Bucking/Surging Epidemic

[Racket]

It is likely that nothing 'breaks'. What I think happens is that the moisture gets into the sensor substrate and either causes the signal to change or causes some bond to be weakened that changes the signal output.

Between the wild price swings on the replacement part and the frequency of having to replace it I would think there is some way to improve the design. A sealed diaphragm over the sensor to isolate it or some way to neutralize whatever is ruining it. Maybe just the mounting orientation?

Rockauto suggested the EGR pressure sensor too (see screen grab below), but I don't see anyone chasing down that component being a part of the issue. Or the EGR. I'd be curious how all these connect and whether a fix is somewhere else... Problem being it's a no-no fooling with emissions systems even if you improve them.

The change out has made a big difference for me even after I thought it hadn't gotten so bad.

This thread should be a sticky.

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[notsolinear]

I know that the water/moisture damage has been floated as a theory, but I don’t think we have any proof yet of that being the cause, right? So far everyone I’ve seen who has performed the service manual test on the sensors they’ve replaced have found them to pass the test. That leaves a little doubt in my mind as to what’s going on.

 

[Racket]

Rock Auto just got the generic sensor back in stock, a third of the OEM cost and while I've learned some aftermarket parts are garbage this isn't some potentially life threatening component (like a hall effect sensor for a Chrysler crapping out in heavy highway traffic) someone here claimed it's the same as the Ford part without markings so we'll see. Maybe I should have gotten two at under $20 each.

 

[Luke Nukem]

Any suggestions for how to proceed? Bought the assembly with hoses from Levittown, installation went smoothly. Anyone else had one dead-on-arrival? Is there anything I can check to diagnose it as faulty to rule out some other issue?

I'm curious if you tried replacing yours again. I replaced mine in February, and I am now starting to get the same symptoms I had before.

 

[notsolinear]

I'm curious if you tried replacing yours again. I replaced mine in February, and I am now starting to get the same symptoms I had before.

I did, shortly after that post. First test drive after install seemed better than usual, but since then I've had to admit it's really no better than before either replacement. That plus the bench-test results not showing any clear issue leaves me at a loss for what to do next: Maybe it's an issue in the harness and not the sensor? Maybe it's some other related component? Maybe it's not related at all, just manifests exactly like this issue has for dozens of other people...

 

[ctechbob]

Rock Auto just got the generic sensor back in stock, a third of the OEM cost and while I've learned some aftermarket parts are garbage this isn't some potentially life threatening component (like a hall effect sensor for a Chrysler crapping out in heavy highway traffic) someone here claimed it's the same as the Ford part without markings so we'll see. Maybe I should have gotten two at under $20 each.

That someone is me. Of all 3 that I've ordered all have been OEM parts with the markings scrubbed off. You can tell since they usually leave a bit of gold dust behind. Maybe at some point it will be a completely aftermarket part, but at least for the moment, they're the same.

 

[MrBusses]

Thought I would chime in on this thread as I was having the same issue with my ranger. Around the 7th/8th gear 35-45mph under light throttle just maintaining speed I would experience the bucking/jerking that everyone seems to have. I used a combination of forscan on my phone and FDRS and while driving I noticed DPFE would read negative then switch positive then back negative with egr open anywhere from 10-75%. Also Num)misfire would record misfire counts. Per the PCED reference values i should be reading around 0.09psi at 55mph not -0.5psi

I replaced both my egr tube and dpfe and it solved my issue. I did the tube just incase there was blockage causing a restriction but after removing it and cutting it open I could have gotten away with out.

If you look at the screen shot from FDRS you can see how the DPFE reading is switching negative to positive while egr is open. and the picture of the dpfe you can see moisture that I shook out of it. After replacing the tube and sensor my readings went back to normal and EGR is only opening to about 15% now.

 

[airline tech]

Thought I would chime in on this thread as I was having the same issue with my ranger. Around the 7th/8th gear 35-45mph under light throttle just maintaining speed I would experience the bucking/jerking that everyone seems to have. I used a combination of forscan on my phone and FDRS and while driving I noticed DPFE would read negative then switch positive then back negative with egr open anywhere from 10-75%. Also Num)misfire would record misfire counts. Per the PCED reference values i should be reading around 0.09psi at 55mph not -0.5psi

I replaced both my egr tube and dpfe and it solved my issue. I did the tube just incase there was blockage causing a restriction but after removing it and cutting it open I could have gotten away with out.

