Just read your posts about PIDs, if you need a hand to process your csvs don't hesitate ! we can maybe come up with a standardized processing. I'll do it with with mine from mmi's torque config and post it when I have some time
[T6_measured] Monitoring DPF regeneration, DPF condition, EGR operation
- Thread starter mmi
- Start date
-
- Tags
- dpf egr t6_measured
The DPF itself is quite "tight" being a filter but assuming the SCR catalyst wouldn't restrict much in any case.
How high is "high" differential pressure - engine idling? More than 15 mbar?
There can be quite a lot of variation - depending at least e.g. on EGR position, on DPF soot fill level, DPF ash level, DPF temperature (huge effect).
Thank you very much for your log file - a good sample of 3135 seconds of "normal" engine operation and 1165 seconds of DPF regeneration at fairly high speed. Also quite intriguing part is the high rev section inside DPF regen - need to compare soot burn rates vs. "normal" revs 
I think in this sample the "high" differential pressures are because of DPF regeneration.
During the regen the EGR valve is closed - thus no exhaust recirculation - all the air that is sucked into engine goes eventually to exhaust along expanding combustion gases from cylinders. In addition to that during DPF regen into exhaust stream an extra dose of diesel is injected which then will be combusted in the catalytic converter - thus further expanding exhaust stream - all this hot gas will be fed into DPF - to finally burn soot off - again contributing to expansion of exhaust gases. Thus quite a stream of hot gases through the DPF - creating a significant the pressure loss across the DPF. As the DPF itself can't strech or expand - the more gas flow - the more pressure loss.
Would be interesting to calculate ratio of air intake mass flow vs. DPF differential pressure
(a) before DPF regen, e.g. from 2800 to 3130 seconds (EGR operational)
(b) during hot phase of DPF regen, e.g. from 3250 to 3600 seconds (EGR off)
Everything, including differential pressure, are similar what I have observed on my T6.
I think in this sample the "high" differential pressures are because of DPF regeneration.
During the regen the EGR valve is closed - thus no exhaust recirculation - all the air that is sucked into engine goes eventually to exhaust along expanding combustion gases from cylinders. In addition to that during DPF regen into exhaust stream an extra dose of diesel is injected which then will be combusted in the catalytic converter - thus further expanding exhaust stream - all this hot gas will be fed into DPF - to finally burn soot off - again contributing to expansion of exhaust gases. Thus quite a stream of hot gases through the DPF - creating a significant the pressure loss across the DPF. As the DPF itself can't strech or expand - the more gas flow - the more pressure loss.
Would be interesting to calculate ratio of air intake mass flow vs. DPF differential pressure
(a) before DPF regen, e.g. from 2800 to 3130 seconds (EGR operational)
(b) during hot phase of DPF regen, e.g. from 3250 to 3600 seconds (EGR off)
Thank you ! I forgot that log was in regen mode, when not in regen it is still high, I suspect sticky soot in the DPF. I still have to automate an analysis as well.Thank you very much for your log file - a good sample of 3135 seconds of "normal" engine operation and 1165 seconds of DPF regeneration at fairly high speed. Also quite intriguing part is the high rev section inside DPF regen - need to compare soot burn rates vs. "normal" revs
Everything, including differential pressure, are similar what I have observed on my T6.
I think in this sample the "high" differential pressures are because of DPF regeneration.
During the regen the EGR valve is closed - thus no exhaust recirculation - all the air that is sucked into engine goes eventually to exhaust along expanding combustion gases from cylinders. In addition to that during DPF regen into exhaust stream an extra dose of diesel is injected which then will be combusted in the catalytic converter - thus further expanding exhaust stream - all this hot gas will be fed into DPF - to finally burn soot off - again contributing to expansion of exhaust gases. Thus quite a stream of hot gases through the DPF - creating a significant the pressure loss across the DPF. As the DPF itself can't strech or expand - the more gas flow - the more pressure loss.
Would be interesting to calculate ratio of air intake mass flow vs. DPF differential pressure
(a) before DPF regen, e.g. from 2800 to 3130 seconds (EGR operational)
(b) during hot phase of DPF regen, e.g. from 3250 to 3600 seconds (EGR off)
View attachment 207804
I attached an other log if you are curious.
