I have a 2001 F250 Superduty - 5.4l 4-speed auti 4X4 Manual Hubs.

Lately, when cold, the truck is not dropping into Overdrive at highway speeds as it normally does.

I am not getting any check engine lights or any kind of other indications other than the RPM's are higher than usual and my milage is very poor.

Any thoughts?

 

Does it go into overdrive once it has warmed up? There is logic in the PCM that does not allow the torque converter to lock when the trans is cold, but it should shift to overdrive.

 

have you checked fluid level?