2000 Expy XLT Vibration issue

[juan214]

No Problem

 

[RunningonExpy]

I realize this has been a long time coming....although I had explained before that doing the brown wire mod took care of my hesitation on acceleration problem, I still had an ongoing vibration problem, particularly at 40+ mph. Just this afternoon, after consulting with some mechanics (and getting some bad advice) I decided to get under my expedition and remove the front drive shaft. I had quite the time figuring out the right sockets and angles to do it (had to take the running board/step off first, then a cross-member from under the transfer case) but after 4 hours I finally got it out and.....guess what?

The u-joint at the transfer case was loose and messed up! The front u-joints still looked solid, but I had a sneaky suspicion that because I had the hesitation that it wasn't from the COP's (like it has been observed countless times before) that something was up with the drivetrain instead of the engine. Driving without the front driveshaft....NO MORE VIBRATION! No hesitation on acceleration and smooth driving! YAY!!!

I think my hesitation was based on the A4WD feeling some type of torque inbalance that was causing the system to reduce power to the front hub, based upon the broken u-joint not able to handle the added power in A4WD on heavy acceleration. It seems that the Auto 4WD system will automatically try to compensate by reducing power to the front hub when it feels that the driveshaft is not responding correctly (slippage), which causes the hesitation/bucking reminiscent of the COP problem.

If after replacing your plugs and COP's you still have hesitation/bucking on acceleration, CHECK YOUR FRONT U-JOINTS! I hope this info helps someone down the road!

I will post a follow-up when I get the driveshaft u-joints fixed and have a qualified mechanic install it again. If the vibration returns then it might be something else. I'll also rewire A4WD to pre-brown wire mod status to see if I still get the bucking from before. May be awhile before I can afford it but STAY TUNED!!!

THANKS EVERYONE FOR YOUR GREAT ADVICE!

 

[Yupster Dog]

My bet is drive train. Perhaps drive shaft or u joints.

Thank you RunningonExpy for coming back and letting us know.

Big winner of the day on post #3 Machete!
You have won a great prize! You get to go into a two topic conversation with Tobyu and 16plati to discuss why you should always follow manufactures recommendations and bonus topic why the 4th gen are far superior to the 2016's

Enjoy

Trainmaster for seconding the u-joints on post #5 (along with great tips) you win the moderator position on the conversation

 

[Bilsto]

Glad you solved a vibration problem. They can be very maddening. After 2+ years, I solved one on my 2000 Eddie Bauer (2WD) that was giving me fits. I'm glad it's gone.

 

[RunningonExpy]

One more follow-up to this thread...got the front driveshaft u-joints fixed and put the driveshaft back in...no vibration in 2wd or 4wd! I haven't undone the brown wire mod yet, but I'm going to put a simple on/off switch in parallel on the brown wire to see if A4WD will work without the hesitation/hiccups that was happening before. I'll keep everyone posted if that goes away once I return to complete stock.

 

[Trainmaster]

I found on my 2000 greasing the rear driveshaft slip spline joint helps clear up a bucking/thud on acceleration. Ford has a silicone grease that works very well on this. I'd do mine every five years or so after the factory Teflon wore off the splines.

 

[RonB1964]

My transfer case was behaving similar. I changed the fluid with Motorcraft Transfer Case fluid multiple times every 60k miles which helped greatly reduce the vibration. Dirty fluid or regular ATF can make it slip and cause chatter. My expy has 296k now.

 

[Robert williamson]

Once you pull the fuse to your 4x4 the motor has no power, harmless, have you checked the fluid in your transfer case?

 

[studabaker]

I like the transmission braking that is an advantage of 4wd. I would have the front drive line balanced. Those bucking engine issues can impact u joints and cv axles. If your lucky front diff is ok. The rear side of front drive line is kinda hard to get to. Use 12 in or 18 in extensions an 12 pt 12 mm socket. Those drive lines and cv axles are pretty easy to remove. I put the booted side back. Im pretty sure thats right. I never had issue with replacing exactly to marked flange as long as i got it balanced with new ujoints. Ball joints are hard to get to in my opinion but good to have fresh when the engine or other bucking is resolved...