Exhaust back pressure and DPF pressure differential data

painej

New member
I own a 2007 Dodge Sprinter, 3.0 L V6 (diesel) engine, with just a tad over 300k mi. The CEL is lit. Using the Autel 808, the code is P2626 with no other codes. I just did a test drive while recording exhaust back pressure and differential pressure at differing engine speeds. I've done a pretty extensive online search, but haven't seen much hard information on expected values for an operational DPF. Here mine are, in case anyone would like to weigh in on where these fall relative to a "normal" range:
At idle (770 rpm): exhaust back pressure 1201 hPa (17 psi); DPF differential pressure 12 hPa (0.2 psi).
At 2910 rpm: exhaust back pressure 1750 hPa (25 psi); DPF differential pressure 43 hPa (0.6 psi).
I've seen back pressures as high as 2070 hPa (30 psi) and differential pressures as high as 63 hPa (0.9 psi).

So the question is: do these numbers suggest a clogged DPF? I recently replaced the dpf pressure sensor for unreasonable reported values, and it appears to be functional now. The van runs well, is regularly getting 20-21 mpg, and isn't in limp mode. The ECU is reporting ash content at 0 (seems unrealistic) and soot content at 0.6 g/l.

Thanks in advance for any guidance or links to other discussions I might have missed! I know this is a well-worn general topic among Sprinter owners.
 
Last edited:

Kajtek1

2015 long/tall limo RV 2.1l
I admire you drive to record this data and to date you are the 1st one I see doing it.
From my experience with scanners, they can have big error margins, so I would not draw conclusions till 2nd scanner confirms the data.
For example Torque Pro shows my sedan backpressure at 3000 psi. I know 3000 psi from my scuba activity, so don't think it is possible on the car.
Bottom line, even I still have Torque Pro, I did not bother to try it on Sprinter.
 

painej

New member
What are the pressure readings with the key ON but engine OFF? (KOEO)
About what you would expect for central Texas; pretty much atmospheric for exhaust back pressure (960 or so hPa, I think) and 0 hPa for differential pressure.
 

painej

New member
I admire you drive to record this data and to date you are the 1st one I see doing it.
From my experience with scanners, they can have big error margins, so I would not draw conclusions till 2nd scanner confirms the data.
For example Torque Pro shows my sedan backpressure at 3000 psi. I know 3000 psi from my scuba activity, so don't think it is possible on the car.
Bottom line, even I still have Torque Pro, I did not bother to try it on Sprinter.
Could your Torque Pro pressure units be 3000 hPa instead? At 69 hPa per psi, your number would work out to about 44 psi, which is a little higher than mine.
 

manwithgun

Active member
My guess would be that the previous owner "cored" out the DPF as the differential pressure seems low. Have a look at this thread:

Edit: Another issue that causes inaccurate differential pressure values is when the plumbing to the sensor becomes clogged. Both the rubber and stainless tubing at each end of the DPF (connected to sensor) must be clear and able to pass air. And the sensor itself has also seen a revision in recent years.
 
Last edited:

showkey

Well-known member
The torque APP scan “tool” is infamous of pressure reading problems......there other forums report erratic or irrational Pressure reading on Toyotas and half dozen other manufacturers......specifically in unit error.
 

Bobnoxious

GONE FISHING
Won't take much of a leak to throw erroneous sensor data.

Standard shop practice, clamp all connections. Especially related to emissions controls.


IMG_9779.PNGIMG_2469.JPG
 
  • Thanks
Reactions: JFM

painej

New member
Thanks all for the comments and suggestions. I'm the original owner, so I know the DPF hasn't been cored. I recently removed it to have it baked when the clogged code appeared (it's the original DPF), and reinstalled it afterward without apparent problems or damage. I thoroughly cleaned the hoses and tubing at the time.

I have new data today, this time under load (hard acceleration and hill climb; the numbers below are the highest ones I recorded).

At 2780 rpm and 2300 hPa (33 psi) boost pressure:
Exhaust back pressure 3210 hPa (47 psi)
Differential DPF pressure 119 hPa (1.7 psi)

A local shop (good mechanics but not Sprinter experts) installed the new DPF differential pressure sensor while trying to diagnose the problem, so this weekend I'll crawl under there to make sure the hoses are properly clamped and not leaking.
 