I just drove 1600km to go to Spaim I have many logs
Thanks again.
Well, still can't see any problem with the DPF. It's just that the more air engine ingests the more exhaust flow it creates. Is the DPF a new one - as the ash mass is very low for the mileage of the vehicle?
Just an interesting detail - obviously there was quite a downhill (2.5 km) from 425 to 510 seconds as the DPF cooled down to 170 C while vehicle maintaining steady speed.
Well, still can't see any problem with the DPF. It's just that the more air engine ingests the more exhaust flow it creates. Is the DPF a new one - as the ash mass is very low for the mileage of the vehicle?
Just an interesting detail - obviously there was quite a downhill (2.5 km) from 425 to 510 seconds as the DPF cooled down to 170 C while vehicle maintaining steady speed.
Found this nice graph - don’t look at the scales at all as this is for some large marine engines. But it shows the pressure drop in DPF is dependent on the temperature as well as the flow rate.
As to why temperature affects the pressure drop, the article [1] offers this easy-to-understand explanation: ”Under the same flow rate condition, the pressure change increases as the temperature increases because the DPF carrier cordierite expands as the temperature increases and the filter porosity decreases. ”
[1] Modeling Differential Pressure of Diesel Particulate Filters in Marine Engines
Thanks ! Interesting indeed ! My DPF is not new, it is probably damaged (P226D) the low oil ash might be because of a garage doing an adaptation of someting like that with OBD2 device to see if the P226D stops.
I have done some correlation analysis and indeed differential pressure seems strongly tied to air mass intake which is logical, here are the results with my t6's data :
the closest to 1, the more correlated it is, meaning a link between the 2 data.
To sum up the top correlations (outside of exhaust temps between them) are :
- Correlation between T6-01 DPF Differential pressure(mbar) and T6-01 Air intake mass flow(g/s): 0.9371952278427615
- Correlation between T6-01 Air intake mass flow(g/s) and T6-01 Engine RPM(1/min): 0.7655275977223092
- Correlation between T6-01 DPF Differential pressure(mbar) and T6-01 Engine RPM(1/min): 0.7070677876359647
- Correlation between T6-01 DPF Soot mass (measured)(g) and T6-01 DPF Distance since last regen(km): 0.6967268586275546
I am still mangling the data if you have ideas of analysis to do I am open to it !
One that I would love to do would require data from different cars to analyze the deviation of data and compare it between different cars, engines, mileages etc...
Nice! That correlation map is pretty interesting way of looking into the data - takes little bit of staring to get acquainted with the color scheme but pretty intuitive in the end.
What really stands out to me is that EGR position does not correlate with any of the measured variables. I find that ”two sided” range somewhat suspicious - maybe there’s some error in the value interpretation from binary. Or could it perhaps be a gradient command, like ”open/close valve slow/fast” rather than an actual position? Hmm.. not sure.
I don’t think these metrics are useful in solving the case though
. The values look normal… and soot in tailpipe tells DPF is not doing it’s thing properly. Have you cleaned the tailpipe and observed it’s still getting black?I’m by no means an expert but if the DPF was cracked I would expect the pressure difference to be on a low side, and high if it was clogged.
Also I’m wondering about particle sensor… where does the engine come up with that code? It’s kind of contradicting if the particle sensor doesn’t record anything but there’s soot Weird T6 Problems - Solved
Thank you @ebiii @n10n very much for your involvement and enthusiasm on data analysis.
I'm inclined to be believe it's indeed two-sided EGR operation. I seem to get either positive or negative cycles.
Below examples... please note the "EGR dance" (as in post #34) at the end of data - engine stopped by Stop/Start button to keep data logging alive.
Average EGR position +31%.
Average EGR position -39%.
Yes, that's indeed an interesting feature. I did double check at the time that it coincides with VCDS data (not meaning the VCDS is the absolute truth). Also verified that the generic OBD EGR position is actually absolute value of this two sided value.
