Well, I took my two week old F-150 out for a 60 mile drive down the Blue Ridge Parkway today and this is what I've determined.

I do have a vibration as others have described. My vibration occurs between 1200 and 1400 RPM, when a load is applied to the engine (my foot pushing on the accelerator). I feel it in the steering wheel and through the floor. It was most noticable when climbing uphill between 45 to 50 mph which equates to 1200 to 1400 RPM. Downhill 1200 to 1400 RPM and speed between 50 to 55 mph the vibration was nearly non-existant.

Next, I tried uphill at 45 to 50 mph, but 2000 to 2100 RPM (behind the power curve) and the vibration disapeared. I've come to the conclusion that the vibration in my truck is engine/driveline related. The engine must not be balanced perfectly in the 1200 to 1400 RPM range, which is exaggerated when the engine is under load. Could be the driveshaft, or the transmission coming out of the back side of the engine. Who knows?

The vibration wouldn't be a big deal, but most of my driving falls in the 1200 to 1400 RPM range at about 45-50 mph. I'm taking it in for service in the next couple of weeks and I will not allow the tires to be touched. They are fine and balanced.

Does anyone know how the engine/transmission is attached to the frame? It might be too solid of a connection allowing the engine vibs to transfer into the frame which then find their way into the cab.

 

DT

I've had the same issue for months and tried to analyze the problems without success.

All furd dealers are very much aware of the 2004 F150 tendency toward vibrations but continue to clear their inventory of new trucks.

Let your dealership handle the repair, if possible. Demand a free rental car (for which furd will reimburse the dealer) then be prepared to drive the rental until your problem is 100% resolved to your satisfaction.

 

https://www.ford-trucks.com/forums/s...s+#post1691631

This sounds like the most likely thing come up with so far, a few people have solved their problem using the methods on this page of this thread, read all the posts.