If you look at the screen shot from FDRS you can see how the DPFE reading is switching negative to positive while egr is open. and the picture of the dpfe you can see moisture that I shook out of it. After replacing the tube and sensor my readings went back to normal and EGR is only opening to about 15% now.

Just curious, when you cut the tube open, is there a (Filter- Orifice Tube) like the AC type
I wonder if the moisture droplets flowing in the tube is causing the actual issue.
Mainly the junction point (branch) between the upstream and downstream.
Water droplets creating a temp blockage in the small (Upstream) branch of the tube until it is pushed out from the exhaust pressure.

To clarify this for those to understand what is happening.
The (- negative pressure) readings are (Intake Manifold) (Downstream) Readings
The (+ positive pressure) readings are the (EGR Flow) (Upstream) Readings

The DPFE Sensor is installed inline (with the Orifice Tube)

Note:
The DPFE Sensor
The Right Connection (smaller diameter) hose = Downstream Pressure (Intake)
The Left Connection (larger diameter) hose = Upstream Pressure (EGR Flow)

I am thinking the water droplets may be creating a pressure offset in the small branch nipple on the tube itself, this is in addition to the moisture collecting in the sensor itself creating faulty readings. (while driving)

This will only code (P139C) when the system is in self-test mode (Once per driving cycle)
If it passes the self-test (no code will be generated)
So, for this sensor, while driving - It does not see the switching back and forth.
You have the symptoms with no codes.

 

[MrBusses]

Just curious, when you cut the tube open, is there a (Filter- Orifice Tube) like the AC type
I wonder if the moisture droplets flowing in the tube is causing the actual issue.
Mainly the junction point (branch) between the upstream and downstream.
Water droplets creating a temp blockage in the small (Upstream) branch of the tube until it is pushed out from the exhaust pressure.

To clarify this for those to understand what is happening.
The (- negative pressure) readings are (Intake Manifold) (Downstream) Readings
The (+ positive pressure) readings are the (EGR Flow) (Upstream) Readings

The DPFE Sensor is installed inline (with the Orifice Tube)

Note:
The DPFE Sensor
The Right Connection (smaller diameter) hose = Downstream Pressure (Intake)
The Left Connection (larger diameter) hose = Upstream Pressure (EGR Flow)

I am thinking the water droplets may be creating a pressure offset in the small branch nipple on the tube itself, this is in addition to the moisture collecting in the sensor itself creating faulty readings. (while driving)

This will only code (P139C) when the system is in self-test mode (Once per driving cycle)
If it passes the self-test (no code will be generated)
So, for this sensor, while driving - It does not see the switching back and forth.
You have the symptoms with no codes.

No There is nothing in the tube. There was no moisture in the tube or the hoses only up in the sensor itself.

 

[airline tech]

No There is nothing in the tube. There was no moisture in the tube or the hoses only up in the sensor itself.

OK, Thanks

Just curious if the Pinpoint Test (Bench Test) would provide a (test fail) or (test pass) on the DPFE Sensor?
or if it only shows itself during a drivability test

I am just looking at easy solutions for those who have changed the DPFE and still have issues and do not have the capability of a drive (live data) monitor testing.
It was a (Good Catch) seeing the sensor data drop and switch so with the tube clogging ruled out.

With only focusing on the DPFE sensor operation and its tie into the EGR system.
Other possibles would be a leaking seal / gasket on either end of the ridged tube or DPFE Hose connections or from the threads of the EGR Temp Sensor (EGRT12)
If this is a small leak, it may not affect Idle (noticeable) but could cause an Askew of the sensor data.

 

[MrBusses]

OK, Thanks

Just curious if the Pinpoint Test (Bench Test) would provide a (test fail) or (test pass) on the DPFE Sensor?
or if it only shows itself during a drivability test

I am just looking at easy solutions for those who have changed the DPFE and still have issues and do not have the capability of a drive (live data) monitor testing.
It was a (Good Catch) seeing the sensor data drop and switch so with the tube clogging ruled out.

