Vehicle: 1999 F250 Super Duty XLT 5.4L V8
Kilometers : Over 303,000 Kms
Previous Work: Last Year Tire Rods and drag link were replaced
This past January the Hubs, Bearings and Ujoints that are on the front axle were all replaced.

Problem:

When trying to cruise at anywhere between 1500 RPM and 1900 RPM the whole truck seems to vibrate but can mostly be felt in the seats and sometimes the steering wheel. When given more throttle or let off, the vibration goes away. the speed ranges from doing 50 km/h (which is the speed limit in my town) to 70-80 km/h on highway (which is the speed limit out to my yard) its starting to get really annoying and has had me wondering what could possibly cause this vibration. The truck used to be an oilfield EMT vehicle and that's why it has such high mileage on it. I plan on moving in the fall but with this vibration, i don't trust the truck making the 13 hour drive. Any help on what it could be or what i could try to narrow down what the problem is would be greatly appreciated. Thanks in advanced to anyone that can help.

 

Sounds similar to what I just dealt with. It would vibrate everytime it went into overdrive. I thought my torque converter was going out and took it to the dealership. It ended up being one of the Coil Over Plugs going out. After they replaced it the vibration was totally gone.

 

When you took yours to the dealership did they have codes that came up for it? I'd rather not take it to the dealership to find out as they are charging an arm and a leg right now with the way our economy is in my area. I have access to a scanner.

 

It's not ignition, because increasing throttle in the same gear (important) makes it go away.

I want to suggest that you put it in low gear and cruise at 1500 to 1900 rpm and convince yourself that it's not vibrating. If that works, then you've ruled out the engine entirely and about all you're left with is the driveline, wheels and tires. If it vibrates, then you've narrowed it down to the engine.

About 99% of the time, when a vehicle shakes, it's a tire. Even if the tires are balanced, that doesn't make them round. If they're round, it doesn't make them balanced.

 

Not sure if it threw a code or not. It's a pretty regular problem. Look at this thread:

https://www.ford-trucks.com/forums/1...und-40mph.html