My 99 F150, 5.4L has developed what I think everyone refers to as shudder. First, it started when I would release the accelerator occasionally while running about 45 mph (1200-1300 rpm), I would feel a clunk or two like a bad u-joint. Now, it has started what feels like a slight constant surge at the same speed while traveling on a level road without any load on the motor. It goes away while accelerating or going up an incline.
This what I've done so far:
1. I checked the driveshaft while in neutral with the parking brake down but everything felt tight.
2. I added a quart of Lucas with no results.
3. Next, I changed the fluid and filter and drained the torque converter. It had the gray mud on the magnet but no significant shavings.
4. I added a tube of Shudder Fix, drove for about 8 miles and it hasn't helped.

By the way, the transmission has 139,000 miles on it. I know the fluid was changed at 105,000 but not sure if any before that. The truck has been use for towing a 20' bass boat for a good bit of its life.

Do you guys think this could be a bad torque converter or something more serious?

 

I have a similar problem, in fact my symptoms are almost identical. I cant tell yet if its the roads near me or a wheel joint going out. I really hope its not a wheel joint.

 

Anybody else had this problem???

 

You sure it's not a low grade engine misfire? How old are the plugs and what kind are they? Have you ever changed any of the COP's?

 

Sounds like a stuck valve body, try adding some lucus trans treatment and see if it clears up

 

I have changed 3 of the COP's and the plugs at 100,000. Normally when my COP's have gone out, I've had the misfires at an idle all thru the acceleration range. I added the Lucas when this began but it didn't help any.

 

What did you use for plugs and cops?

 

I think I used Bosch plugs. I'm not sure on the COP's.

 

I would check the truck for codes. Had almost identical problem at work on the Dodge parts van. There would be a bang when it went in OD then a shudder until you gave it enough gas and came out of OD. You only feel it when the torque convertor locks. It ended up being a misfire, bad plug on cylinder number eight.

 

Bosch plugs have a reputation for not working right in the modular Ford V8's. I would pull them out and put a set of OEM Motorcrafts in. If the cops are getting weak, I'd put a whole set in from Global on Ebay, they are under $100 for all 8. Make sure you use plenty of dielectric grease.

 

I agree with the surging could be a misfire but what about the clunk I feel when I release the accelerator? It feels like a bad u-joint but I've checked and they are tight. Sometimes it's a pretty harse clunk or two.

 

My check engine light hasn't come on. Doesn't it just come on if there is a code?? I think I'll order the COP's from global and see what happens. That beats pulling the TC.

 

Get rid of the Bosch plugs while you're at it.

Too many reports of them causing problems exactly like yours..

Steve

 

I agree I’ve heard the Bosch plugs aren’t the best for Modulars not only on this site.

You might want to see if there are any codes in history. If you have a code in history your light wont be on. Just to see if there was a detectable misfire at one point in time. It might be able to point you in the right direction.

 

I have had this problem before all you need to do is change the trans fuild and don't forget the change it in the tourqe converter also,.. and this will fix it. but if you don't change the fuild in the tourqe converter also, it will not fix it. Hope this help..