Gents i am having a strange issue with my truck. It's a 2008 F150 Screw FX4. The vehicle has 59,500 miles on it. The issue is that when cruising along at approximately 26-28 mph, at basically at idle, sometimes when I "tip in to the throttle" with very little pedal, the truck acts like it is downshifting, and by that I mean going from ~1600RPM to ~2600 quickly. I have had it on the scanner and datalog when the event occurs, and neither commanded nor actual gears show up as changing (still in 4th). It really feels like either the converter is unlocking, or it is jumping a gear though. The only mods to the truck are a CAI kit and slightly larger than stock tires. I recently changed out the screen and did a tranny flush, and it had no effect on the issue. I have towed very little, and what I have towed is not very heavy, and otherwise I am pretty easy on this thing, otherwise the fuel costs alone eat me up. Anyone have any ideas? I can't believe the tranny or converter is bad at less than 60k.

 

Put it back on the scanner and datalog the torque converter clutch data. Is it unlocking the converter?

 

Will do today. I was looking for a DTC bit to set, but don't see one. I am using HP Tuners, simply because I have it for all my LS stuff.

 

What about it just coming in and out of over drive possibly being what is happening?

 

Did you flush the oil? Or simply drain the pan and replace the filter. A proper flush will do wonders for you.

 

If that is what was happening the data would show the gear changing from 4, but it didn't, so it is still in overdrive.

 

The 07-08's had some of fords worst transmission programming shifting strategies and the oversized tires aren't helping.....

 

So some news. Since the day after I have changed the fluid, the transmission no longer seems to be having a phantom downshift issue. I have been out datalogging the last few days and I have not been able to recreate the condition. So while I an happy that the issue appears fixed, I would really like to know why simply replacing the fluid which wasn't burnt, or noticeably discolered had such a positive effect, and why it took a couple of days to fix itself. Does Merc 5 have some sort of detergent package in it?

 

All ATFs have a detergent package.

 

SO I thought I had gotten lucky, but I had the issue occur twice last weekend, but I did not have the data log equipment running at that time. I think I am going to correct the speedo first (It's 1.5 mph off at 60) and see if that makes a difference. barring that, there are some parameters in the tune that I may mess around with for converter unlock strategy.

 

You may not want to hear this, but call FORD.

I had this problem very often the first 3 years I owned my truck. I brought it in for a bad heater temp control switch and the service advisor asked how it shifts at 27 mph, I told him like crap. He said there is a fix for it. FORD knew there was a problem and they would work on it.

It is MOSTLY fixed, I read about a tsb. Then I heard there was a 2nd tsb to fix it all the way.

If FORD is willing to fix it for free, I'd let them.