Wierd Vibration

[xTOM153x]

I have a 2003 Explorer 4x4 4.0L engine. I am getting a weird vibration and grinding sound when I accelerate. It sounds like the vibration/grinding is coming from the back but I can't tell because the entire truck is vibrating/grinding like crazy. On a paved road when I accelerate you would think the road is extremely rough and rocky. When i take my foot off the pedal all the vibration/grinding stops. I can cruise when not using the pedal but once i accelerate just a tiny bit it starts vibrating/grinding like crazy. I have also been getting around 8 mpg mainly city but some highway and that is down from my usual 12.5 that i was getting consistently for months. Other than this new vibration/grinding the truck drives and runs fine. I'm not sure what this could be this time but I am ready to sell this truck. I have put so much money I have put into it and I am continually having problems with it.

 

[BigRondo]

I have merged your 2 threads. If you let me know what post you want to keep, I can delete the other one.

Good luck getting it sorted.

Please keep us posted as feedback helps others reading this post looking for a fix to the same or similar issue!

 

[xTOM153x]

I would like the first post I made deleted. Thank You

I have merged your 2 threads. If you let me know what post you want to keep, I can delete the other one.

Good luck getting it sorted.

Please keep us posted as feedback helps others reading this post looking for a fix to the same or similar issue!

 

[BigRondo]

I would like the first post I made deleted. Thank You

Done!

 

[xTOM153x]

Turned out my driver side cv shaft was bad. I replaced that but now I am getting the vibration at around 45mph+ but it is not as extreme. Before I got the vibration while flooring it. The vibration still stops when you take your foot off the gas. I took a look at the rear u-joints and they seem to be fine there isn't any play in them. I'm confused at what else this could be. Anyone have any thoughts/ideas?

 

[xTOM153x]

I am' still experiencing a vibration under acceleration that can be lightly felt in the steering wheel and a lot in cab/seats. The vibration immediately goes away once you let off the gas. The weirdest thing about this is if you put it into 4x4 high while you are accelerating on the highway the vibration will be significantly less and almost nonexistent. I just want to point out I have the brown wire mod so I don't think it is trying to engage the 4x4 while I am accelerating and on top of that I have removed both fuses one time to rule out the transfer case. Since having noticed the vibration I have replaced a driver side CV joint due it having serious up/down play and my U-Joints for the rear driveshaft both of which I do not think contributed to the problem but I thought I would mention it. Anyone have any idea what this could be?

 

[xTOM153x]

Just to keep this thread updated it turned out to be the transfer case. I can't believe i didn't realize it....there is a lot of slack in the driveline and a lot of up and down play at the flange that goes into the transfer case. Once I have everything replaced will post results. This was diagnoses by a certified 20 year Ford technician he knew exactly what was wrong as soon as he drove it.