I'm inclined to be believe it's indeed two-sided EGR operation. I seem to get either positive or negative cycles.
Below examples... please note the "EGR dance" (as in post #34) at the end of data - engine stopped by Stop/Start button to keep data logging alive.
Average EGR position +31%.
Average EGR position -39%.
The sign obviously means something… one thought is that maybe the flap indeed can turn both ways from the closed position and both directions are used, not as functionally significant but just in an effort to try keep wear and clogging symmetric - perhaps thus improving valve lifetime a bit. Pure speculation though.
A bit surprising these don't correlate better. What about T6-01 DPF soot mass (calculated) with the distance?
Also noticed interesting/different behaviour of the T6-01 DPF soot mass (measured). On your data 30.7.2023 the value is quite stable.
Perhaps it's the driving profile for the log - fairly high speed thus fairly hot exhaust gases into DPF - inducing noticeable passive DPF regeneration.
Well, in post #3 I thought there is at least some correlation with engine RPM (vehicle speed) on a gear - basically correlation with engine load because of a significant change in aerodynamic drag.
I think the van wasn't driven long enough for the sensor actually being in operation.
Then I mentioned that iIt usually takes 15 minutes before the counter starts ticking. However, there seems to more involved.
By glancing through a few logs - a quite typical behaviour is as below. From start-up at 15-25 minutes two 10-minute activity "bursts",
Code:
2022-02-11 IDE08721 Particle sensor: time in op. mode measurement
14:35:22 0
14:37:27 0
14:38:46 0
14:39:39 0
14:40:56 0
14:42:04 0
14:43:11 0
14:44:19 0
14:45:27 0
14:46:31 0
14:47:43 0
14:48:53 0
14:49:55 0
14:51:06 58.5
14:52:14 126.2
14:53:21 193.9
14:54:30 261.8
14:55:38 329.6
14:56:46 397.4
14:57:53 465.6
14:58:58 0
15:00:17 0
15:01:11 61.9
15:02:27 130.5
15:03:31 198.3
15:04:47 265.9
15:05:43 333.6
15:07:02 401.6
15:08:01 469.4
15:09:14 537.4
15:10:21 0
15:11:29 0
15:12:36 0
15:13:43 0
15:14:52 0
15:16:02 0
15:17:06 0
15:18:15 0
15:19:24 0
15:20:32 0
15:21:39 0
15:22:47 0
15:23:54 0
15:25:01 0
15:26:11 0
15:27:17 0
15:28:27 0
15:29:29 0
15:30:41 0
15:31:50 0
15:32:53 0
15:34:05 0
15:35:12 0
15:36:20 0
15:37:27 0
15:38:35 0
15:39:43 0
15:40:51 0
15:41:58 0
15:43:07 0
15:44:56 0
15:46:10 0
Code:
2022-02-22 IDE08721 Particle sensor: time in op. mode measurement
16:42:13 0
16:43:30 0
16:45:42 0
16:46:42 0
16:47:54 0
16:49:03 0
16:50:09 0
16:51:17 0
16:52:23 0
16:53:43 0
16:54:29 0
16:55:44 0
16:57:03 0
16:57:56 0
16:59:22 0
17:00:21 0
17:01:29 27.5
17:02:37 95.1
17:03:44 162.7
17:04:51 230.6
17:05:59 298.5
17:07:09 367
17:08:15 435
17:09:21 502.8
17:10:32 0
17:11:39 35.6
17:12:44 104.6
17:14:03 172.5
17:14:56 240.5
17:16:16 308.3
17:17:26 376.2
17:18:14 443.9
17:19:39 511.9
17:20:47 0
