Transmission starts shifting roughly, then issues go away.

[Tim H.]

I still fail to understand what the DPFE's connection to the transmission...it causes stumbles and general drivability issues that might seem like transmission but it's NOT connected or drives any function of the transmission...correct me if I'm wrong?

It caused an engine performance issue which appeared like it was a trans shifting issue.

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[Msfitoy]

It caused an engine performance issue which appeared like it was a trans shifting issue.

That's what I keep saying...DPFE valve has nothing to do with the transmission...but it keeps being conflate with real transmissions issues...

 

[Tim H.]

That's what I keep saying...DPFE valve has nothing to do with the transmission...but it keeps being conflate with real transmissions issues...

A faulty DPFE solenoid causes the fuel mixture to be lean, resulting in a lean misfire or hesitation especially during trans shifts.

 

[airline tech]

Its more about the sensor that sees the pressure changes in the Intake Manifold when the EGR Valve is open and flowing.

So DPFE is the main input to the PCM for EGR Valve (Control) of the flow, that flow is delivered to the intake manifold.

The MAPT sensor in the intake manifold has partial control of transmission shift points as the shift points come from engine load in addition to fuel delivery and ignition timing along with the other needed inputs (Engine Temp & RPM and Vehicle Speed)

So, NO the DPFE does not directly affect the transmission (shift points) but the EGR Flow does with what the MAPT sensor is reading (so indirectly it does)
So the Buck/Surge is actually coming from the MAPT sensor (pick up) and the sensor adjusting fuel delivery and timing.
In short the MAPT sensor is picking up its under a load, when it actually is not, this throws off the shift point pattern, this is why and how a transmission issue can be misdiagnosed and lead you down the wrong path.
With this symptom and it not coding - you must know what to look for in the Live Data PIDs and that is the EGR Open and DPFE (Pressure/Voltage) readings and view the MAPT Sensor (Pressure/Voltage) reading.
The MAPT sensor reading should increase when EGR is flowing (valve opened) and drop back when the EGR (valve closed)

 

[Tim H.]

Its more about the sensor that sees the pressure changes in the Intake Manifold when the EGR Valve is open and flowing.

So DPFE is the main input to the PCM for EGR Valve (Control) of the flow, that flow is delivered to the intake manifold.

The MAPT sensor in the intake manifold has partial control of transmission shift points as the shift points come from engine load in addition to fuel delivery and ignition timing along with the other needed inputs (Engine Temp & RPM and Vehicle Speed)

So, NO the DPFE does not directly affect the transmission (shift points) but the EGR Flow does with what the MAPT sensor is reading (so indirectly it does)
So the Buck/Surge is actually coming from the MAPT sensor (pick up) and the sensor adjusting fuel delivery and timing.
In short the MAPT sensor is picking up its under a load, when it actually is not, this throws off the shift point pattern, this is why and how a transmission issue can be misdiagnosed and lead you down the wrong path.
With this symptom and it not coding - you must know what to look for in the Live Data PIDs and that is the EGR Open and DPFE (Pressure/Voltage) readings and view the MAPT Sensor (Pressure/Voltage) reading.
The MAPT sensor reading should increase when EGR is flowing (valve opened) and drop back when the EGR (valve closed)

You explained it better than I could…thank you!

 

[ronbaker33]

My 2020 Lariat w/49k is at the dealer now for delayed reverse in cold weather, surging at cruise speeds, rough shifting especially downshifts…feels like someone hits the rear bumper slightly. Just got a call from the service guy. Ford says this is normal behavior. I call BS! Last Ford I’ll ever buy! I hope they enjoy screwing their customers because they are bleeding buyers by the thousands because of their policies.

I have dealt with the same issue. I have found problem goes away if you start the engine. Allow for the high idle to go to normal idle speed and then shift into gear on those cold weather days. I have a 2019.

 

[ctechbob]

I have dealt with the same issue. I have found problem goes away if you start the engine. Allow for the high idle to go to normal idle speed and then shift into gear on those cold weather days. I have a 2019.

Here's something else you can do as well is.

Start the truck
Shift down into neutral and pause for a second - This signals the ECU that you're getting ready to engage a gear and it will idle the engine down almost immediately. Once that happens, shift into Reverse or Drive and off you go,.

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