Last edited:

Dima74

Independent & Self Reliant - From Chattanooga TN
Thanks all for the comments and suggestions. I'm the original owner, so I know the DPF hasn't been cored. I recently removed it to have it baked when the clogged code appeared (it's the original DPF), and reinstalled it afterward without apparent problems or damage. I thoroughly cleaned the hoses and tubing at the time.

I have new data today, this time under load (hard acceleration and hill climb; the numbers below are the highest ones I recorded).

At 2780 rpm and 2300 hPa (33 psi) boost pressure:
Exhaust back pressure 3210 hPa (47 psi)
Differential DPF pressure 119 hPa (1.7 psi)

A local shop (good mechanics but not Sprinter experts) installed the new DPF differential pressure sensor while trying to diagnose the problem, so this weekend I'll crawl under there to make sure the hoses are properly clamped and not leaking.
First... Why was the pressure sensor changed?

Based on what you stated/described so far, I think you do have a dpf that is lived its life and it needs to be replaced. You took it to a shop (you did not clearly state why) where the good guys replaced the pressure difference sensor in trying to see if that is the fix for the problem. What more likely happened is, the good guys did reset the ash value to 0 after replacing the pressure difference sensor and now you have a situation where the ECU has a 0 value for the ash level that does not correspond to the pressure difference that the ECU is reading, throwing a red flag at you with the code 2626. The ash value is calculated in the total fill level of the DPF and in this case that I describe the total fill level/value does not correspond/match to the pressure difference read by the ECU. Does that make sence?... Ask the good guys to explain you what they did exactly after they changed the sensor. Did they do any teach-in or initialization?

I think (not sure 100%) the way the ash level/value is calculated is per number of regenerations. One regeneration has a fix value or amount of ash figured and that value is multiply by how many regenerations have occurred. If one regeneration creates .01 grams of ash, .01 x 100 (as an example) = 1 gram of ash. I think that is how the ash level/value is calculated, since the dpf itself does not have anything that can distinguish between soot and ash in its system. Make sense?

Now... When the value is set to 0 but the dpf is still old, pressure difference vs total fill level, will throw everything out of the specified/programmed parameters.

One more thing, if someone here gives you any data to you for comparison, it must be from a non-bluetec Sprinter. Your van has a far bigger (25-30%) dpf compared to the bluetec Sprinters, therefore the values and data can be completely different.
 

painej

New member
First... Why was the pressure sensor changed?

Based on what you stated/described so far, I think you do have a dpf that is lived its life and it needs to be replaced. You took it to a shop (you did not clearly state why) where the good guys replaced the pressure difference sensor in trying to see if that is the fix for the problem. What more likely happened is, the good guys did reset the ash value to 0 after replacing the pressure difference sensor and now you have a situation where the ECU has a 0 value for the ash level that does not correspond to the pressure difference that the ECU is reading, throwing a red flag at you with the code 2626. The ash value is calculated in the total fill level of the DPF and in this case that I describe the total fill level/value does not correspond/match to the pressure difference read by the ECU. Does that make sence?... Ask the good guys to explain you what they did exactly after they changed the sensor. Did they do any teach-in or initialization?

I think (not sure 100%) the way the ash level/value is calculated is per number of regenerations. One regeneration has a fix value or amount of ash figured and that value is multiply by how many regenerations have occurred. If one regeneration creates .01 grams of ash, .01 x 100 (as an example) = 1 gram of ash. I think that is how the ash level/value is calculated, since the dpf itself does not have anything that can distinguish between soot and ash in its system. Make sense?

Now... When the value is set to 0 but the dpf is still old, pressure difference vs total fill level, will throw everything out of the specified/programmed parameters.

One more thing, if someone here gives you any data to you for comparison, it must be from a non-bluetec Sprinter. Your van has a far bigger (25-30%) dpf compared to the bluetec Sprinters, therefore the values and data can be completely different.
Thanks for the detailed response. The pressure sensor was replaced because it was giving unreasonable pressure differential values a couple of months ago (I don't recall the DTC). Given that there are 300k miles on the van, I agree that the reported ash value (0!) is unrealistic, and that the mechanic probably reset that using their instrument. I don't believe they have the capability of teaching-in at their shop, so as you say, the ECU could be confused and that could be the source of the P2626 code.

