My '08 F150 FX4 has done this since new. When I'm cruising along at a low steady speed (30 mph) it slips between 4th and overdrive, (revs up for a couple seconds). So I usually have to turn the overdrive off if I'm going to be putting around at work.
Is the transmission even supposed to shift to overdrive at that low of speed?
I haven't found the time to get it to the dealer yet.

 

It sounds like your foot isn't steady on the gas, because at 30MPH it'll shift into OD if it's at or near 0% throttle. Then when you press the pedal after you lifted off, even just a little bit, it'll shift back out of OD.

My stock tune wouldn't go into OD until 40 with light throttle, not going over 2k RPM's during acceleration.



To verify this, go onto a completely flat straight road and turn on cruise control at 30MPH and see if it still does it.

 

Believe me, this has nothing to do with my foot. I've owned enough F150's to know that something's not right. My '05 didn't do it. Just wondering if anyone else has had this problem before I take it back to the dealer.

 

Do a search to see if there is a TSB for that.

Darrin

 

I am pretty sure I have the same issue as you. I also have an 08 FX4. I guess I have never paid attention to what gear I am in, but at low speeds and when I am light on the pedal, (sometimes but not always) it slips in between gears, revs up, then engages back again. I never had this issue with my 05.

 

this is exactly what my sisters explorer did, and we figured out it was the transmission. got a new one put in and that was definitely the problem.

 

It *MAY* just need a PCM reflash - hence the recommendation to research TSB's.

 

I believe I saw a TSB for something similar to this issue...

 

my 98 is doing similar to the same thing. mine feels like it goes in and out of gear while in regular drive. doesnt do it in 1,2,or overdrive. the thing that gets me on mine is that the rpms dont go up or down while this happens. but i can sure feel it and hear it in the tone of my exhaust. any ideas????

 

I found this TSB. Pretty much describes what mine is doing. I said earlier that it was doing it between 4th and overdrive but now I'm not quite so sure what gear it's doing it in. When I take it in tomorrow I'll mention this TSB to the dealer.

TSB 08-14-03

2007-2008 F-150/MARK LT BUILT BETWEEN 12/4/2006 TO 5/20/2008 ONLY - ENGINE RPM FLARE DURING 3-4 UPSHIFT UNDER LIGHT THROTTLE ONLY - 5.4L 3V / 4R75E ONLY
SOME 2007-2008 F-150 AND MARK LT VEHICLES BUILT BETWEEN 12/4/2006 TO 5/20/2008, EQUIPPED WITH A 5.4L 3V AND 4R75E, MAY EXHIBIT AN ENGINE RPM FLARE DURING LIGHT ACCELERATION DURING THE 3-4 UPSHIFT. THIS WOULD ONLY OCCUR AT ROAD SPEED RANGES FROM 25-30 MPH (40-48 KM/H). NO DTCS OR OTHER DRIVABILITY OR TRANSMISSION ISSUES WOULD BE PRESENT. REPROGRAM THE POWERTRAIN CONTROL MODULE (PCM) TO THE LATEST CALIBRATION USINGIDS RELEASE 54.5 AND HIGHER. THIS NEW CALIBRATION IS NOT INCLUDED IN THE VCM 2008.3 DVD. CALIBRATION FILES MAY ALSO BE OBTAINED AT MOTORCRAFT PARTS FOR FORD, LINCOLN OR MERCURY VEHICLES.

 

I don't know if I'd settle for that. How long has that trans. been doing that slipping, and how much wear has happened to it? Sure, they may reprogram it, and all will be fine. But how long does that tranny last now???? I'd certainly want to have a look at the fluid, and sediment in the pan...at their expense!!!

 

Just got back from the Ford dealer. Took the mechanic for a ride to let him see what it was doing. I suggested looking at the TSB posted above and thats the one they ended up with. Re-programmed the PCM. So far the truck hasn't done it again.