Is this pressure sensor missing a pipe?

[REH17]

Hi all. Got a replacement dpf pressure sensor today.. and before I code it ( I understand its one chance to code it / adapt it and it cant be re adapted) I want to make sure Im not missing a pipe... It doesnt look right. Found a diagram online that suggests I should have 2 pipes off the sensor.. one of mine is cut off / missing. Could this be the source of all my regular active regens.  

 

The diagrams below may not be my actual car but surely the idea is correct.. one pipe pre and one post dpf to monitor pressure.... 

 

Skoda Octavia Scout 2011 cr140 2.0tdi

 

Answers hugely appreciated as I wanted it fitted before the weekend. Thanks. 

[Anddenton]

I am amazed you haven't got a warning light for that, should definitely be connected, one pipe pre dpf  and one post to monitor the pressure difference, hence why it's called the differential pressure sensor.

[REH17]

Just as I thought.. no warnings.. no fault codes... any idea on a part number for the said missing pipe please? 

[Anddenton]

Are you sure it's not come away and is hanging somewhere down the back of the engine? 

Sorry, no idea of part no. Will need someone with the parts catalogue for that but I got a warning light when my pressure sensor failed at 150k miles in my pd scout and I can't believe that pipe being missing doesn't give measurements that are so out of scope that a fault scenario isn't triggered.

[REH17]

Car runs fine. But regens every 100 miles... obviously im loosing fuel every time it does so... 3 or 4 regens per tank soon damages the range:/ cant see any pipes hanging but will have a look tomorrow

[REH17]

I get differences on actual and calcuated soot.  . This app might not be 100% reliable but its a good indication of whats happening.  I know dpf isnt blocked and egr is fine as had them tested... regens produce very little.. usually just blue smoke burning fuel.. 

[SuperbTWM]

To me it looks like its the low pressure side that is not connected so comparing the high pressure side to atmosphere the car will be getting a high reading thinking the DPF is blocked all the time. That is probably why its not showing an EML.

 

If the low pressure was connected and the high side open to atmosphere the reading would be negative which would probably ring alarm bells with the ECU.

 

if not then who knows what has gone on but it needs sorting out before your oil is completely saturated with diesel.

Edited 1 November, 2017 by SuperbTWM

[REH17]

So in my photo.. should the pipe go into the top of the dpf where the bolt / screw thingy is on top.....

[Anddenton]

That is a ridiculous amount of regens, even my 170k miles pd scout doesn't Regen anything like that amount. I'd guess it's all down to that missing pipe.

How the he'll it gets soot mass measurements with that pipe missing I don't know but one side of the sensor will be presumably giving atmospheric pressure which will mean measurements are wildly out of kilter so soot level could be very different to what the ecu expects, therefore the ott regens. 

[SuperbTWM]

Does the new sensor have any markings as to which is the high and low pressure side of it. You really need to determine this before you go any further because you don't know if the pipe that is connected at the moment is even in the right place as somebody may have been playing about with it.

 

Then you need to make sure the hose from before the DPF goes to the high side of the sensor and the after DPF pipe goes to the low

[Anddenton]

9 minutes ago, REH17 said:

So in my photo.. should the pipe go into the top of the dpf where the bolt / screw thingy is on top.....

Looking at your earlier diagram it's difficult to be sure but it looks like you're correct.

 

Edit. Scrub that the two diagrams seem contradictory to me?

Edited 1 November, 2017 by Anddenton

[REH17]

I will have to have a look tomorrow... but if anyone has a cr140 tdi engine and wouldnt mind sharing a photo of the same bit so I know what it should be like....

 

Also any workshop manual or accurate diagrams would be most useful. 

[REH17]

3 minutes ago, Anddenton said:

Looking at your earlier diagram it's difficult to be sure but it looks like you're correct.

 

Edit. Scrub that the two diagrams seem contradictory to me?

Yes I got 2 just to see if the dpf had an in and out pipe for the sensor... the 2nd diagram seems to match my engine

[Anddenton]

4 minutes ago, REH17 said:

Yes I got 2 just to see if the dpf had an in and out pipe for the sensor... the 2nd diagram seems to match my engine

Yeah second diagram seems to suggest it should connect to that bolt/screw 

[LightRain]

9 hours ago, Anddenton said:

Edit. Scrub that the two diagrams seem contradictory to me?

I think that's because the sensors are mounted in different orientations in those diagrams.

 

If I were OP I'd be getting into that engine bay and looking for the other part of that open line, if that results in nothing, then I'd be tracing backwards from the DPF/exhaust looking for anything amiss. I'm assuming you replaced the sensor yourself? However if you got a garage to do it, I'd be on to them like a ferret for not completing the job.

