BensKingRanch

I am in need of some help. I am very mechanically inclined, but I don't have much transmission experience.
Backround; 06 f150 king ranch 4x4 with 5.4 136000 miles. level, CAI and tune. Mods have been on the truck for 15k + miles. Well maintained, and kept in great shape. No other signs or symptoms. When I am driving (in D) it feels like it's slipping into neutral. If I accelerate with my foot on it, the truck will get up to highway speeds. When I take my foot off of the gas for a second and then step back on it, it feels like its in neutral (revs up with no resistance and the truck no longer accelerates) eventually it will "find" a gear. If I accelerate moderately or lightly it seems like it "slips" into neutral while I still have my foot on the pedal. It drives normally in "1" and "2", and I have tried it with OD on and off. This started suddenly tonight, there has been no previous slippage or hard shifting. Fluid flushed/ replaced approx 10k miles ago with max life. Fluid level good and fluid is clean, does not smell burnt. There is no chatter, scrape, clunk, grind or any other noise. It acts exactly as if I have shifted it into N while driving. I need some direction on where to look.
Thanks in advance for any advice.

BensKingRanch

Nobody?
*sings "all by myself, just wanna be all by my self"

jday47

Sounds like the tranny is starting to slip, could be variety I things in the trans causing it but regardless the only fix is gunna be a trans rebuild or a new transmission, if the trans flush was pretty recent there is the slim chance that the flush disturbed some settlement internally and caused it but that hardly ever happens, so unfortunately ur prob looking at a new trans. To be sure just have a shop check it out

BensKingRanch

Yeah, it's in the shop now. Getting a rebuild and some upgraded transmission components while I'm at it... Plus a new upgraded torque converter

jday47

Sweet sounds awesome

JJ_Mac

I was having some similar slipping issues in my 2000. It turned out it was leaking trans fluid from the cooler lines. Changed em to rubber (used fuel lines with double hose clamps on each end), got the fluid level back up to par, problem solved. Oh the joys of steel lines with Canadian weather...

BIGDAWG2

My 2004 FX4 started the same thing yesterday will not pull at all in OD. Taking it to tranny shop on Friday. What converter are you going with? How much is your rebuild costing?

Mpyre

I am curious also since I'm having slipping issues too. How much should a rebuild cost? Is it better to buy new or go with remanufactured an do a core exchange?

DieselDayne9311

My tranny was starting to slip as well. When i accelerated to 35-40ish it would jump back and forth between gears. Turns out my Direct clutch is burnt out! In the shop yesterday. Buddy owns the shop and said 2100-2400$ for HD rebuild!