Bucking/Surging Epidemic

[BladeRanger]

I’m trying this next

https://www.tsbsearch.com/Ford/20-2339

Let us know how it goes.
The dealer did some chemical cleaning on the valve and it helps with surging plus I replaced the EGR sensor as well.

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[4x4AZ]

Just adding my personal experience with this on my 2021... Just hit 43,000 today.

I had an incident a few weeks ago where I took off from a stoplight to make a hard left turn and the throttle literally did nothing for 3-5 seconds no matter how hard I pushed. Truck was fine after, but a weird experience. No codes thrown. Have also been having some very hard shifts especially at low throttle and low speeds. When I really noticed something was wrong was soon after I replaced my spark plugs with NGK laser iridium plugs. I had the characteristic "bucking" described by so many others above, very pronounced between about 20 and 55 at low throttle inputs or when locking into a gear with the RPM between 1000-1400. Also the truck would sort of "bang" into gear when dipping into the throttle after taking the foot off of it for a minute. I assumed that the truck just didn't like the NGK plugs, and of course I first noticed the issue on a road trip, so I ended up picking up a set of Motorcraft plugs and swapping them in at the Autozone parking lot, lol. Thought it helped at first but nope, plugs were not the issue. Found this thread and read through it, seems very common and almost the same exact symptoms of my truck.

I have 0% confidence in my local Ford dealer's service department, especially since the last time I took the truck in it had a very obvious slip yoke lube problem I wanted fixed, they "test drove" my truck (I know because I was in my work truck on the interstate and they came off an on ramp in MY TRUCK doing 15+ over the speed limit), kept it for 2 days, and told me nothing was wrong. So I just decided to buy the part myself and not even mess with the warranty to keep those dipshit's hands off my truck.

Ended up installed the part referenced previously lb5z-9j433-b, decided to go with the version including the hoses and clamps for simplicity sake. In the future, I'm just going to get the sensor only and swap from the ford spring clamps on the sensor side to a small hose clamp and call it a day. Not a bad job, took me about 30 minutes but I was going slow. Mostly just hard to reach, recommend having some good needle nose pliers for the hose clamps. When I pulled the sensor off, there was visible moisture inside it and the interior of the hoses were damp.

Test drive showed that my issues were solved! I still hate the way the 10 speed shifts and it will just never be smooth, but I'm at least back to the previous level of drivability before this happened. No more jittering and feeling like I'm driving a broken truck. Thanks to those of you who researched and solved this issue.

 

[Callthecops007]

Just adding my personal experience with this on my 2021... Just hit 43,000 today.

I had an incident a few weeks ago where I took off from a stoplight to make a hard left turn and the throttle literally did nothing for 3-5 seconds no matter how hard I pushed. Truck was fine after, but a weird experience. No codes thrown. Have also been having some very hard shifts especially at low throttle and low speeds. When I really noticed something was wrong was soon after I replaced my spark plugs with NGK laser iridium plugs. I had the characteristic "bucking" described by so many others above, very pronounced between about 20 and 55 at low throttle inputs or when locking into a gear with the RPM between 1000-1400. Also the truck would sort of "bang" into gear when dipping into the throttle after taking the foot off of it for a minute. I assumed that the truck just didn't like the NGK plugs, and of course I first noticed the issue on a road trip, so I ended up picking up a set of Motorcraft plugs and swapping them in at the Autozone parking lot, lol. Thought it helped at first but nope, plugs were not the issue. Found this thread and read through it, seems very common and almost the same exact symptoms of my truck.

I have 0% confidence in my local Ford dealer's service department, especially since the last time I took the truck in it had a very obvious slip yoke lube problem I wanted fixed, they "test drove" my truck (I know because I was in my work truck on the interstate and they came off an on ramp in MY TRUCK doing 15+ over the speed limit), kept it for 2 days, and told me nothing was wrong. So I just decided to buy the part myself and not even mess with the warranty to keep those dipshit's hands off my truck.

Ended up installed the part referenced previously lb5z-9j433-b, decided to go with the version including the hoses and clamps for simplicity sake. In the future, I'm just going to get the sensor only and swap from the ford spring clamps on the sensor side to a small hose clamp and call it a day. Not a bad job, took me about 30 minutes but I was going slow. Mostly just hard to reach, recommend having some good needle nose pliers for the hose clamps. When I pulled the sensor off, there was visible moisture inside it and the interior of the hoses were damp.

Test drive showed that my issues were solved! I still hate the way the 10 speed shifts and it will just never be smooth, but I'm at least back to the previous level of drivability before this happened. No more jittering and feeling like I'm driving a broken truck. Thanks to those of you who researched and solved this issue.

I did all you did too and didn’t work for me. When I replaced the valve it stopped for like 2 days then went right back. Finally I had to take it to dealer and have them rest the computer for transmission. Completely fixed my issues.

 

[airline tech]

Just adding my personal experience with this on my 2021... Just hit 43,000 today.