 

Anyway, if this pipe has always been missing there's a chance the old sensor was fine, if so maybe you can get a refund on the part.

[langers2k]

I'll check my CR140 when I go out today but I thought only one end of the sensor was connected on CR engines?

 

Your picture certainly seems to match this diagram for CFHC, CLCA, CLCB engines:

[LightRain]

39 minutes ago, langers2k said:

I'll check my CR140 when I go out today but I thought only one end of the sensor was connected on CR engines?

Your picture certainly seems to match this diagram for CFHC, CLCA, CLCB engines:

 

Well blow me down, you might be right.

 

http://www.realoem.me/Skoda/CZ/OCT/2011/663/R/2/253/253063#10

https://skoda.7zap.com/en/cz/octavia/oct/2011-663/2/253-253063/#1

Edited 2 November, 2017 by LightRain

[langers2k]

Just checked my car, as expected it's identical to the OP's and only has one pipe connected.

 

@REH17 - are you able to log values whilst you drive using your OBD dongle? I should have some I made with VCDS a while back. How frequent are your regen's and have you had 'the fix' done? What made you think the pressure sensor was at fault and needed replacing?

 

[REH17]

Fix was done. Remapped. Unremaped then put back to pre update.  I get 100 miles ish between regens. On the va dpf app i get a minus value sometimes once a regen complete on the calculated bit...

 

It only measures 20g ish of soot then goes to 100%... just seems too frequent.. thought by changing sensor could eliminate it.

 

So as far as we know my pipes on the sensor are correct...? 

[REH17]

6 hours ago, LightRain said:

I think that's because the sensors are mounted in different orientations in those diagrams.

 

If I were OP I'd be getting into that engine bay and looking for the other part of that open line, if that results in nothing, then I'd be tracing backwards from the DPF/exhaust looking for anything amiss. I'm assuming you replaced the sensor yourself? However if you got a garage to do it, I'd be on to them like a ferret for not completing the job.

 

Anyway, if this pipe has always been missing there's a chance the old sensor was fine, if so maybe you can get a refund on the part.

I have someone local with vcds to do the adaptation on the new part... just wanted to make sure I didnt have bits missing before I wasted 60 quid and ruined a new sensor... I understand they cant be readapted once done...

[langers2k]

Your pipes match my pipes so yes, they look correct

 

In terms of soot content, there are a few stages:

- 0 to 18g, passive regeneration, this occurs 'naturally' if the engine is warm enough.

- 18 to 24g, active regeneration, the ECU will increase the exhaust gas temperature to burn the soot off.

- 24 to 40g, DPF light illuminates, drive as per the manual instructs.

- 40 to 45g, DPF, ECU, glow plug lights illuminate, needs a service regeneration from a dealer or VCDS.

- 45g or more, DPF replacement.

 

I'm not sure what the percentage value the app is giving you actually is as I don't recall a % for soot loading from VCDS. At a guess, it's probably the soot mass measured as a percentage of 18g (ish).

 

What is your measured and calculated soot mass just before and after a regeneration?

 

Assuming I've understood what you've said so far, everything appears to be working normally but it's making a lot of soot in 100 miles to go from 0 to 18g. I don't think changing the pressure sensor will change this...

[REH17]

I just dont remember it ever doing active regens this often and now I notice them due to the smoke from the back... if I stop at roundabouts etc mid regen once taking off again the smoke is noticeable... I remember it passively regening before.. fans on Higher revs etc but never any smoke.. Im just guessing that the sensor is damaged... as I got a minus value after a regen... and the calculated and measured values are way different... plus is seems to jump from 60 % to 80% rather quickly... so I naturally assumed faulty sensor.. mis reading.. causing frequent active regens... 

 

If anyone has vcds and knows how to log live data Id welcome them to help me.. I also have the torque app but unsure how to read the live data properly and I dont think it measures pressure through dpf on my car...

[REH17]

Ok so a few screenshots from tonight.

 

Drove up motorway in 5th until it reached 100%.. circa 20g soot measured.

 

Regen happened.. few mins and it finished..  but I get a minus value on Actual and 5g ish on calculated. It never goes lower than 20 odd %and circa 5g... 

 

Surely this is a sensor fault... pretty sure we have established the small pipe on sensor is correct

 

Thoughts? 

[SuperbTWM]

Maybe a new sensor was fitted without adaptation hence the zero error?

[LightRain]

Didn't you replace the sensor? It isn't impossible but it is unlikely that a new sensor is dead out of the box.

Did the old sensor show the same anomalies?

Did you run the necessary adaptations?