shifts fiine though gears. but at WIDE OPEN doesnt want to shift. any ideas thanks?

 

I'd guess something is wrong.

That's as detailed as I can get with all the detail you've provided, such as what kind of vehicle we're talking about, engine, 4x4 or not, trans, etc.

 

4x4 97 f150 4rw70trans

 

The first thing to do is to change the fuel filter. That's the most frequent cause of WOT shift issues with an electronic trans. The engine is starved for fuel so it can't accelerate to the WOT shift speed. Next check/change the air filter. Same reason.

If that doesn't do it you'll need someone with a REALLY good scan tool that can look at the inputs and outputs of the PCM to see what's not working right at WOT.

 

any type of tuning change lately?

Some times if the rev limiter is set to close to the shift point the trans will not shift..

 

I am betting that the intermediate one way clutch is on it's way out and not allowing you to make a WOT 1-2 shift.

Darrin

 

I have an 04 FX4 4x4 and just had the same issue. Shifts fine during normal driving but in WOT it doesn't want to shift. If I let off of the gas a little then it shifts fine. I just had it serviced and they changed the fuel filter, maybe I need to clean and oil my k&n air filter.

 

What would this cost to get replaced?