Heres the story

2006 f150 fx4
44k miles on it

Flushed trans at 44k with amsoil synthetic replaced filter as well

Went on a long drive down to texas hauling 2 motorcycles in the bed. Did awesome on way down. We then headed to a place 3 hours way and on that trip was doing about 70 mph and had to pass someone so just like all transmissions it downshifts and we take off like normal- well when we finally got back to 75 mph crusing speed and O/D kicks in the truck starts to shake violently and feels like a flat tire- so we immediately pull over. I check under the truck and everything seems fine- not leaking from what i can tell. So we start the truck back up and continue on our way- the truck drives fine. a week later we start our way back home- 900 mile trip and it was fine the whole way.

Then after were home a week later i go pick up some dirt bikes - on the way there (truck is empty at this time) im going about 75 mph and all of sudden truck starts shaking violently- well this time i can try to play around to see what it does. So i hit the O/D button to off and the shaking goes away immediately- i hit the O/D button again and the shaking comes back. Well i kept it out of O/D until we got to our destination. When on the way home it was fine. So it seems like it will reset itself once truck has been turned on and off.

I also have a evolution programmer with a PHP tune in it. I have heard about torque converter shudder but have no clue what causes it or a fix.

Can anyone help me out?

 

Return the tune to stock and see if it still does it.

 

i will try that and see what happens.

 

torque converter shudder happens when the friction modifiers in the tranny fluid wear out. you fix it by getting new fluid. this isn't the only cause of TC shidder but it's the most common.

 

i just replaced all the fluid in it within the last 2k miles with full synthetic fluid?

 

Then it's tune-related or the converter itself is shot, or it's not a shudder but a misfire.

 

but if it was a misfire it would still do it when i hit the O/D switch

Im leaning towards tune or converter shot. What happens when a converter goes out completely?

 

most of the times the trans will go with it. if i were you i'd save some money now just in case.

 

i have a warranty that should cover this for 250 deductible. but it seems very intermittent so i guess ill wait till it gets worse.

 

....and then you had the problem with the TC. The first thing I would question is the fluid that you used and/ or the procedure that you used to change all the fluid. Seems very obvious.

 

i had the problem once before the fluid was changed but it ended up being the tune last time- so i got a different tune and it has been fine.

fluid was flushed by hand and amsoil synthetic fluid.

i hate intermittent problems.. i wish it would just fail and then i can fix the problem. I just dont want to go into the shop and they say nope everything is fine.

 

Did you replace the trans screen/ filter assembly and clean the pan and magnet? If the filter is partially (or better) blocked you will have a problem. If you didn't change the filter yet, I would suggest that as your next course.

 

when i did the trans flush i replaced the filter and the magnet.

the other day i started the truck and pulled out of the subdivison and the truck was shaking from 10mph all the way to 50mph - felt like no power and finally fixed itself about 3 min down the road. i wouldnt think the trans would do this- this was probably a misfire or the tune. So now i know it doesnt even out of O/D - so next step is go back to stock tune now.