01 Ford F350 Super Duty 4x4

Hi

Thanks for using FixYa. Usually its an issue with Transmission fluid & filter. I'll suggest you to get the transmission fluid and filter checked first. Next thing to do is to have the computer control module updated with the latest firmware. The dealer will call this "flashing" the computer. They should do it for free, or will charge a nominal price.

If these things are not the issue then it can be an issue with the torque converter or it may have happened that torque has locked up.

Please do accept the solution if the issue is resolved or else revert for further assistance.

Thanks
Rylee

Hi

Cam Shaft Position Sensor Faulty - extremely common on this engine and can give off intermittent symptoms under load exactly as you describe.

Given the work you have done on the truck so far thats where my money is unless you have already changed this too!!

Hope this helps. If so please do rate my answer. Many Thanks.

This could obviously be many different things. The first that I would think would have to do something with the fuel. If you have done anything to the car to fix this so far that information would be helpful. If not, I would start with changing the fuel filter and running a can of good fuel injector cleaner through a full tank of gas (I suggest Greased Lightening, which can be purchased at NAPA or O'Reilley's Auto Parts). That is what I would start with. If that doesn't fix it or you have already tried that, let me know and we will move down the line of possible culprits. Thanks for using FixYa!

Do u have a gas or diesel engine, can u please give more info on this, do u have a check engine light?

That is a good indication that your transmission needs to be serviced soon or have a transmission shop reprogram the transmission line pressure. 
I would also recommend that the transmission be flushed with the proper Mercon V transmission fluid. Here's a good Tech article on how to diy. http://www.fordtrucks.com/articles/july2002/changingatf.php
Only recommendation I have to this article would be to disconnect the line at the top of the radiator on the drivers side, rather than trying to do it at the transmission. In most cases this seems to be the problem solver.

Just another one of my personal experiences on the transmission problem...Make sure the fluid is TOTALLY removed when changing it. Make sure the fluid is removed from the torque converter. Most places simply drain the fluid. UNACCEPTABLE! Find someone who uses the complete fluid removal method by pumping in the new while simultaneously pumping out the old. If it is the shutter problem, it will solve that. Leaving the fluid in the torque converter will surely contaminate the new, without question.

Take Note: Ford specs a Mercon V ATF for 4r70w transmission and regular ATF (dex/merc III) fluid for 4r100 transmission. Putting a dex/mercon III in a 4r70w increases the chance of shudder in this particular transmission.
The 4R70W uses Mercon V, the 4R100 uses Dexron/Mercon (same as Mercon III)

Good luck and keep me posted, Be glad to answer any questions you may have. Recap, have a transmission shop do a transmission fluid flush and have them do a transmission line pressure test to ensure that transmission has the proper pressure to lock up the converter at certain engine loads.