17:21:44 0
17:23:10 0
17:24:00 0
17:25:04 0
17:26:32 0
17:27:24 0
17:28:39 0
17:29:46 0
17:30:55 0
17:32:04 0
17:33:08 0
17:34:23 0
17:35:18 0
17:36:38 0
17:37:39 0
17:38:52 0
17:39:54 0
17:41:07 0
17:42:15 0
17:43:18 0
17:44:28 0
17:45:41 0
17:46:45 0
17:50:59 0
17:52:10 0
17:53:10 0
17:54:25 0
17:55:30 0
17:56:39 0
Code:
2022-06-08 IDE08721 Particle sensor: time in op. mode measurement
08:52:02 0
08:53:37 0
08:54:38 0
08:55:53 0
08:56:59 0
08:58:04 0
08:59:15 0
09:00:22 0
09:01:29 0
09:02:37 0
09:03:45 0
09:04:53 0
09:06:02 40
09:07:10 107.6
09:08:16 175.2
09:09:24 243.5
09:10:32 311.1
09:11:38 378.6
09:12:47 446
09:13:54 0
09:15:03 5.2
09:16:10 72.7
09:17:18 140.3
09:18:25 208
09:19:32 275.5
09:20:40 343.1
09:21:44 410.4
09:22:55 0
09:24:04 0
09:25:11 0
09:26:19 0
09:27:26 0
09:28:33 0
09:29:43 0
09:30:46 0
09:31:57 0
09:33:05 0
09:34:12 0
09:35:20 0
09:36:28 0
09:37:35 0
09:38:42 0
09:39:52 0
09:40:54 0
09:42:06 0
09:43:15 0
09:44:21 0
09:45:29 0
09:46:39 0
09:47:41 0
09:48:52 0
09:50:00 0
09:51:07 0
09:52:15 0
09:53:25 0
09:54:27 0
09:55:37 0
09:56:44 0
09:57:53 0
09:59:01 0
10:00:08 0
10:01:17 0
10:02:26 0
10:03:30 0
10:04:44 0
10:05:40 0
10:06:57 0
10:08:06 0
10:09:10 0
10:10:19 0
10:11:27 0
10:12:35 0
10:13:56 0
10:15:03 0
10:16:11 0
10:17:21 0
10:18:23 0
10:19:40 0
10:20:33 0
10:21:54 0
10:22:54 0
10:24:09 0
10:25:07 0
10:26:24 0
10:27:26 0
10:28:33 0
10:29:43 0
10:30:52 0
10:31:55 0
10:33:06 0
10:34:14 0
10:35:21 0
10:36:26 0
10:37:37 0
10:38:44 0
10:39:53 0
10:41:00 0
10:42:09 0
10:43:12 0
10:44:23 0
10:45:31 0
10:46:38 0
10:47:45 0
10:48:50 0
10:50:01 0
10:51:10 0
10:52:12 0
10:53:30 0
10:54:48 0
10:56:06 0
10:57:10 0
10:58:31 0
10:59:47 0
11:00:47 0
11:02:41 0
11:03:50 0
Last edited:
Seems pretty odd but apparently the particle sensors themselves need to be regenerated:
”Prior to each measurement phase, the sensor element is regenerated through heating so that the sensor element adopts a defined status before the start of the measurement process.”
Particulate matter sensor
The particulate matter sensor is used to monitor the function of the diesel particle filter (DPF).
www.bosch-mobility.com
Would the measurement cycles coinside with DPF regens perhaps?
Apologies, made a mistake when concatenating log files - didn't realise they were two separate log files (now split correctly)
Thus, seems there is only one measurement period per driving cycle.
No, DPF regen is more rare event. However, obviously need to find a log of a DPF regen.
Ok, then it’s probably once per trip when engine is up to temp.
Pretty interesting way to measure anyway! I guess it’s good enough for the purpose, if the DPF starts letting soot through it’s still going to do it on the next run and probably nothing could be saved by having a fault logged more promptly.
Take 2 - brought a few obviously related parameters along the same time axis as earlier.
