First off - '04 F-150 screw 4x4 5.4L with the 4r75e

When driving, shifts up fine, but upon slowing down from somewhere in the 50mph OD (3rd) gear, it doesn't want to down shift into 2nd unless I get below 40. So, if at around 45 I hit the gas again, the torque convertor shutters until I'm back up to 50, or unless I floor the pedal to force it to downshift.

My girls got the same truck and if I do the same thing, as soon as I reapply pressure to the pedal at around 45, it goes smoothly into 2nd and accelerates fine.

Now, I'm thinking a few possibilities.
1. Since I'm getting torque convertor shutter, the lockup is sticking, and somehow not allowing fluid pressure through the convertor to tell the tranny to downshift. (or is the tranny shifting computer controlled)
2. If the tranny shifting is completely computer controlled, maybe the program in the computer from the previous owner has different shift points.
3. The clutches in the tranny are going bad (88000 miles)
4. The throttle position sensor ( thats what the potentiometer attached to the gas pedal is right??) is going bad, or has a bad spot in it.

Or, maybe my computer is throwing codes and I don't know it.. I haven't checked it yet.

Right now, I'm really at a loss and am not sure which of the numbers above to start w/. I"m hoping someone else has had this problem before also.. If, PLEASE CHIME IN.
Thanks

 

The transmission is computer controlled. The problem is that you don't like the way it was programmed. There is nothing wrong with the transmission.

 

Theres a couple things wrong here.
In these trucks, OD is 4th. So when it downshifts out of OD, you're going into 3rd, not 2nd. You would only get 2nd if you really floored it.

I'm kind of confused by your post, my truck doesn't downshift from OD(4th) until I hit 40 either. Pretty sure its normal....

 

I guess I am mistaken, I was thinking that OD was 3rd... so then yes, I'm in OD (4th) going about 50, let off the gas and coast slowing to 40-45.. when I get back on the gas to accelerated back to 50, the torque converter (I think) shutters pretty bad, almost like when driving a manual and trying to start from a dead stop in 3rd gear... where as in my girlfriends truck, it down shifts to 3rd, and smoothly accelerates to about 46-47 and then shifts back to OD. In my truck, to get it to down shift from OD (4th) I need to stomp on it and it ends up shifting into 2nd, not 3rd. ( just took both trucks for a spin and there is definately something up with mine )

If it was a matter of me "not liking the program" then why would it happen in my truck and not her truck?? exact same truck - '04 screw 5.4L etc

If your saying the tranny is completely computer controlled, then it would probably be the program right? Or are there valve bodies in the tranny that could go bad causing it not to shift right... Like I said, my first premonition was the torque convertor because I'm getting that shuttering.

 

Changing the trans fluid, including the fluid in the torque converter, will usually fix torque converter shudder.

 

I think that is going to be my plan of attack over the weekend.

I remember seeing thread on flushing a tranny, should I do that, or just drain the pan and convertor? ... what about the tranny cooler? will it drain with the pan and convertor?

and I think I remember seeing people saying that it's not worth it to get a new pan gasket because the old one is reusable.. In all my gasket experiences, I've always replaced them.

and then also, what about the tranny filter. I saw one guy saying to change it and another saying that it was designed not to be changed or something.

Thanks all....

 

Read THIS post for step-by-step on how I did a tranny flush at home. Worked quite well!