With only focusing on the DPFE sensor operation and its tie into the EGR system.
Other possibles would be a leaking seal / gasket on either end of the ridged tube or DPFE Hose connections or from the threads of the EGR Temp Sensor (EGRT12)
If this is a small leak, it may not affect Idle (noticeable) but could cause an Askew of the sensor data.

Only way I know how to test the sensor is with a vacuum pump and monitor the pid. if it moves steady its not the sensor. In reality without connecting to a scan tool and monitoring pids you are just throwing darts in the dark. DPFE might be only part of the problem, it could be a restriction in the tube could be the EGRT sensor on the tube, maybe the valve its self. Might not be related to the EGR at all. There is a TSB to reprogram the PCM for a similar condition. I did this when I first got my truck and it fixed it for about a year. Then about a month ago I started having the bucking at higher speed and when warm.

 

[airline tech]

Only way I know how to test the sensor is with a vacuum pump and monitor the pid. if it moves steady its not the sensor. In reality without connecting to a scan tool and monitoring pids you are just throwing darts in the dark. DPFE might be only part of the problem, it could be a restriction in the tube could be the EGRT sensor on the tube, maybe the valve its self. Might not be related to the EGR at all. There is a TSB to reprogram the PCM for a similar condition. I did this when I first got my truck and it fixed it for about a year. Then about a month ago I started having the bucking at higher speed and when warm.

Good Point - Here for those who have used the Vacuum Test method, the sensor reading should be steady and not fluctuate.
So, apply the vacuum slowly and monitor for a steady increase in voltage (incrementing) the amount of vacuum slowly then stop (watching) the voltage hold steady or jump (if jumping) then the sensor is failing.
I truly do not know how accurate a Bench Test would be on these anyways unless it is way off.
As you are missing a main factor (heat) across the sensor.

As, Mr. Busses stated the only way to really test is Live Data Monitor and the most important of that Live Data is the EGR Valve open position. (yes, EGR Temp ties into it as well) but for this specific thread and EGR Flow issues / Buck Surge it's the Open Position of the EGR valve that is important.

 

[MrBusses]

For those who are replacing the just the DPFE and still having the issue you should replace the EGR tube as well as the hoses to the DPFE. Another thing to take into consideration is that this concern might be trans related, but like I said you need a scan tool that can read the data stream and you need to know how to interpret that info otherwise its all guess work and money potentially wasted.

 

[notsolinear]

I finally bought an adapter to use with FORScan: Scanned through the list of PIDs and can’t see any for the DPF/DPFE sensor. Am I doing it wrong or does FORScan not support those PIDs?

 

[airline tech]

I finally bought an adapter to use with FORScan: Scanned through the list of PIDs and can’t see any for the DPF/DPFE sensor. Am I doing it wrong or does FORScan not support those PIDs?

I got out of automotive before Scan Tools were a norm and required for in depth troubleshooting.
So, I am not 100% sure on this, but I believe that scan tool capability can vary by what PID's they are able to display.

For generic data - across all makes / models - if it has Live Data Pids , these will display.
For - Ford Specific (Live Data) such as DPFE - This is Enhanced Data Pids
These Pids may or may not be able to display on the scan tool and requires them to be unlocked for viewing by the scan tool software

So, with FDRS's - Fords Software - all is unlocked without any blockage of data

Below is my GUESS on why 3rd party scan tools differ in display of Live Data

3rd party (aftermarket) scan tools require permission from Ford to allow display of that enhanced data. (possibly have to pay a license fee)

The higher end 3rd party scan tools appear to always have enhanced data pids (such as Snap-On) as they are most used in a shop environment outside of the dealer, however these are $10,000 tools and are paid for by the customers over time for this expensive investment

In September of 2023, I noted an update for Ford Software on my Autel MS906TS scan tool, I downloaded and updated the tool, I now have the Ford Enhanced live data pids, previously to that date I did not have it.
Now the specifics on how I got it - IDK, Ford gave them permission free or paid or a specific length of time elapsed for it to be allowed and it became free source.

So, at this time and current Forscan version, I do not believe that the DPFE data is available, it may be at a later update. IDK as I am not 100% sure how that (legal) side of the data permission works.
The data is there for viewing but it takes the proper software (authorized) to view it.

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