Bucking/Surging Epidemic

[RangerBill]

You can monitor and test the system as I previously posted and plan of hooking up Forscan for normal readings on the DPFE sensor voltage.
That voltage is the key to this issue.

Since the EGR system runs in a closed loop, are you sure that you will see a problem with the sensor feedback voltage if the sensor is bad? If the feedback voltage was off from the expected value, I would surmise the PCM would issue a DTC. It seems to me that the feedback is low with a bad sensor and the PCM responds by increasing the EGR flow, causing too much exhaust gasses going back to the intake, causing the engine missing. Just my thoughts.

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[airline tech]

Since the EGR system runs in a closed loop, are you sure that you will see a problem with the sensor feedback voltage if the sensor is bad? If the feedback voltage was off from the expected value, I would surmise the PCM would issue a DTC. It seems to me that the feedback is low with a bad sensor and the PCM responds by increasing the EGR flow, causing too much exhaust gasses going back to the intake, causing the engine missing. Just my thoughts.

The voltage on the sensor should increase with flow - and if not sensing flow correctly- EGR open when it should not be open or staying closed when it should be open.

 

[RangerBill]

The voltage on the sensor should increase with flow - and if not sensing flow correctly- EGR open when it should not be open or staying closed when it should be open.

But apparently, the PCM increases the flow too much, and is able to achieve a correct feedback voltage and therefore throws no code. But this causes too high of EGR gasses and a missing engine. My point is that measuring the feedback voltage with Forscan may not show a problem.

 

[airline tech]

But apparently, the PCM increases the flow too much, and is able to achieve a correct feedback voltage and therefore throws no code. But this causes too high of EGR gasses and a missing engine. My point is that measuring the feedback voltage with Forscan may not show a problem.

Although true, with the DPFE voltage PID, it may or may not show a problem.
But being that a Torque Convertor and Transmission Relearns are being performed by dealers, and still have the same issues, and then some owners are replacing the DPFE, and problem goes away.
I cannot see a dealer replacing a Torque Convertor, for a EGR system related code.
There are other sensors that tie into the EGR system to control the EGR valve position, but by this thread and other online sites, it appears that the DPFE sensor is a known failure part and has been for years. This is the main reason I am wanting to focus on that specific part of the system without troubleshooting the whole system (No-Code) diagnostics.

So, we need to re-shift focus away from the transmission and focus on the EGR system, with it being that owners on here are reporting a positive fix with the DPFE, I would focus on what the voltage reading is for it.

This is why, I would like to see some checks before replacing it, vs just throw a part at it.
To get a confirmed - out of spec voltage reading that is not generating a code.
I have not had time yet to hook up and provide some normal readings for comparison checking with all other members on this forum.

Being that the Ford manuals are vague with testing DPFE and gives you a wide range of specs this is why a posting of a failed sensor value (without) a fault code vs a working normally system to compare values, would be helpful to owners who are experiencing this drivability issue.
Side by Side Comparision.

Here are some system descriptions.
From Online source:
Note any ref to vacuum control to EGR is not related to the Ranger, ours is electronically controlled.

Taking a closer look at how Ford does EGR | Vehicle Service Pros

and

Ford EGR-ESM Diagnosis (underhoodservice.com)

From the service manuals - PDF's

 

[MrBusses]

I did the pcm reprogram on mine today. And after a panic attack when the program failed and blanked the pcm with the help of my Foreman got it programmed and seems to be running better.

 

[Wytchdctr]

I did the pcm reprogram on mine today. And after a panic attack when the program failed and blanked the pcm with the help of my Foreman got it programmed and seems to be running better.

That is one hell of a heart sinking / shit feeling. I didn't brick mine but on a flash I fired it up and was looking at that freaking check engine light. Read the code and the crank angle sensor needed to be reprogrammed. Also the tuner box pulled codes for a transfer case (I don't have one so.... yeah.. normal code reader didn't see those) After a lot of brand new made up curse words I figured out how to recover without the dealer.

But yeah.. that sucks to see a flash go really wrong.

/// General question

On the part causing this problem.. any tips on when to shotgun it to get ahead of the issue? This almost feels like replacing spark plug type maintenance. Might do it at 50 when I yank the plugs.

 

[Msfitoy]

I had forgotten how smooth the truck was many many miles ago before the slow onset of bucking/surging combined with a failing/failed transmission...after the transmission replacement, it was still hard to modulate slow driving...now everything is smooth at low and higher speeds...very enjoyable like I remembered when she was new...the EGR sensor is original, no code was ever detected by Ford techs and no PCM reprogramming recall was ever performed...only the DPFE sensor was replaced...

 

[navsnipe]

I did the pcm reprogram on mine today. And after a panic attack when the program failed and blanked the pcm with the help of my Foreman got it programmed and seems to be running better.

I'm curious what PCM reprogram you speak of. What does it correct or address? I had my 2020 at the dealers two weeks ago for a couple of driveability issues. I asked about firmware updates and I got no for the answer. Somehow my truck is running better though.

 

[MrBusses]

I'm curious what PCM reprogram you speak of. What does it correct or address? I had my 2020 at the dealers two weeks ago for a couple of driveability issues. I asked about firmware updates and I got no for the answer. Somehow my truck is running better though.

Only applies to 19s it looks like.

