Dont know what type of tranny i have but I have an 04 new body style fx4 with a 5.4 and tow package. Maybe someone could help me with that. Anyways, I pull a 4500# trailer every day and I have 95k on the odo. The truck pulls it fine and I run it in OD since it doesn't have a problem pulling. Just about a month ago, only in overdrive, it will thud once at a time while under load feeling like I'm driving over a rumble strip. If im not giving it any gas in OD its fine as soon as I give it quite a bit of gas under load in OD it will thud. It doesn't do it in any other gear only OD. If it is my tranny and have it serviced is there any upgrades to my tranny I should do that would prolong or benifit to overall health of the tranny? I though about putting a shift kit in it since I heard that mechanical shift kits are better for the tranny than making your tranny shift harder with increased line pressure with my programmer.

 

That's an engine misfire. You have one or more coils and/or spark plugs that are on the verge of failing. Getting the spark plugs out of that engine is a real treat. Ford issued a Technical Service Bulleting (TSB) that details a three day process to get the plugs out without damaging the heads.

 

Unless you have regeared it, I'd tow with OD off.

 

I know I need to change my plugs, hopefully shortly after Christmas here. I guess I will have to do that and see if that takes care of the prob. Sometimes at low rpms my engine will bounce in revs by a hundred or two, I wonder if that is to do with coils or plugs?

 

Don't just pull the plugs out. You may have to replace the heads if you do. Get the TSB and read it.

 

When was the last time you had the transmission serviced? mine did the rumble strip thing when down shifting out of OD, i pumped 31/2 qts out of the transmission and it hasn't done it since. I have since dropped the pan and replaced the filter and added 4 qts of new fluid. But just so you know, i thought i had a miss fire as well, so i replaced the plugs and it still did it after the plug change. So my advice check your transmission fluid first.

 

I had the exact same problem, had tranny flushed and it was better. Like you said, giving it a littlte gas around 55-65 mph it did the "rumble stick" effect and when getting into the gas and down shifting it would cluck and **** hard. Have tranny flushed first and go from there.

 

Hey, did you ever follow up on the tranny flush?

I just had the same thing happen to me tonight and I hopped on google and typed in "tranny feels like rumble strips", brought me right to this thread

I just bought the truck and the previous owner informed me the spark plugs were just replaced... tranny flush sound valid, just wondering if you had any luck with it.

Thanks!

 

If the truck was just tuned up you may have torque shudder. Have the fluid exchanged
with mercon v.

 

This sounds like my 95 Mark VIII when the torque converter would slip at low speeds and slow acceleration. A fluid change fixed the Mark. I'd suggest a fluid change and see if it helps.

When the TC is locked up at low speed, accelerating slowly caused the TC mech lockup to slip. This is what caused the rumble strip type vibration on my Mark.

 

Change fluid, filter and add a bottle of shudder stop. Mine does it about every 60,000 miles.

 

Some auto parts stores now sell something called "LXE", it is a transmission addittive that addresses torque convertor "shudder" which is what you are experiencing IF its not a misfire. It is a 10 oz bottle, they have a mercon-v version that is black or you can buy the platinum version that helps in almost all of them, most transmission parts distributors also stock it as almost all transmission shops use it, Smitty