Powerboost Transmission shifting is slipping

[Jondj]

I will add to the party. 21 PB, 57k miles. It has long had an issue where it would routinely skip 2nd gear too easily and bog down in 3rd at low rpm. Otherwise it seemed to work pretty well. I've had it reprogrammed at least twice, never solved the issue.

Then, in December of 23 two errors flashed across the dash display followed immediately by "Stop safely now" which turns out to mean "Stop--safely or not--you're coasting". No high voltage system, no ICE. Took it to the dealership. They traced the codes to a faulty Aux Transmission Pump. They replaced it. I got it back and didn't make it 30 miles back home with the same issue--two faults, I'm coasting. They looked at it again and determined the might have put in a bad replacement pump, so they replaced it a 2nd time. They had the transmission tech take it home after work as a longer test drive (I approved first). He didn't make it home either. After that, they replaced the entire hybrid drive unit and gave it back to me. I didn't make it home A 2ND TIME! It went back to the shop again.

After consulting with the Ford Tech Line folks, the shop techs determined to replace a wiring harness that was internal to the transmission. And THAT seems to have fixed the faults & shutdown issues. So far anyway. In fact, that actually fixed the original issue of skipping 2nd gear too easily. However, now that I have it back and have driven it around for a couple hundred miles, it is displaying exactly the behavior the OP described. The trick appears to be that it only happens when the transmission gets above about 180 F. I have a Platinum with a digital dash and the digital temperature is displayed below the dummy gage, so I can see real numbers (assuming the PIDs are correct). Starting from a cold transmission it takes me at least 30 minutes of driving to get the temp up to that level, but when it does get there it will slip from 9 to 10 when under any power, and from 4 to 5 or 5 to 6 when under heavier throttle, say as much as it would take to make it shift at 3500 rpm. Downshifts from 10 to 8 or from 8 to 6 can be very hard, but not always. I cannot yet reproduce that effect on command. Additionally, once up to that temp range between about 180 and 225, if I accelerate with some force (again, maybe letting it shift at about 3-4k rpm) the transmission generates a very noticeable whine. I have a 40 mile commute so I am seeing this every day now. Also getting a pretty strong ATF smell in the cab when I come to a stop, again only if the temp has reached 180 or higher.

I'll be calling the shop again tomorrow to let them know. We'll see what happens but this is getting old. I initially took the truck in at the beginning of December last year and only received it back (in a condition it will function for more than a few miles) last week.

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[Jondj]

I have an update on my situation I left yesterday on my trek back home and sure enough not even an hour into my trip pulling my trailer the transmission started it’s lurching and shifting problem. In addition the transmission suddenly started to overheat and went into the red flashing and giving me warnings so
I immediately pulled over to the side of the road and just left the engine running and it cooled back down to normal operating temp but that’s the first time that ever happened! I have had to stop my trip now and brought it in for service. I will let you know what they find but it only happens,when I tow so it’s almost impossible to recreate.

 

[bhizzler727!]

I have an update on my situation I left yesterday on my trek back home and sure enough not even an hour into my trip pulling my trailer the transmission started it’s lurching and shifting problem. In addition the transmission suddenly started to overheat and went into the red flashing and giving me warnings so
I immediately pulled over to the side of the road and just left the engine running and it cooled back down to normal operating temp but that’s the first time that ever happened! I have had to stop my trip now and brought it in for service. I will let you know what they find but it only happens,when I tow so it’s almost impossible to recreate.

Update?

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