Bucking/Surging Epidemic

[mtsoxfan]

I just had a P139C code, dealer tech spent about 45 minutes laying across motor, reaching the back. Time on a laptop? inside the truck. Was told after 2 hours it needed a differential pressure sensor, to be ordered. Since I mentioned the occasional searching for gears, delayed shift, they said that was related to sensor. 45K miles not sure what any of that is or means...

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[airline tech]

I did have the scanner hooked up at the time, but have tried it hooked up and not hooked up and it's still flashing. Same with forscan. I cleared the DTC log and no codes or DTCs are showing up. Could this be because I unhooked the DPFE sensor and the emissions system needs to run through a full "cycle" to completely reset everything? Asking because the check engine light stayed on in our jeep grand cherokee after replacing a couple emissions system parts and it took x amount of miles until it reset itself even though I had cleared the code.

Yes, its possibly looking for a Drive Cycle to be completed = OBD Readiness, Emissions - As long as you have a noted drivability (fix / better) and it's not faulting - you are good to go.

Once it finalizes its Drive Monitors (and passes) the historical code should clear but if there is still an issue, the code will return.
The main issue with the DPFE is that the symptoms show before it codes (if it even codes)

I would have to dig into (why) the light would flash with key on, as I have never paid much attention to it - you have to note that this may just be due to the fact the engine is not running.
The very most important of a flashing (light) while driving = pull over and stop driving as it implies a major issue has been detected - Its mainly to protect the Cat from damage, if it stays solid then it is detecting an issue but not detrimental to current drive cycle.

 

[Yinzcity]

You said this perfectly. I am a Ford master tech and when I first encountered this condition (not on my own truck) the first tech said it was trans but when I drove it I knew it wasn't transmission related and after talking with another tech he pointed me to the dpfe because years ago on the old rangers f150s ect with egr they had the same issues with the dpfe collecting moisture from the exhaust. After monitoring pids I saw the dpfe pressure erratic I replaced the tube and dpfe reset Kam and problem was solved.

So when my truck started doing the same thing I knew where to go. I just used forscan and my phone since my laptop with fdrs stays in my tool box. Watching the digital readout of the dpfe pressure pid I could see the issue clear as day.

The problem I am seeing here is one people replacing only the sensor and not the tube. It may or may not be part of the problem. If the ports get clogged the it will cause problems. I'm telling you what fixed my truck and several other Rangers I have worked on and I also only use Ford parts, which yes are expensive I paid over $200 for all of my stuff.

Question for you on replacing the tube. (Assuming you mean the metal tube the DPFE sensor connects to and not the rubber hoses between the sensor and the metal tube.) Ford service manual says to remove the EGR valve and cooler to access the tube. Did you have to remove those components or was there enough room to get the tube out by itself? I'd rather not take off the other parts if I don't have to, but sometimes it's easier that way

 

[airline tech]

Question for you on replacing the tube. (Assuming you mean the metal tube the DPFE sensor connects to and not the rubber hoses between the sensor and the metal tube.) Ford service manual says to remove the EGR valve and cooler to access the tube. Did you have to remove those components or was there enough room to get the tube out by itself? I'd rather not take off the other parts if I don't have to, but sometimes it's easier that way

No, the EGR Valve connection is right on top, just (1) bolt (item #3)

The O-Ring (visible) is the EGR Tube connection at the valve

Looks like 3 bracket support bolts, 1 bolt for the EGR Valve connection and 2 bolts for the intake connection.

EGR Connection (O-Ring)
Intake Connection (Gasket-Between the Tube Flange) + O-Ring Between the Intake Flange and Intake Port) - (If needed) (Unsure if that flange connection will be free floating) after disconnection of the tube assembly.

Disconnect both (Rubber Hoses) - Clamps

Remove connector from the ERGT, remove the EGRT and inspect / clean the sensor, the IPC shows a O-Ring seal on the sensor but no Part Number for it, so it most likely will only come with a new sensor. (Inspect - O-Ring for any damage) flattened or cut / nicks etc.
If damaged it may take some digging to find a replacement (equivalent) high heat from a auto-parts store.

 

[Luke Nukem]

@Yinzcity, how's it going? I'm curious about how difficult the tube replacement is and whether it will make a difference for you.

 

[Yinzcity]

@Yinzcity, how's it going? I'm curious about how difficult the tube replacement is and whether it will make a difference for you.

No progress yet, been busy with other projects. Hopefully I'll have some time to work on in this holiday weekend. I did stick my head under the hood and look at it, access to the tube is going to be a bit rough.
Stay tuned...

