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Discussion Starter #1
Hello again.
1999 Ford F250 PSD 7.3
Had some issues earlier but you guys helped me fix those

Ended up replacing/doing this so far to fix previous issue. Found here

I rebuilt all 8 injectors myself
replaced all 8 glowplugs
replaced CPS from ford
replaced IPR from ford
replaced ICP from ford
replaced pigtail to ODD injector bank UVCH
replaced fuel filter
replaced fuel bowl heater
dropped fuel tank and found pickup screen broken so I modified it and bypassed the two screens in the pick up tube, thanks dieseltechron

Now new issue, still experiencing a loss of power but what's different now is I can get up to 50mph. The problem is it seems as though it won't shift when it needs to. At 50mph I'm around 2600rpm with pedal to the floor, when I slowly let off it still won't shift. The SES light doesn't not come on but when I read the DTC's using ForScan I get P1247 Turbo boost pressure fault - low.

My question is are these related issues or are the separate issues, do I have a low boost pressure issue as well as a transmission issue or is the low boost pressure causing the no shift issue?

As always your help is greatly appreciated.
 

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they are two different issues.. the transmission sounds like something is internally bad such as a shift solenoid
 

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Discussion Starter #3
awesome, do you know of a way to confirm? I heard that you can unplug something, I would assume the electronic plug, on the transmission and it'll put it into 4th gear, or a safety mode. Can you confirm. I'm curious to try this because I feel like I'm not shifting into 4th. If I do have a solenoid issue I would assume it won't run because it wouldn't be allowed to shift into 4th gear due to the bad solenoid correct?
 

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awesome, do you know of a way to confirm? I heard that you can unplug something, I would assume the electronic plug, on the transmission and it'll put it into 4th gear, or a safety mode. Can you confirm. I'm curious to try this because I feel like I'm not shifting into 4th. If I do have a solenoid issue I would assume it won't run because it wouldn't be allowed to shift into 4th gear due to the bad solenoid correct?
No you can't unplug anything the solenoids work with fluid take it to a transmission shop
 

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Discussion Starter #5
I don't want to take it to the transmission shop that's why I'm a member here so we can figure this out. So I watched a great video on youtube.


It explains the same problem I am having. I pulled the valve body and found the same thing he did in the video, the 2-3 shift valve was stuck open. I ordered a new valve and spring and installed and put everything back together. Same issue it won't shift into 3rd. This time however the OD light started flashing. I used Forscan and pulled P0708 code. I pulled the 4 electrical connections I could find on the transmission and they all looked dirty so I cleaned them all with contact cleaner. Started the truck and the same thing I can't shift into 3rd. I've been doing a lot of reading and I've read anywhere from an OSS to a VSS being bad to a torque converter. I've also read that if I have R then that's a good sign and it's most likely electrical. So I'm not sure what to do. The sensors are only about $15/ I'm thinking I might just replace each sensor one at a time to see if it fixes the problem.

The question I have is would their be a way to diagnose if a particular sensor is causing the issues and I can start their? Or should I be focusing somewhere else?
 

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Discussion Starter #6
So I replaced the 2-3 shift valve, like the video suggests, and pulled all the connections off and cleaned them up with contact cleaner. Reinstalled everything filled with fluid and drove it around. Still the same issue. Drove it a little longer and it eventually shifted into 3rd gear then right back into second. Drove a little longer and got it to shift into 3rd again then I maintained that speed and kept it in 3rd. Slowed down and started driving again shifted great all the way through 4th. Problem solved.
 
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