1.5 engine surge

[preach]

New here. Maybe beating a dead horse. Have had my sons 21 base 1.5 for about 8 months. Engine constantly surging. From easing around back roads to cruse controls on the interstate. Have put a new battery, plugs, air filters, and cleaned mass air flow. Dealer has done all the updates on it but still doing it. They are no help. No codes so they can’t find any. Any one have any thought or is it just what it is going to do. Thanks

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[thomasm23]

New here. Maybe beating a dead horse. Have had my sons 21 base 1.5 for about 8 months. Engine constantly surging. From easing around back roads to cruse controls on the interstate. Have put a new battery, plugs, air filters, and cleaned mass air flow. Dealer has done all the updates on it but still doing it. They are no help. No codes so they can’t find any. Any one have any thought or is it just what it is going to do. Thanks

Explain this “surging” in detail please.

 

[preach]

Best way to describe it is like one is bumping the throttle repeatedly. Rpm jump up and down

 

[thomasm23]

Best way to describe it is like one is bumping the throttle repeatedly. Rpm jump up and down

Please read through this link.

https://www.broncosportforum.com/forum/threads/torque-converter-shudder-adventure.11649/

 

[DWG]

Bad EGR valve?

What you are describing is a little different than what I have experienced with my 2019 Edge an in extreme heat in my 24 BS but maybe might give you some ideas. In my case the bucking/surging only happens for a few minutes when I start driving in the local neighborhood until I get on the main road at low speed between 15 and 20 mph others on this thread have complained about it happening more than at just low speed. Some people felt replacing the EGR valve helped. Others said some more expensive fixes helped some said it did not help.

There have been TSB's on the Edge issue. TECHNICAL SERVICE BULLETIN 8F35 Transmission - Shudder/Buc k/Jerk While Driving Up To 35 MPH (57 Km/H) - Built On Or Before 11-Mar-2021 TSB 21-2389. Reflashing the PCM software diid not help. My dealer has told me in the past that the low speed surge/bucking is a known issue and there is no fix for it.

26728-edge-low-speed-surgebuck-transmission

Again not specifically your issue but here is thread I started on this forum back in Sept 2024 https://www.broncosportforum.com/forum/threads/surging-and-bucking-at-low-speed.12141/

 

[preach]

Your issue is a little different. Mine is constant, at any speed. Does it worse at lower ones as far as the affect of how it’s felt. I’m going to order the anti flutter additive that thomasm23 shared a link to a tread. Hope that will work

 

[DWG]

Yes, your issue is much worse that what I have been experiencing but I still wanted to put it out there because some people on the Edge thread did have the issue where it was more continuous, not just low speed and felt that the EGR valve replacement helped them. So maybe something to have checked.

How many miles on your BS and did the surging just recently start since you started driving it or was it something that has been happening for a while?

 

[Bucko]

Vacuum line leak perhaps.

 

[Colonel Angus]

Vacuum line leak perhaps.

My thoughts also.

 

[thomasm23]

Your issue is a little different. Mine is constant, at any speed. Does it worse at lower ones as far as the affect of how it’s felt. I’m going to order the anti flutter additive that thomasm23 shared a link to a tread. Hope that will work

Can you share some additional information about the vehicle?

How many miles are on the vehicle?
Was it purchased used?
Has the transmission fluid ever been changed?

Try this to diagnose.
Drive on a highway or freeway and set the cruise control to 65 mph. Watch the tachometer gauge. Does the gauge have a rhythmic jump every second?

The Lubegard Instant Shudder Fixx will help diagnose an issue. If by adding the Lubegard the issue is gone, you will have identified degradation in the transmission fluid.

 

[Mark S.]

Vacuum line leak perhaps.

Good thought, but I would think that kind of issue would generate a trouble code.

 

[preach]

Yes, your issue is much worse that what I have been experiencing but I still wanted to put it out there because some people on the Edge thread did have the issue where it was more continuous, not just low speed and felt that the EGR valve replacement helped them. So maybe something to have checked.

How many miles on your BS and did the surging just recently start since you started driving it or was it something that has been happening for a while?

Around 75k or so. I added the instant surge stop this afternoon and it’s seems to be fixed. It had got just about unbearable to drive. It’s my son’s rig. He is in college. He stays on a campus and only really drives it when he comes home. He was telling me how bad it was. Hope it fixed. Thanks for info

 

[preach]

Can you share some additional information about the vehicle?

How many miles are on the vehicle?
Was it purchased used?
Has the transmission fluid ever been changed?

Try this to diagnose.
Drive on a highway or freeway and set the cruise control to 65 mph. Watch the tachometer gauge. Does the gauge have a rhythmic jump every second?

The Lubegard Instant Shudder Fixx will help diagnose an issue. If by adding the Lubegard the issue is gone, you will have identified degradation in the transmission fluid.

Yes we got it used with 65k or so. Don’t have any clue in service. Did add the treatment you shared this afternoon and the problem went away. I am shocked that that worked the way it did. Thank you for your help.

 

[thomasm23]

Yes we got it used with 65k or so. Don’t have any clue in service. Did add the treatment you shared this afternoon and the problem went away. I am shocked that that worked the way it did. Thank you for your help.

Good to hear.

If the shudder comes back, I would do a back to back drain and fill using Motorcraft ULV transmission fluid. See my original post.

You probably should plan on a drain and fill anyway. The transmission and torque converter will thank you.

It makes me think of how many others are experiencing a torque converter shudder and are misdiagnosing the issue.

 

[DWG]

Glad to hear it seems to be fixed

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