Differential Pressure Sensor Problem

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63693576asd
Posts: 3
Joined: Wed Apr 22, 2015 6:53 am
Vehicle: 2010 Ford Focus mk2.5 TDCI 2.0

Differential Pressure Sensor Problem

Post by 63693576asd » Wed Apr 22, 2015 9:50 am

Hi

My dps seems to be playing up. The dp_dpf PID shows a constant value of 54 kPa. When engine is off or on or at any rpm it still shows the same. This is throwing a DTC to do with the dps and I believe is the cause for my car going into limp mode. Do you think one of the sensors (upstream or downstream of the dpf) could be faulty or the pipes connecting to them could be blocked?

Because i was having issues with the dpf playing up previously. I have had the dpf gutted, and left the sensors intact. I have also had the dpf deleted from the pcm and remapped the car. My final hurdle is this dps sensor which apparently needs to be left intact and cannot be deleted from the pcm. So im trying to diagnose if its faulty and needs replacing or if the pipe is blocked.

I can get it out of limp mode using "reset the diesel particulate filter learned values" service procedure. However, this only lasts one trip until the car is switched off.

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Re: Differential Pressure Sensor Problem

Post by FORScan » Thu Apr 23, 2015 4:51 am

We think in you case you will not be able to get more from a computer diagnostic, so it is a time for visual inspection and land-based tests.

DPS sensor is just a small box with 2 hoses connected:

DPS_focus2_DW.png
DPS_focus2_DW.png (76.31 KiB) Viewed 5391 times
1 - temp sensor
2 - DPF
3 - Hoses from DPF to DPS
4 - DPS

Picture is for Focus Mk2 2.0 TDCi (DW)

So you should check these hoses first of all, they often have a problems. If they are ok (no hole/leak, no contamination), then probablty the problem in in the DPS itself.

63693576asd
Posts: 3
Joined: Wed Apr 22, 2015 6:53 am
Vehicle: 2010 Ford Focus mk2.5 TDCI 2.0

Re: Differential Pressure Sensor Problem

Post by 63693576asd » Fri Apr 24, 2015 5:30 am

Amazingly helpful. Thank you!

Just helps to have a better idea what im dealing with as i have no mechanic experience.

Disconnected the dp sensor and removed it from the car. The upstream pipe has been spirting oil or liquified exhaust vapour (not sure which) into the port on the dp sensor. As a result it is completely coked up with carbon. I have scoured and washed the sensor in detergent. So much crap came out of that little sensor i was amazed. After leaving it to dry thoroughly, i connected it back to the car. The reading has gone from 54kpa to 39kpa. Unsure if the car is cured now but i will see. I will soak the sensor in something stronger to clean the internal chambers of the sensor 100%. Common sense is telling me this should bring it down to a normal kPA reading and car will be fine. Whatever is causing oil to spurt up the upstream pipe is another story entirely i will need to address later.

int0x13
Posts: 19
Joined: Wed Apr 08, 2015 9:57 pm
Vehicle: Ford Focus MK2 2.0L TDCI 136 remapped ECU

Re: Differential Pressure Sensor Problem

Post by int0x13 » Fri Apr 24, 2015 5:53 pm

63693576asd wrote:Amazingly helpful. Thank you!

Just helps to have a better idea what im dealing with as i have no mechanic experience.

Disconnected the dp sensor and removed it from the car. The upstream pipe has been spirting oil or liquified exhaust vapour (not sure which) into the port on the dp sensor. As a result it is completely coked up with carbon. I have scoured and washed the sensor in detergent. So much crap came out of that little sensor i was amazed. After leaving it to dry thoroughly, i connected it back to the car. The reading has gone from 54kpa to 39kpa. Unsure if the car is cured now but i will see. I will soak the sensor in something stronger to clean the internal chambers of the sensor 100%. Common sense is telling me this should bring it down to a normal kPA reading and car will be fine. Whatever is causing oil to spurt up the upstream pipe is another story entirely i will need to address later.
That's interesting. Can i ask you how did you proceed to access to your DPF under the car? You did yourself? because for a person that knows nothing about mechanics, you seem to know a lot! Did you make some pictures of your job and your workshop? Thank you.

63693576asd
Posts: 3
Joined: Wed Apr 22, 2015 6:53 am
Vehicle: 2010 Ford Focus mk2.5 TDCI 2.0

Re: Differential Pressure Sensor Problem

Post by 63693576asd » Sat Apr 25, 2015 11:17 am

No pics unfortunately. Had a local mechanic do the physical work on the dpf. It is illegal where i live to run a vehicle without the emissions controls it came with. Car is euro iv and comes with cDPF, EGR (blanking plate fitted and egr also deleted from pcm), PCV etc. Did have to ask around to find someone willing to do it cash in hand. 3.5 hours labor. Had it jacked up and needed to remove a couple of things temporarily that were obstructing access it. Removed the dpf. Grinded open the dpf and removed the internal element, then welded back together and put it back on facing upwards to make it look inconspicuous. No gaskets used, only silicon sealant. Side effect of dpf restriction removed (apart from not having to worry about regenerations and replacement ever again) is more power, better economy and very noticeable turbo whistle.

PS. Problem appears to be solved. Car is running flawlessly now.

int0x13
Posts: 19
Joined: Wed Apr 08, 2015 9:57 pm
Vehicle: Ford Focus MK2 2.0L TDCI 136 remapped ECU

Re: Differential Pressure Sensor Problem

Post by int0x13 » Sat Apr 25, 2015 1:04 pm

63693576asd wrote:No pics unfortunately. Had a local mechanic do the physical work on the dpf. It is illegal where i live to run a vehicle without the emissions controls it came with. Car is euro iv and comes with cDPF, EGR (blanking plate fitted and egr also deleted from pcm), PCV etc. Did have to ask around to find someone willing to do it cash in hand. 3.5 hours labor. Had it jacked up and needed to remove a couple of things temporarily that were obstructing access it. Removed the dpf. Grinded open the dpf and removed the internal element, then welded back together and put it back on facing upwards to make it look inconspicuous. No gaskets used, only silicon sealant. Side effect of dpf restriction removed (apart from not having to worry about regenerations and replacement ever again) is more power, better economy and very noticeable turbo whistle.

PS. Problem appears to be solved. Car is running flawlessly now.
That is indeed interesting. It's also illegal here, I live in France, where do you live? I have also cDPF car. But i'm currently using a PCM with nPDF because it's a remapped file that is not corresponding to my car. It's a bit problematic because i haven't removed my DPF physically. So if i let this remapped PCM it wont do any regen and my DPF will just die. But i'm just testing this remapped file and do some power bench to check the torque/power. After my testings i will switch to another remapped file with cDPF support. The really interesting thing about my experiment is that i still have the DP_DPF PID sensor accessible and readable with my nDPF PCM. So even if you use a PCM from a nDPF car, it still contains the code to read the DPF sensors. And i guess it would trigger a DTC if your pressure will go above the limit value (i think something like 60-70kPA). So in fact a PCM marked a nDPF has not the code to make the full DPF handling, (the Regenerations and so on), but it has enough code to read the sensors.
In your case, im pretty sure that your DPF OFF remapped file is not well done and properly done. If it would be, you would see any DTC coming from the sensors AKA DPS. You should try to contact a better tuner/remapper because i'm pretty sure you can solve this issue by better remapping. I think for the moment you solved your issue, but it will come gain if you dont properly remap your PCM.

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