Thank God I found this site...This question has been bothering me for ever. I am driving a 1990 F-150 4x4, 5.0 with an AOD tranny. It seems like it won't shift down under acceleration in drive (not over-drive ) until it hits 48 MPH...everytime. Going up hill it will lose power down to 48MPH and then shift to 2nd and hold till about 4000RPM then shift up and start all over again, down to 48MPH and shift down again. I am running 33/10.50 tires which I didn't think would affect it. I don't know what it does with stock tires........HELP..chip?...gears?...adjustments?.. .????

 

Please.somebody help.......no news on this shift question among all the experience out there.................

 

Man I was hoping to get some help out there from my fellow Ford truck enthusiasts.........

 

Try posting in computer chips or engines. This sounds more like a PCM issue than a tranny. But you may be on to something with the tire size.

 

the AOD trans is not computer controlled. if everything is in good working order and if ur running on stock 3.55 gears then the 33x10 are to big. the 5.0 motor is just not strong enough so the trans shifts alot trying to find the right gear but bigger tires threw it off. its either regear, go to a smaller tire or make more horse power and torque

 

the tire size is 31/10.50 . A little under the 33's and i was hoping that they weren't to big of a difference..they may be.Thanks for the info.