'02 F-150 7700 Super Cab, 5.4 auto with towing pkg. 107,000 miles... a lot of towing a boat and a travel trailer. Approx 1 year ago (89,000) was getting a rumble noise taking off from a stop. Took it local Ford and they flushed - rumble gone. Next, (March '08) was getting a "flapping" sound from the rear end. Back to local Ford and a new rear end (~ $2000.00). Now, at around 45 - 55 mph there is a jerking - almost like a manual trans when you need to downshift. Except this is an automatic and it's "at speed". If I accel, or take it out of OD, it subsides. Also, it seems to do it only after it has been driven a while, 20 miles or more. Especially on the interstate. Nothing when its "cold".
Went again to the local Ford and they said they couldn't find anything.
Grrrrrr.
I've got a long towing trip coming up. Suggestions?

 

sounds like a torque convertor shutter to me

 

Yeah sounds like TC Shudder.

Typically at light load at about 45-55mph depending on gearing. If you accelerate or decelerate it goes away. Not so sure about jerking, usually it feels a bit like those rumble strips on the road or a road that is pebbly.

It is the TC lockup clutch slipping, thats why it stops when you get out of OD. As the condition gets worse it will start to shift harshly on occasion and do it more frequently as time goes on.

Sometimes a fluid change will fix it, sometimes some snake oil, but in the long run you may need a new TC or a rebuild on the tranny.

If it is the lockup slipping, it just gets worse and the cost of repair increases over time.

Usually it will throw a code and tell you the pump pressure has increased. A decent tranny shop should be able to diagnose it.

Good Luck,

Jim Henderson

 

My local NAPA store keeps "shutter guard" an additive that you add to your trans fluid, fixed the shake in my Marquis!

 

it does sounds like the TC for sure.
you been towing in OD?

ive used tranX, or transX(something like that) with good results.

 

Well... My F-150 is back and of course they couldn't make it act up. They ended up putting the computer on while they drove (I suppose) and it apparently put out a code that said cylinder #4 was "dumping". So, they replaced the coil pack, at just under $300.

We'll see! Thanks for the help... hopefully that will take care of this particular problem.

 

my '97 f-150 has been doing the same thing. It threw a misfire #8 code during one episode. I've been meaning to change plugs & wires & tried the lube guard additive & the shudder has almost gone . It hasn't thrown any codes since I reset it but does idle with a slight shake. I was wondering how yours is running.

 

So far so good. BUT I've only been driving 5-6 miles a day since the fix. On Friday, I'll be going doing ~500 miles so I'll get back to you.
I also found out that I have a left front wheel bearing on it's way out. Hopefully it'll hold together a little while longer. It's always something.