scab05

Hello all and Happy New Year!

I'll start by writing that there are a lot of posts about this problem, and reading through them I find that I am more confused about where to start spending money, so I am reaching out to you guys for help.

I have a 2005 F150 screw, 5.4l 2WD 4r75e trans with 75K miles on the original drive train and I have not changed the trans fluid. I have used this truck to tow, and over the last year close to max tow rating as determined by ford specs and certified scale weights. I have an edge tuner set on #2 towing program, and I am able to see what the trans is doing and where the shuddering/bucking is happening.

While driving between 40-50 mph under light load (as read by the % load on the edge) the trans shifts into 4th gear and the torque converter will lock cleanly and quietly. If I go up a hill and gradually put pressure on the gas pedal, as soon as the load gets to 80% the truck starts shuddering like it is rapidly shifting, and if I hold it there, it will continue until I back off the throttle, or the torque converter unlocks (the lock icon on the edge turns off) and it will smooth out again. I can replicate this while towing my travel trailer in 3rd gear with OD locked out and the TC locked, but it is much quicker to unlock than when in 4th gear.

The stall speed of the TC is 2000 RPM (give or take) as read on the edge programmer and the dash tach. When I check the stall speed, there is a slight miss at WOT under full brake

I changed the plugs and COP's one and a half years ago when I put new phasers/tensioners/timing chain using Motocraft plugs and summit racing COP's. I have re-flashed to stock settings with no improvement.

Normally, I would start by changing the trans fluid and putting in new Mercon V, but I haven't found a method yet to get all the fluid out and I'm do not trust the dealer. I'm sure there are good ones, but none that I can find.

Thanks guys and I'm hoping for some insight here.

FStorm150

I recently had the same exact problem. Took it to Ford for diagnosis, determined the clutch in the torque converter was not engaging/disengaging properly when shifting out of overdrive. Options were to replace the torque converter, or try a tranny flush and adding some friction additive to try and get the clutch to loosen up. I took the cheaper option first since I had not changed the trans fluid up to that point (122K miles) because I did not want to spend the money on a new torque converter. Just had new plugs and boots put in not too long before that as well, so it wasn't a power/misfire issue, as determined by their computer. Sure enough, all it needed was new fluid and the friction additive and it's good as new. No hesitation, no jerk when shifting out of overdrive. I would try that first, it being your cheapest option, and go from there.

jamie930

I also had the same problem BUT when I changed the plugs I did not change the COP boots and springs.
Changed the COP boots and springs the shutter/ miss went away.

The new springs were about a 1/4" longer than the old ones.

A complete sets of springs and boots can be had from Rock Auto for around $30 shipped to you

scab05

The problem is fixed. I did a full fluid change with filter on the trans, as I needed to do it anyway. Found the issue was a broken COP (cracked where the connector goes into the COP body). Thanks for the feedback