Good news, I have confirmed Pioter's findings at my Ford dealership. My surge/bucking issue was caused by the Differential Pressure Feedback EGR (DPFE) Sensor. I read through this entire 5 year topic and conducted several of the test noted and provided my dealership the below write-up:
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To help with your troubleshooting, I have done some diagnostics over the past couple weeks and offer the following notes:
Issue:
Vehicle has hesitation on soft acceleration and shutters/bucks at low speed cruise conditions (15-35 MPH). Situation is most prominent after first start of the day but has progressed to the point it can be felt almost anytime. All modules were evaluated for DTC codes with none present.
Observations:
Conducted series of live parameter monitoring on vehicle through OBDII and noticed the accelerator pedal signal is “noisy” between 1000 and 2000 RPM. This can be seen without reader in the tachometer reading by placing foot on brake and selecting Neutral. Attempt to hold engine speed at 1500 RPM using accelerator pedal and notice tachometer jumps around as well audible indication that engine speed is fluctuating rapidly. Would only expect speed to increase from stationary pedal position until throttle position/turbo boost balance. Speed jumps up and down rapidly.
Another unusual item is the EGR control system appears to be fluctuating in this low speed/low throttle position range. The impact of this was confirmed by disconnecting the DPFE sensor that is upstream of the EGR valve. When disconnected the shutter/bucking issue completely goes away.
DPFE Sensor
One other observation that leads me to believe the issue is a combination of the two items above; if you are experiencing the shutter/bucking and place the vehicle in cruise control the shutter/bucking stops. I think placing into cruise would remove the noisy accelerator pedal signal from commanding the throttle body position and other system functions. The smoother cruise control signal appears to keep the EGR system from fluttering.
My thoughts as a backyard mechanic and engineer:
I think the EGR issue is the primary cause with the accelerator pedal position sensor secondary. The EGR system issue could either be soot/contamination buildup in the EGR system that is impacting the DPFE reading or it is the DPFE sensor.
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Ford initially told me they could not repeat the bucking/shutter and I insisted on talking to their technician. The called me back to ask if they could keep it another day to have a "transmission expert" who was coming to their dealership look at it. They never noted if the "transmission expert" reviewed my Edge but said the DPFE was replaced and the vehicle is now "operating as designed at this time."
Overall I believe the issue is in the EGR system. Some of you have experienced this issue very early which could be the DPFE or a bad orifice in the EGR plumbing impact the pressure reading.
Good luck!