I had an incident a few weeks ago where I took off from a stoplight to make a hard left turn and the throttle literally did nothing for 3-5 seconds no matter how hard I pushed. Truck was fine after, but a weird experience. No codes thrown. Have also been having some very hard shifts especially at low throttle and low speeds. When I really noticed something was wrong was soon after I replaced my spark plugs with NGK laser iridium plugs. I had the characteristic "bucking" described by so many others above, very pronounced between about 20 and 55 at low throttle inputs or when locking into a gear with the RPM between 1000-1400. Also the truck would sort of "bang" into gear when dipping into the throttle after taking the foot off of it for a minute. I assumed that the truck just didn't like the NGK plugs, and of course I first noticed the issue on a road trip, so I ended up picking up a set of Motorcraft plugs and swapping them in at the Autozone parking lot, lol. Thought it helped at first but nope, plugs were not the issue. Found this thread and read through it, seems very common and almost the same exact symptoms of my truck.

I have 0% confidence in my local Ford dealer's service department, especially since the last time I took the truck in it had a very obvious slip yoke lube problem I wanted fixed, they "test drove" my truck (I know because I was in my work truck on the interstate and they came off an on ramp in MY TRUCK doing 15+ over the speed limit), kept it for 2 days, and told me nothing was wrong. So I just decided to buy the part myself and not even mess with the warranty to keep those dipshit's hands off my truck.

Ended up installed the part referenced previously lb5z-9j433-b, decided to go with the version including the hoses and clamps for simplicity sake. In the future, I'm just going to get the sensor only and swap from the ford spring clamps on the sensor side to a small hose clamp and call it a day. Not a bad job, took me about 30 minutes but I was going slow. Mostly just hard to reach, recommend having some good needle nose pliers for the hose clamps. When I pulled the sensor off, there was visible moisture inside it and the interior of the hoses were damp.

Test drive showed that my issues were solved! I still hate the way the 10 speed shifts and it will just never be smooth, but I'm at least back to the previous level of drivability before this happened. No more jittering and feeling like I'm driving a broken truck. Thanks to those of you who researched and solved this issue.

Unfortunately, this issue is mainly a no-code issue for most owners. For a dealer technician no-code = no problem, unless he / she decides to dig deeper and actually test the system and most importantly what to look for and that is the DPFE sensor PID reading being out of spec but not bad enough to code.
I would love to see a TSB or at a minimum a SSM on this issue, this will at least get a tech's attention and dig deeper, instead of the owner is an idiot and imagining an issue.
For when it does code P139C, (the most reported code) it directs the tech to inspect the DPFE for moisture and replace if moisture is found.

 

[Racket]

Gets me thinking of rigging up a moisture separator from a compressor in there but what a maintenance headache.

 

[Callthecops007]

Unfortunately, this issue is mainly a no-code issue for most owners. For a dealer technician no-code = no problem, unless he / she decides to dig deeper and actually test the system and most importantly what to look for and that is the DPFE sensor PID reading being out of spec but not bad enough to code.
I would love to see a TSB or at a minimum a SSM on this issue, this will at least get a tech's attention and dig deeper, instead of the owner is an idiot and imagining an issue.
For when it does code P139C, (the most reported code) it directs the tech to inspect the DPFE for moisture and replace if moisture is found.

This is what I had done. It finally fixed my issues

 

[Yinzcity]

This is what I had done. It finally fixed my issues

In my experience, this will fix it for a while, then the transmission seems to learn itself into bad habits again. For anyone who wants to do this themselves, the reset of the adaptive learning can be done through forscan.

 

[RedlandRanger]

Just to clarify here - the problem part is a DPFE sensor, it is not the EGR valve. The EGR Valve is a separate part. Not being an A$$ just don't want others to be confused and tripped up on part names. The EGR valve is a $110 part, vs the DPFE sensor at $58.00 for complete assy

I'm a bit confused on the labeling of the parts - is part # LB5Z-9J433-B correct for the DPFE sensor?

 

[Callthecops007]

In my experience, this will fix it for a while, then the transmission seems to learn itself into bad habits again. For anyone who wants to do this themselves, the reset of the adaptive learning can be done through forscan.

What’s the next step after this ?
I’ve replaced the erg sensor. Air filter. Spark plugs.

 

[Yinzcity]

What’s the next step after this ?
I’ve replaced the erg sensor. Air filter. Spark plugs.

I've never got mine to be 100 percent smooth all the time. However, provided the egr sensor is good, resetting both the transmission adaptive values and the PCM learned values in forscan tends to make it decent for a while. One thing to watch out for, reset the adapts when the transmission is at operating temp and try to follow the service guide for driving for a bit after you reset. Basically light acceleration up and down through the gears a few times. I've found that when you try to relearn when the trans is cold, it doesn't adapt as well.

 

[airline tech]

I'm a bit confused on the labeling of the parts - is part # LB5Z-9J433-B correct for the DPFE sensor?

