2003 5.4 Transmission issue

[CAndy1995]

My 2003 XLT 4x4 shifts through the gears smooth as butter. Even on hard acceleration it shifts just fine. The problem is at highway speeds if I go accelerate hard to make a light and the transmission downshifts it will slip. To narrow is down, at about 60 I took the truck out of overdrive and on the downshift is when it slipped. It doesn’t slip downshifting to any other gears. It appears to only be from O/D to 3rd or 4th (whatever gear is next below O/D)

Sorry if this was already brought up in a previous forum. I searched with no luck.

 

[mbtech2003]

Valve body separation plate is know to crack on those and do funky things. Bring it to a shop for fixing. Depending on mileage a full rebuild might be in order to update whole transmission. Do it before you have an extra neutral.

 

[Mikeyb1014]

Make sure that you don’t have any engine misfires too before assuming it’s strictly a transmission related issue. I had two mechanics telling me I had a bad torque converter and had me convinced I’d be tearing my tranny down come spring. $35.00 and an ignition coil on cylinder 1 later, no more “tranny” shift issue.

My problem was above 40 I’d start kicking in and out of gear. Turns out the miss was causing it all along.

Not saying it’s your problem, you’d just be surprised though.

 

[Old Guy]

When is the last time you had the tranny fluid and filter changed?