Edit: See below. Problem solved.

 

Odd shifting at WOT is a known issue. The governor pressure sensor gets saturated, and confused.... Replacing it *might* fix it.

Were the internal electronics change when the trans was rebuilt?

 

It's a reman, not a rebuild, so I'd imagine the answer to that is yes.

Think the governor sensor could be at the root of the 1st gear issue? I get the sense that what it's trying to do is shift but then decides it doesn't actually want to shift, so it slips a little then goes back into first. Like I said, no slippage if I manually hold 1st, so it's not a clutch thing.

 

Manual first is a different hydraulic circuit within the trans......

Could try disabling the electronics altogether..... Unplug the 8 pin connector at the trans, go for a drive, keeping in mind you will have ZERO automatic function. (No O/D or TCC either.) You will have to shift manually, up and down. So, go for a short drive, shift when you need to. If the trans goes into the gear you tell it to, when you tell it to, then it is indeed just an electronics problem, and replacing them should solve the issue. Borg Warner offers a 'heavy duty' governor solenoid, that is highly recommended as a replacement for the stock piece. For about 200 bucks, you can get ALL the electronics in the trans. (pressure sensor/solenoid, tcc and o/d solenoids, plus, the output speed sensor as well. Yep, the 'shotgun' approach.) That should make for a happy trans.

 

Great advice as always. I'll look into this soon.

...first priority today is replacing the radiator that started leaking haha. I just keep telling myself that at the rate I'm going replacing parts, I'll have a new truck in a year or two

 

As soon as he said it shutters in first and right before the 1 - 2 shift I thought Governor Pressure Solenoid. Mine was clogged like this (Actual picture of my solenoid). Replacing mine took care of the issue. I wonder if they actually replaced it or if they left it in.

 

Update: Finally got around to throwing a governor solenoid and the transducer. Governor was a Borg Warner, not sure if it was a Heavy Duty or not. It was in a 3rd party box.

I had the parts lying around from a previous issue. ETE shipped me a bunch of parts in an effort to avoid warrantying the trans and I didn't end up using them. Put them in today and....no difference. Front band adjustment didn't help either.

Fluid looked and smelled great. Not much debris on the magnet in the pan.

Ugh. Not sure where to go from here.

 

Time to chat with your rebuilder again, I suspect you have an internal failure of some variety.

 

edit: no longer correct

 

Right there in the service manual is most likely my issue. Faulty overrunning clutch. **** me...

Ordered an OTC pressure testing kit to go through the testing procedure to be sure.