Hey guys, I found this site when I typed my truck problem into Google, and I saw so many posts that pertained to my truck. I liked what I saw, so I registered instantly. I have a 2000 Ford F150 7700 Edition (rare find) with a 5.4L motor and 3/4 ton rear end, transmission, frame, and axles. I've had it for two months now, and I've noticed some sort of vibration in the rear end while I'm driving. It occurs MOSTLY when I'm climbing a hill and my my transmission hasn't shifted to OD yet. I have Terra-Grappler 285's instead of the stock 245's, but I'm worried that my rear end or perhaps my transmission could be the problem. Any advice??

 

Are you sure that it's the rear end? A majority of the time these odd "vibrations" or "shudders" are actually a failing coil on plug pack (COP) even though gys would swear that it's something else.

Darrin

 

I don't consider myself a "motorhead", but I'm damn sure it is coming from my rear end. It's almost like it struggles shifting out of OD on its own.

 

I am definitely not saying that this is positively your problem, but I have been doing this stuff as a profession for a long time and I have been fooled by both bad COPs and EGR issues that cause bucking and 'struggling' issues. What I am saying is that you need to keep an open mind and check everything. In this case, the most common thing that causes this on these vehicles is a failing COP.

First question on your theory would be to ask what the rear end cares about a shift into any gear? Yes, the loading is different on the rear end in different gears, but what would that have to do with it feeling like it's struggling to shift out of OD?

Don't lock yourself in a box on this. I have chased my tail doing that WAY too many times. LOL

Darrin

 

Search the forum for "low grade misfire". Happy reading!

 

I just bought this same truck 2 months ago and I am having the same issue (along with a few more) did you ever sort it out?

 

Check the universal joints.

 

I grabbed the drive shaft and shook it and there was no play, is there a better way to check the u joints? put it on the computer today and the only code was system running lean

 

driveline vibration and shudder solved, u joints were toast and I replaced them yesterday. The ball joints are shot as well and that's next on the list.
The whistling or noise I hear under the hood is a broken exhaust stub, the noise drives me nuts!
I also have a couple codes now, po171 and po174

 

Exhaust leaks before the front O2's can cause lean codes. So will vacuum leaks.