent DPF damage.

Any thoughts, thanks

Cal

My DPF thread last year:

http://forums.tdiclub.com/showthread.php?t=442459

Mechanic said a clogged/cracked DPF cannot lead to engine damage, but car may go into limp mode, which never happened to my car, it ran fine even with cracked DPF

Thanks for the nice words, Cal. I just read the book, and asked a couple questions.

if it was me, I would not touch that LP egr filter. more likely to break something than do any good.

with a new DPF, (or any time one is not cracked) there should be no soot getting anywhere near the LP EGR filter, so no reason to take it off.

I would not pull it apart to look at it. Remember the issue that got you your car is that the DPF cracks, soot leaks past, which clogs the LP EGR filter. (not the other way around)

A glance at the tailpipe should do the trick. With your new DPF, the tailpipe should not be seeing any new soot. if you clean it up, should be able to keep an eye on it.

As far as how to treat it to avoid the crack and expensive fix in the future, that is a good question. Not sure what really causes them to crack sometimes. There was some guessing that the patch VW put out prior to the dieselgate mess was meant to reduce cracks in the DPF, and not the NOX reduction attempt. They never released the patch for the 2009, which is just as well, as it turns out.



We figured out you can use VCDS to run basic settings test 78 to watch that low pressure egr filter, but if you tailpipe is staying clean, I think you are good to go.

I am still watching mine, the tailpipe is a little sooty, but the basic settings 78 values reads in the good range. I only saw P0401 once, after a few-hour-long bumper to bumper slog in the cold rain. it never caused a MIL for me.

At 163,000 miles, so far so good.

Anytime Mike, I should of remembered that. The LP EGR filter catches the soot and prevents it from traveling further downstream where it may cause more contamination, right ?

My concern was that the EGR filter somehow catches a little soot every now and then even with a healthy DPF, which I'm gathering should not be the case.

It's been over 11,000 trouble free miles so far on the new DPF, I'm at 133K now.

I bought my TDI used at 63k miles so I have no way of knowing how the prior owner's driving habits were. I am guessing that driving the CR TDIs in traffic make DPFs more problem prone. A VW mechanic I spoke to told me they get 2015s sometimes with DPF problems sometimes from people that ignore the DPF light and don't go on the highway run.

These TDIs, like any car, like the highway and I've got a feeling short errand running without adequate regens may be a culprit. The most I'll ever go without a highway run (2000 RPMs for 20 min) is usually 2 days.

Mechanics final recommendations to me were to change the fuel filter every 20K, air filter every 40K or as needed, only use 507 grade oil and fresh busy diesel station.

Will not touch the LP EGR filter, thanks for the warning.

The low pressure EGR filter (called a tube in some parts diagrams) lets some of the exhaust which has had soot removed by the DPF pass to the low pressure EGR cooler, and into the clean air side of the turbocharger. this filtered exhaust joins fresh air, and is then compressed by the turbo.

http://www.natef.org/NATEF/media/NATEFMedia/VW Files/2-0-TDI-SSP.pdf

there is a good figure on page 58 the low pressure egr filter is not shown, but it connects to the bottom of the DPF, before the NOX cat.

Glad your car is running fine. Hope it gives you many years of happy service.

Well, here it is and I still am driving around with a sooty pipe and no errors. I did get the car emissions inspected, with the clean OBD, so I can renew the plates in Sept even if the P0401 error shows up and for some reason I do not want to fix right away.

A couple weeks ago, I gave the inside of the tailpipe a shot of brake cleaner and wiped it out. It stayed pretty clean for a while, but after a couple DPF regen cycles, is back to a slightly sooty state.

The car has 165,000 mile now, or around 40k with at least some soot beyond the DPF.

Basic settings 078 is staying well on the left side of the graph I came up with, not close to what seems to cause the P0401 error.

Ok, update on my saga.
Got the car back Friday night after 2.5 weeks at the dealer. They have been having a hard time diagnosing the problems and been communicating with VW Techline. After replacing the low pressure EGR filter twice under warranty, fixing a vacuum leak and replacing the DPF again, they told me it was fixed. Drove it a little bit this weekend and i put a catback on it (clearance deal on the Banks unit, couldn't pass it up), no issues. No codes, runs great!

Today at lunch went out and check engine light is back on, check codes and I have P0101 Map, P2002 DPF efficiency and P2459 Regen frequency all showing as pending codes.
Could this have anything to do with the catback I installed? I did pull the exhaust flap motor and NOX converter during the install but everything went back together smoothly and no leaks (that I can hear/see anyways).

Someone else posted a similar error, and story that a dealer tech thought it was related to less backpressure.

I would suspect the mass air flow, either sensor, or a wire. The mass flow is used as part of the measured soot reading. and the soot reading can call for DPF regeneration.

you might want to check and perhaps log the calculated and measured soot, DPF pressure, and miles since regen. mass air flow should also be a good choice to log.