Vibration While Accelerating

[jbitzer]

Here's something interesting that was found on my '00 4.6L Expy. It one of the model that has AWD and I have been noticing vibration especially when hitting the accelerator. At constant speeds or when in cruise its fine.

I had it lifted and my mechanic and I stood under it looking for some clue. I had a trans flush in May but as my mechanic pointed out, on the AWD models it gets a little more complex (for those mechanically inclined you can skip this next section)

In AWD, the front and rear are all controlled by the transmission. This adds an extra component to the mix when it comes to pinpointing transmission noise - the transfer case. There is is transfer case just about dead center on the underside of the vehicle. When we looked at the fluid which should have been mercron red, it was motor oil black. Apparently there is a center transfer case and a front and rear differential. The transfer case is there to handle the front and rear wheels when they are being driven at different speeds. This was changed yesterday.

Monday I’m going back to have the front and rear differential fluid changed and while under the truck we found a broken seal on the passenger rear wheel which will done too.

I’ll post an update what I find after getting this work done and if this vibration is reduced or eliminated.

 

[AvroAero]

Had the problem you did. Most likely the A4WD. If you don't have a 2wd position, then the easiest fix is to get rid of the A4WD. Theres a wire for the magnetic clutch on the transfercase (its brown and strays from the wiring harness). Cut that to cut it out. In terms of fixing it, I think it has to do with wear in the driveline or a faulty speed sensor(s). It uses speed sensors in the front and rear axle to detect slipage.

If doesn't fix, you can reattach that brown wire.