If the DPF pressure differentials of 100 hPa or less are believable, that would seem to indicate that the DPF isn't clogged despite its mileage. I was under the impression that the ECU used that value to determine whether the DPF is clogged, and IF (big if) the values are correct, it would seem there's not much restriction there. The exhaust back pressure values don't seem inordinately high either, so perhaps the inability of the shop to do a proper teach-in could be the source. There's an independent Mercedes shop in the central Texas area I could visit for further diagnosis and teaching in, I suppose.
 

manwithgun

Active member
The Autel AP200 can be had for under $70 and adapt new and used DPFs and perform active/passive regens. Search this site in the "Scanner" section for more specific details. Not the best, but certainly the most affordable and extremely capable little unit. It's just slow and a bit clunky to operate. If going this route, be sure to select "Benz Sprinter" for your free vehicle file to cover your Dodge Sprinter.
 

Kajtek1

2015 long/tall limo RV 2.1l
The discussion if Autel HT200 is just name change for Walmart distribution is still with the jury, but it sells for $49
 

painej

New member
The Autel AP200 can be had for around $70 and adapt new and used DPFs and perform active/passive regens. Search this site in the "Scanner" section for more specific details.
Thanks! It looks like the one I have (Autel MK808BT) does that too. With 300k miles, though, perhaps it's time to just bite the bullet and change out the DPF. Although I've used the recommended low-ash oils throughout it's life, I'm sure the ash levels are pretty high by now. There are some interesting articles on reduction in soot capacity (and thus increase in regeneration frequency) with increasing ash levels, including this one:
https://dieselnet.com/tech/dpf_ash.php#:~:text=In other words, the amount,with the minority being soot that suggest that no matter how careful you are, you're gonna accumulate a lot of ash over time. If that's the best route, is Europarts the best source?
 
Last edited:

showkey

Well-known member
If you go with the new DPF............the DPF and sensor needs to be “learned or taught in“ at the time of install.
 

painej

New member
Using the Autel MK808, I adapted the ECU to a "used" DPF and was able to clear the P2626 code (so far at least). I'll drive it a while and see if it reappears before replacing the DPF. Thanks to all for your comments and suggestions so far!
 

dakota1992

Sprinter parts specialist
I own a 2007 Dodge Sprinter, 3.0 L V6 (diesel) engine, with just a tad over 300k mi. The CEL is lit. Using the Autel 808, the code is P2626 with no other codes. I just did a test drive while recording exhaust back pressure and differential pressure at differing engine speeds. I've done a pretty extensive online search, but haven't seen much hard information on expected values for an operational DPF. Here mine are, in case anyone would like to weigh in on where these fall relative to a "normal" range:
At idle (770 rpm): exhaust back pressure 1201 hPa (17 psi); DPF differential pressure 12 hPa (0.2 psi).
At 2910 rpm: exhaust back pressure 1750 hPa (25 psi); DPF differential pressure 43 hPa (0.6 psi).
I've seen back pressures as high as 2070 hPa (30 psi) and differential pressures as high as 63 hPa (0.9 psi).

So the question is: do these numbers suggest a clogged DPF? I recently replaced the dpf pressure sensor for unreasonable reported values, and it appears to be functional now. The van runs well, is regularly getting 20-21 mpg, and isn't in limp mode. The ECU is reporting ash content at 0 (seems unrealistic) and soot content at 0.6 g/l.

Thanks in advance for any guidance or links to other discussions I might have missed! I know this is a well-worn general topic among Sprinter owners.
You may want to check the barrow sensor on the very end of the EGR cooler it has 1 plug this may solve your problem... joe
 

painej

New member
After adaptation to the used DPF, the CEL came on again after a little driving. This time . . . it wasn't P2626! There were two codes: both for bad glow plugs (#1 and #2). I checked the resistance of those at the control unit socket, and they were indeed open circuits. There's a glow-plug replacement in my future this weekend!
 

showkey

Well-known member
^^^^^^^^^^^^Glow plug controller too.............
 

Top Bottom