 

[TJC]

Just ordered 2 sensors from RockAuto (EGR Pressure Feedback (DPFE) Sensor) for $36.90.
2 day shipping arriving tomorrow.

It is a STANDARD MOTOR PRODUCTS Part VP41. Here's the picture they posted. Appears to be a FoMoCo part!

They have them in stock.

 

[runner69]

Looking at the diagram in the link I provided, it looks like they replaced an assembly. I assume the DPFE is part of this assembly. The service manager told me it is part of the EGR system.

The work order states "faulty DPFE" The other day when I test drove the truck I wrote down exactly what the service manager said: "Differential Pressure Feedback Valve, DPFV"

In Ranger33566's post above, I think he identifies the part, but I got the whole assembly in the diagram he posted.

Were you feeling a "miss" in the 1,200-1,500 RPM range at a steady cruse but would go away upon acceleration?

 

[TJC]

Just ordered 2 sensors from RockAuto (EGR Pressure Feedback (DPFE) Sensor) for $36.90.
2 day shipping arriving tomorrow.

It is a STANDARD MOTOR PRODUCTS Part VP41. Here's the picture they posted. Appears to be a FoMoCo part!

They have them in stock.

They arrived this morning. The print has been ground off, but they were sloppy with one and I can read "Malaysia" in the same location as the Ford part. It is identical to the Ford part in every way except for the ground off label. The FoMoCo can not be read, but it is clear that the lettering is much larger and bolder where the Ford logo is on the original. I think it rolls off the same line as the Ford part.

 

[ctechbob]

They arrived this morning. The print has been ground off, but they were sloppy with one and I can read "Malaysia" in the same location as the Ford part. It is identical to the Ford part in every way except for the ground off label. The FoMoCo can not be read, but it is clear that the lettering is much larger and bolder where the Ford logo is on the original. I think it rolls off the same line as the Ford part.

Yup, that's what made me make the original recommendation.

Not saying they won't switch at some point, but for now, stock up at the $18 price and roll with it.

 

[Tim Vogt Sr.]

Were you feeling a "miss" in the 1,200-1,500 RPM range at a steady cruse but would go away upon acceleration?

I sold the truck last year but stay in touch with the owner and the problem has not returned. As I recall, the problem only occurred when I was between accelerating and decelerating- like maybe driving on a road with a slight downgrade where I was maintaining speed but there was no load on the engine. This was easy to make happen when I took the dealer’s service guy for a ride. I don’t recall the RPMs or if the RPM range was specific.

 

[RangerRandy]

I've been watching this thread and others about this bucking/surging issue for a couple of years. I was so thankful that my truck wasn't having that problem...
Well,,, about 6 months ago or so it started a little at a time and slowly got worse. It had gotten really bad in the last few weeks. Beating me to death at slower speeds. So, I purchased this sensor from my local Ford dealer yesterday and installed it. I drove my truck to work and back today and, "Holy Crap", what an improvement! I had forgotten how good this truck runs. I can't believe it was something as simple as that. LOL
Thanks for all the info guys!

 

[TJC]

I am replacing mine tomorrow AM. The bucking is at low RPMs and noticeable. I am only 5'8" tall and I'm going to need my step to get to it. Sill gonna need to lay over the engine a bit,

I miss the days of seeing the ground on both sides of an engine!

 

[cfhgarza]

Ain't no way! I started having some bucking at low speeds about a month. I thought it was bad gas at first but it's been gradually getting worse. I was calling BS on this whole thread but I ordered the Standard brand and just installed it. Only went for a short test drive but I didn't feel any of the bucks or jerks. I'm still skeptical since I was convinced this was transmission problems but I'm hopeful now ??

Here's my factory sensor next to the new guy. Notice the sealant looks yellowed and uneven on the factory unit.

 

[TJC]

I am replacing mine tomorrow AM. The bucking is at low RPMs and noticeable. I am only 5'8" tall and I'm going to need my step to get to it. Sill gonna need to lay over the engine a bit,

I miss the days of seeing the ground on both sides of an engine!

Well, I was a day or two late. Had to wait for it to cool down before replacing the sensor. Completed the task this morning. I tell you, all you tall gentlemen with long arms should thank God! The job was not technically hard, but my step kept slipping back as I leveraged my legs to reach back to the sensor hose clamps with my needle nose pliers. Getting them off was the only hard part, and only due to space and location.

Next time around will be much simpler as I only need to remove the hoses at the sensor.

The truck drives and shifts smoother in the lower gears. The slight bucking is gone, and the light transmission hold when coming to a stop in 1st is gone as well.

I do like how Ford placed a green dot on the hose to insure the installer clocks the hoses correctly.

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