The exhaust temperature sensor S4 should be near the particle sensor. I would expect the IDE08340 be the indicator of detected soot. Obviously need to provide an update for Torque settings to @ebiii
| IDE08721 | IDE08340 | IDE07984 | IDE09420 | IDE07990 | IDE07987 | IDE04090 | |
| 2022-02-11 | Particle sensor: time in op. mode measurement | Particle sensor: measuring current calculated [µA] | Particle sensor: cleaning deviation reaction time | Heat quantity for dewpoint end: particle sensor | Particle sensor: surface temperature | Particle sensor: exhaust temperature | Exhaust temperature /S1/S2/S3/S4 |
| 14:35:22 | 0 | 0 | 0 | 0 | 13.8 | -0.4 | /8/-13/-15/-13 °C |
| 14:37:27 | 0 | 0 | 0 | 0 | 198.8 | 0.3 | /201/64/35/1 °C |
| 14:38:46 | 0 | 0 | 0 | 0 | 200.8 | 4.6 | /196/102/83/69 °C |
| 14:39:39 | 0 | 0 | 0 | 0 | 200.8 | 4.7 | /321/150/101/66 °C |
| 14:40:56 | 0 | 0 | 0 | 0 | 198.8 | 5 | /368/189/155/66 °C |
| 14:42:04 | 0 | 0 | 0 | 0 | 200.8 | 7 | /360/221/202/83 °C |
| 14:43:11 | 0 | 0 | 0 | 0 | 200.8 | 11.2 | /461/261/236/142 °C |
| 14:44:19 | 0 | 0 | 0 | 0 | 198.8 | 14 | /306/266/272/188 °C |
| 14:45:27 | 0 | 0 | 0 | 0 | 200.8 | 19.3 | /421/303/297/235 °C |
| 14:46:31 | 0 | 0 | 0 | 0 | 198.8 | 20.3 | /305/282/297/258 °C |
| 14:47:43 | 0 | 0 | 0 | 0 | 200.8 | 20.3 | /473/305/293/270 °C |
| 14:48:53 | 0 | 0 | 0 | 100 | 317.8 | 20.5 | /349/282/301/265 °C |
| 14:49:55 | 0 | 0 | 0 | 100 | 608.8 | 21.9 | /540/334/281/270 °C |
| 14:51:06 | 58.5 | 0 | 0.109 | 100 | 198.8 | 22.8 | /410/312/314/290 °C |
| 14:52:14 | 126.2 | 0 | 0.272 | 100 | 195.8 | 22.2 | /409/314/315/288 °C |
| 14:53:21 | 193.9 | 0 | 0.446 | 100 | 189.8 | 22.1 | /412/304/297/287 °C |
| 14:54:30 | 261.8 | 0 | 0.608 | 100 | 180.8 | 20.9 | /447/301/294/276 °C |
| 14:55:38 | 329.6 | 0 | 0.768 | 100 | 186.8 | 21.7 | /435/295/281/272 °C |
| 14:56:46 | 397.4 | 0 | 0.937 | 100 | 198.8 | 22.6 | /447/318/319/286 °C |
| 14:57:53 | 465.6 | 0 | 1.126 | 100 | 198.8 | 22.6 | /430/306/300/291 °C |
| 14:58:58 | 0 | 0 | 0 | 100 | 504.8 | 22.4 | /415/305/300/280 °C |
| 15:00:17 | 0 | 0 | 0 | 100 | 488.8 | 23 | /504/325/306/284 °C |
| 15:01:11 | 61.9 | 0 | 0.113 | 100 | 207.8 | 23.2 | /443/312/309/293 °C |
| 15:02:27 | 130.5 | 0 | 0.271 | 100 | 207.8 | 22.8 | /448/318/315/290 °C |
| 15:03:31 | 198.3 | 0 | 0.421 | 100 | 191.8 | 21.9 | /334/297/302/288 °C |
| 15:04:47 | 265.9 | 0 | 0.583 | 100 | 195.8 | 21.6 | /442/304/294/279 °C |
| 15:05:43 | 333.6 | 0 | 0.745 | 100 | 186.8 | 21.6 | /424/298/294/275 °C |
| 15:07:02 | 401.6 | 0 | 0.889 | 100 | 183.8 | 20.5 | /382/299/295/272 °C |
