2021 Powerboost erratic shifting when highway towing

[Jondj]

The thing that really concerns me is that Ford dealerships don’t seem to be able to repair these transmissions when they have problems like mine. On a number of very similar threads the customers ended up with a new transmission after months and multiple visits like I did. I also only have a little more than 16,000 miles on the truck so it’s still under warranty if not this would be costing me a fortune! Not to mention the thousand of $ it still cost me since we were travelling and I had to cover extra expenses while waiting for the truck to supposedly get fixed only to have the problem come back every time. Maybe they will get all the “kinks” worked out of these but only time will tell.

The gear shifts would jump from 9 to 7 and then back up sometimes even 6 so I saw from 1800 up to 3700 rpmwithin seconds. It was really crazy and I got some videos of it and showed them to the Ford dealership in Mesa.

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[Snakebitten]

If you watch a 10r80 complete teardown and the fella includes a description of each element, as well as how the assembly functions, you get the idea that it's not likely each dealership has someone on staff wiith the necessary expertise to isolate and successfully repair them.

At least I don't think it's likely.

Depending on the malfunction, I would just have them replace the transmission and then ship the core to a facility with the expertise to get the transmission back to perfect working order. Then it goes into the replacement circulation for warranty repairs.

 

[Jondj]

The Saga continues after 12 days at the dealer in Idaho Falls and a complete new transmission assembly as well as both axles replaced as per the recall as the RH axle bolt was broken.
Anyway I got a call Friday AM stating the truck was ready to go and had been road tested etc so I drove 10 hrs down to pick it up along with my trailer.
Sat morning I picked up the truck and drove around for about 20 minutes of mixed driving and everything seemed okay so I hooked up my trailer for the drive back home. Left at 10 AM and drove I15 North at highway speeds between 55 and 70 depending on terrain. Truck seemed to be running at normal temps and shifting well even going up steep grades and over the multiple passes. About 7 hrs into the drive coming out of Great Falls Mont with a long gentle uphill grade driving around 70 all of a sudden the truck starts doing some real hard downshifts into 8th and 7th gear and then I notice that the transmission temp which had been rock solid in the middle of the gauge all day started to go up quickly. In a matter of less then a minute or so it went into the high temp zone and I slowed way down and pulled over and the temp went down slowly back to normal. A strong smell of a overheated transmission permeated the truck. I continued at a slower speed to the border and then back up to highway speeds north of the border with no further problems although it is very flat terrain to Calgary. One other thing the outside air temp was between 1 to about 11 C all day and raining and light snow so that definitely shouldn't be a factor.

Tomorrow I will call my local dealer and make an appointment (5th one) what else could be the problem after the transmission assembly was replaced? The dealer in Mesa flushed, pressure tested and replaced the valve and control for the transmission cooler after one of the earlier overheating episodes.
This is a nightmare as it only seems to happen during towing and after longer grades so replicating it easy is almost impossible!

 

[Snakebitten]

Long grades and towing.
Overheating transmission.
70mph

Perhaps you are exceeding the cooling capacity of the truck?

Do you have a way of monitoring actual transmission temps, rather than the pathetic instrument cluster graphic? By the time that thing alerts you of concern, things are already well beyond normal.

 

[Mosey]

About 7 hrs into the drive coming out of Great Falls Mont with a long gentle uphill grade driving around 70 all of a sudden the truck starts doing some real hard downshifts into 8th and 7th gear and then I notice that the transmission temp

This implies you were in either 9th or 10th gear. That is way too high. Lock out 9 and 10, and maybe even 8th. 8-10 are all overdrive ratios. You may even see your fuel consumption improve as the engine will not be in boost as much.

Reading back in this thread you never mention what you are towing, weight, height, etc..

Lastly, based on the limited information in this thread, two commonalities are your trailer load and long uphill grades. TFL overheated an F-150 tranny during a tow test. They discovered that Ford specifies lower tow loads as you go up in elevation due to cooling effectiveness.

 

[Jondj]

I definitely understand your questions and those would be the first thing that would come to my mind.
First off the trailer is a 36 ft cougar travel trailer a little over 7000 lbs loaded so well under the truck specs. Also I did almost this exact same trip in the middle of last summer with temps in the mid 30C or around 100 degrees F and it never moved off the midline in temp. No shifting problems nothing. I did try running it in 8th gear on one of my early instances on this trip and it still overheated.
Being so close to the mountains here I have been towing this exact same trailer up grades for the last two years with absolutely no problems.

It all started with the errors on that aux transmission pump last fall on my trip down South.

Embarrassing when a 30 year old beater motorhome towing a F150 passes me with flashers on going 55 to 60 up grades so I wont overheat!

One question I have is when they say they swapped out the transmission assembly what does that actually include??

 

[Jondj]

As far a monitoring transmission temps outside the gauge on the truck I am not sure how you would do that unless I could access more info from the ODB2 port when I am driving?

 

[Snakebitten]

Lariat and above do not need to access the OBD port to get the transmission temps displayed in real time. (Forscan edit)
That transmission temp gauge doesn't move graphically for a considerably wide range of temperature. The ECT gauge is just as misleading.

 

[Jondj]

Okay now that I am back home I have access to Forscan tools so I will see how to display the temp all the time. Normally it just moves the dial until it gets into danger zone then it displays the temp until it drops back down into the normal range. Your right it would be very useful to have it display the temp all the time.

 

[Jondj]

Okay now that I am back home I have access to Forscan tools so I will see how to display the temp all the time. Normally it just moves the dial until it gets into danger zone then it displays the temp until it drops back down into the normal range. Your right it would be very useful to have it display the temp all the time.

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