 

[ppfd]

Yes, the thousandth post on a similar issue everybody describes differently.
Truck has from the day I owned it, vibrated, shook, shuddered, feels like it has a miss. Pretty much what everybody is describing and sounds like transmission issues and or drive line as well.
Over the last 2 weeks it seems to be getting worse as I have to get up to 30-40 MPH to "clear it out". Prior to this the truck did all of the above in low speed city driving.

So my questions are more direct here: Do I just describe whats going on to the dealer? Are there TSBs for this? Can I ask for anything specific as far as the transmission and or drive line?

Apologies for asking the same thing again!
And thank You!

 

[Msfitoy]

Yes, the thousandth post on a similar issue everybody describes differently.
Truck has from the day I owned it, vibrated, shook, shuddered, feels like it has a miss. Pretty much what everybody is describing and sounds like transmission issues and or drive line as well.
Over the last 2 weeks it seems to be getting worse as I have to get up to 30-40 MPH to "clear it out". Prior to this the truck did all of the above in low speed city driving.

So my questions are more direct here: Do I just describe whats going on to the dealer? Are there TSBs for this? Can I ask for anything specific as far as the transmission and or drive line?

Apologies for asking the same thing again!
And thank You!

You're describing the same symptoms I "used" to have...replace your DFPE valve...

https://www.ranger5g.com/forum/threads/bucking-surging-epidemic.14581/post-573946

 

[airline tech]

DPFE Sensor,

Explanation of possible reason for - No-Code, drivability issues
Buck/Surge/Stumble/Ping/Misfire Etc

Now there are other sensors that tie into the control of the EGR valve, and rather than troubleshoot the other sensors, lets focus on a very common failure part - The DPFE sensor.

Being that this is a No-Code issue, its highly likely a dealer will just send you back out the door and say No-Code, No-Problem.

I would rather not have anyone just replace the part and say it fixed it, we need to find what the voltage PID for the failing DPFE is showing on a scan tool or Forscan.
Next week I plan on posting what a normal EGR system reading should be, including the DPFE Voltage PID.

If this part is fixing the issues, then the voltage PID for the DPFE will be different between the old, failed part and the new part.
How much of a difference - IDK, but that is why I am asking, before you change it, get some data readings so we can see a possible commonality, between the failed sensors.

I think what is happening is that the sensor is failing and giving bad / false flow information.
This is due to the moisture contamination. that comes naturally from the hot exhaust gasses flowing through the sensor.
Now in this instance for (No-Code) the sensor has not completely failed. (Flatlined) dead.
So, it is less sensitive to flow and not reading a correct Differential Pressure between both of the hoses.
If this incorrect reading was sensing a lower flow than actual flow, then the PCM will command the EGR Valve to open farther than it needs to be. (Feedback Reading to the PCM causes this)
Thus, leaning out the fuel mixture, generating a lean misfire and improper fuel delivery.
This is when you notice all the issues of Buck/Surge/Stumble/Ping Etc.

The Differential Pressure comes from readings from both sides of the hoses that are attached to it, there is an Orifice Tube, between the 2-pressure sense hoses, within the EGR Tubing
Hi and Low Side -Pressure or (Upstream and Downstream) Pressure
The differential pressure between the (2) is converted to a voltage signal and sent to the PCM, which takes all of the system sensor inputs and then commands the EGR to open and close based on engine parameters and load.

The Voltage PID reading = that pressure difference, with EGR Flow.

From what I can tell, unless the DPFE completely fails, it will not trip a code.
You may try cleaning the sensor, blow it out with air or clean with a electronic cleaner, such as MAF sensor cleaner.
Do not use Brake Clean or Carb Cleaner

 

[RangerBill]

DPFE Sensor,

If this part is fixing the issues, then the voltage PID for the DPFE will be different between the old, failed part and the new part.

In a closed loop system, not necessarily. If the sensor feedback is low, the PCM will just increase the signal to the EGR valve to increase the EGR gas flow, until the sensor produces the correct feedback voltage. The closed loop may be satisfied, but the engine is missing from too much EGR gas flow. I am just surmising this, but I am familiar with closed loop controls in electric motor drives. You can have a speed sensor go bad (tachometer feedback) and the drive merely adjusts to a wrong speed based on wrong feedback, and the drive is perfectly happy running the motor at the wrong speed.

I say all this based on the PCM not producing a DTC code, so the PCM seems to be happy with the EGR closed loop control. I could be wrong though. It would be interesting to see if the DPFE voltage is different on a working sensor and a malfunctioning one, but I am not sure a difference will be noticeable, unless the sensor is completely bad. That is what makes troubleshooting closed loop systems difficult sometimes.

 

[ppfd]

You're describing the same symptoms I "used" to have...replace your DFPE valve...

https://www.ranger5g.com/forum/threads/bucking-surging-epidemic.14581/post-573946

Are those ford part numbers?
I am so over this truck, Ill just spend 80 bucks instead of the hassle of making multiple trips to the dealer only to hear, “we can’t find anything wrong.“

Thanks!

 

[Msfitoy]

Are those ford part numbers?
I am so over this truck, Ill just spend 80 bucks instead of the hassle of making multiple trips to the dealer only to hear, “we can’t find anything wrong.“

Thanks!

Yes, part numbers...all I can tell you is that my butt meter is saying all the stuttering/bucking/hesitation/lumpy behavior has vanished...get the part and fix it yourself...F-Ford...

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