| 15:08:01 | 469.4 | 0 | 1.073 | 100 | 180.8 | 19.9 | /456/299/288/271 °C |
| 15:09:14 | 537.4 | 0 | 1.253 | 100 | 175.8 | 20.3 | /339/282/268/265 °C |
| 15:10:21 | 0 | 0 | 0 | 100 | 283.8 | 20.3 | /353/307/311/266 °C |
| 15:11:29 | 0 | 0 | 0 | 100 | 287.8 | 20.2 | /347/299/288/282 °C |
| 15:12:36 | 0 | 0 | 0 | 100 | 280.8 | 20.8 | /439/307/289/267 °C |
| 15:13:43 | 0 | 0 | 0 | 100 | 275.8 | 22.8 | /389/303/301/272 °C |
| 15:14:52 | 0 | 0 | 0 | 100 | 293.8 | 21.5 | /247/283/318/289 °C |
| 15:16:02 | 0 | 0 | 0 | 100 | 290.8 | 21.2 | /251/260/271/293 °C |
| 15:17:06 | 0 | 0 | 0 | 100 | 280.8 | 18.9 | /367/285/282/253 °C |
| 15:18:15 | 0 | 0 | 0 | 100 | 272.8 | 19.6 | /372/290/284/254 °C |
| 15:19:24 | 0 | 0 | 0 | 100 | 274.8 | 21 | /396/306/321/265 °C |
| 15:20:32 | 0 | 0 | 0 | 100 | 287.8 | 20.4 | /434/301/290/282 °C |
| 15:21:39 | 0 | 0 | 0 | 100 | 280.8 | 21 | /400/299/291/270 °C |
| 15:22:47 | 0 | 0 | 0 | 100 | 275.8 | 20.4 | /394/288/279/265 °C |
| 15:23:54 | 0 | 0 | 0 | 100 | 275.8 | 19.2 | /214/236/271/257 °C |
| 15:25:01 | 0 | 0 | 0 | 100 | 268.8 | 18.2 | /453/283/260/254 °C |
| 15:26:11 | 0 | 0 | 0 | 100 | 267.8 | 18.5 | /421/278/262/239 °C |
| 15:27:17 | 0 | 0 | 0 | 100 | 269.8 | 18.1 | /378/284/275/245 °C |
| 15:28:27 | 0 | 0 | 0 | 100 | 264.8 | 18.4 | /406/285/272/245 °C |
| 15:29:29 | 0 | 0 | 0 | 100 | 272.8 | 17.2 | /302/261/272/242 °C |
| 15:30:41 | 0 | 0 | 0 | 100 | 264.8 | 18 | /390/276/254/245 °C |
| 15:31:50 | 0 | 0 | 0 | 100 | 262.8 | 17.7 | /463/291/271/237 °C |
| 15:32:53 | 0 | 0 | 0 | 100 | 259.8 | 19.4 | /404/297/286/242 °C |
| 15:34:05 | 0 | 0 | 0 | 100 | 272.8 | 20.9 | /397/291/289/267 °C |
| 15:35:12 | 0 | 0 | 0 | 100 | 272.8 | 21.1 | /455/293/283/269 °C |
| 15:36:20 | 0 | 0 | 0 | 100 | 274.8 | 22.7 | /486/310/299/273 °C |
| 15:37:27 | 0 | 0 | 0 | 100 | 285.8 | 22.8 | /235/268/284/284 °C |
| 15:38:35 | 0 | 0 | 0 | 100 | 287.8 | 20.1 | /167/225/288/269 °C |
| 15:39:43 | 0 | 0 | 0 | 100 | 282.8 | 18.9 | /168/215/258/265 °C |
| 15:40:51 | 0 | 0 | 0 | 100 | 282.8 | 18.1 | /214/192/185/237 °C |
| 15:41:58 | 0 | 0 | 0 | 100 | 269.8 | 17.6 | /334/228/217/223 °C |
| 15:43:07 | 0 | 0 | 0 | 100 | 264.8 | 15.7 | /343/236/212/195 °C |
| 15:44:56 | 0 | 0 | 0 | 100 | 264.8 | 15.5 | /300/210/210/198 °C |
| 15:46:10 | 0 | 0 | 0 | 100 | 272.8 | 15 | /173/180/199/194 °C |
Note: The snippet is an extract of a continuous recording stream of all engine parameters thus the sampling rate is quite slow (once per 70 seconds - because of 1495 parameters being recorded).
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