Yes, it is a bit confusing on the part name- as it is listed as Vacuum Control and Sensor, and some list is as a valve.

Borrowed Pic

Sensor Only - KA1Z-5L200-AB - Comes without the hoses, you will need to use side cutters to cut the silver clamps off of the old sensor and replace with worm clamps (5/16)
Current Price: $59.26 - Varies by Source
Note: I see varying dash numbers for this (-A) and (-AB) with searching for the sensor only, such as (-A) will be the listed P/N but the pic of part shows (-AB).
It is the same part though.

Kit - LB5Z-9J433-B - Sensor and Hoses - You have to have a small pair of needle nose pliers to get the clamps off of the tube ends, the new one comes with little plastic (finger) rings to ease with re-install - Access to these ends is limited, but doable.
Current Price: $78.62 - Varies by Source

Below is a pic of Old and New - DPFE Sensor - (Differential Pressure Feedback)

For Reference Only:

The below part: EGR Valve - P/N- LB5Z-9D475-B is the only VALVE in the EGR system, this part is Current Priced at $111.62.
Now the EGR valve itself will generate different codes; it is rare for them to fail.
This is the valve that is actually opening and causing the buck / surge drivability issues.
But it is receiving false readings from the DPFE sensor, and it is doing what the PCM is commanding from those false readings.
So, opening the valve when it should be closed, allowing unwanted EGR flow into the intake manifold. (at Idle and low RPM & Load conditions), this is the Buck/Surge.
Once you are at speed (cruise) you are overcoming this condition and not as noticeable
As the vacuum differential between the Upstream and Downstream flow (DPFE Sensor) has changed

 

[RedlandRanger]

Yes, it is a bit confusing on the part name- as it is listed as Vacuum Control and Sensor, and some list is as a valve.

Borrowed Pic

Sensor Only - KA1Z-5L200-AB - Comes without the hoses, you will need to use side cutters to cut the silver clamps off of the old sensor and replace with worm clamps (5/16)
Current Price: $59.26 - Varies by Source
Note: I see varying dash numbers for this (-A) and (-AB) with searching for the sensor only, such as (-A) will be the listed P/N but the pic of part shows (-AB).
It is the same part though.

Kit - LB5Z-9J433-B - Sensor and Hoses - You have to have a small pair of needle nose pliers to get the clamps off of the tube ends, the new one comes with little plastic (finger) rings to ease with re-install - Access to these ends is limited, but doable.
Current Price: $78.62 - Varies by Source

Below is a pic of Old and New - DPFE Sensor - (Differential Pressure Feedback)

For Reference Only:

The below part: EGR Valve - P/N- LB5Z-9D475-B is the only VALVE in the EGR system, this part is Current Priced at $111.62.
Now the EGR valve itself will generate different codes; it is rare for them to fail.
This is the valve that is actually opening and causing the buck / surge drivability issues.
But it is receiving false readings from the DPFE sensor, and it is doing what the PCM is commanding from those false readings.
So, opening the valve when it should be closed, allowing unwanted EGR flow into the intake manifold. (at Idle and low RPM & Load conditions), this is the Buck/Surge.
Once you are at speed (cruise) you are overcoming this condition and not as noticeable
As the vacuum differential between the Upstream and Downstream flow (DPFE Sensor) has changed

Thank you for the details. Interestingly enough, Levittown Ford Parts only lists the kit, not just the sensor.

Next question - where on the engine is this part located? If it was posted previously, my apologies - I didn't see it.

 

[airline tech]

Thank you for the details. Interestingly enough, Levittown Ford Parts only lists the kit, not just the sensor.

Next question - where on the engine is this part located? If it was posted previously, my apologies - I didn't see it.

Thank you for the details. Interestingly enough, Levittown Ford Parts only lists the kit, not just the sensor.

Next question - where on the engine is this part located? If it was posted previously, my apologies - I didn't see it.

Drivers Side:
By the Brake Booster, the sensor to the left of the DPFE is the MAPT Sensor, you can see a glimpse of the rigid tubing near the firewall that the DPFE hoses connect to.
This is one of those parts where you have to head dive into the engine bay to get to it.

 

[RedlandRanger]

Drivers Side:
By the Brake Booster, the sensor to the left of the DPFE is the MAPT Sensor, you can see a glimpse of the rigid tubing near the firewall that the DPFE hoses connect to.
This is one of those parts where you have to head dive into the engine bay to get to it.

Thank you again - that is very helpful. I can't say I'm looking forward to replacing this, but I'm pretty sure I need to. I only noticed it when I was in rush hour traffic - normally I don't drive in stop and go traffic so I don't notice it, but I really did notice it with the stop and go. Maybe I will just not drive in stop and go traffic.

 

[Marc S]

Finally got around to replacing it. It’s a pain to get to but man it’s night and day difference. Hopefully that fixes it because it makes me love the truck again!

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