Howdy All,
I've dug around and could not find much on my issue.
I have a 1999 F150 5.4 with a 4R70W.

The tranny will shift fine if I keep a light foot, but if i step on it a little bit it acts like there is no overdrive and won't shift until 2500-3000 rpms.

It also does this after it's warmed up, but only for a short time.

I've changed filter, flushed tranny (with Lucas added), and changed TPS.

I hope I've supplied enough info to solicit some help.

Many thanks, in advance.

/**04/08/2014**/
Edited Title

 

My experience has always been, the more you crowd an automatic, the longer it takes it to shift.

 

Ya I think I wasn't as clear as I could've been. It's not that it just takes a while to shift when pressing on it, the issue is that after pushing on it and then driving normal, it gets 'stuck' so to speak. Plus, I would think driving on the highway at 1500 rpm would be crowding it. After I get off the highway, slow down, and gradually accelerate again, it does the same thing.

I appreciate the reply though.

 

Have you checked the OBD2 for trouble codes with a scanner capable of reading Ford transmission codes? Has the OD Off light ever flashed?

Lucas should not be used in a healthy transmission. It can cause as many problems as it claims to fix.

 

It has no codes active or in history. I can't say that I've seen the OD light flash at all. I may have missed it (given the position), but don't think so.

Good to know about Lucas, thanks. Although I have to say that I have not noticed any difference since the flush (about 10K miles ago).

 

Ok, so I noticed something else which makes me wonder if it's even the tranny. Whilst it was having symptoms I put it in park and the idle was at 1300 rpms instead of the normal 600. That would make sense that the shift points would be skewed. I will continue my search, thanks for your thoughts.

 

High idle is usually either a vacuum leak or a sticky IAC. Could also be a dirty throttle body, throttle plate not closing far enough.

 

Well, to report...
Changed IAC, cleaned TB, sprayed remaining chem tool all over vacuum lines. Issue persists. I'll post this in a different section as I'm not so sure it has anything to do with the transmission. Thanks for your input.

 

No, please don't crosspost - ask a moderator to move it if you think it needs to be moved.

 

I would ask, but not sure I see a way to. Do I just request here? If so, Mod please move.

 

Looks like it's moved!

In the future, you can use the REPORT POST button - that's the little red triangle at the upper right of the post with a ! in the middle.

 

Ah cool. Thanks glc.