New tires = auto 4x4 engaging (pulsing) under hard acceleration?

[sport2000]

Hi all. I've had this problem for a while where I attempt hard acceleration between 2500-3500 RPM's and feeling a stuttering/engaging of the front wheels. I recently installed new tires, just some Goodyear stock size replacement (255/70/16's) and now it's much more noticable.

If i engage the 4x4 high and try the same hard acceleration from 2-3 or 3-4 at 3000rpm's, the problem isn't there and the car just moves. Go back to 'auto' and it's as clear as day.

I've read the 25 page thread on changing it to 2WD in auto with a switch and have been tempted to do it, now it looks like it's a necessity unless I keep my foot out of it.

any advice is appreciated, this is driving me nuts. thanks!

 

[IAmTodd]

Sounds like a wheel sensor problem(happened when mounting the tires?) or a tire defect.

 

[IZwack]

unplug the front ABS/speed sensors (located under each headlight) and go on with your bad self and them hard accelerations - see if it still shudders. If it still shudders, then its not because of the front ABS/speed sensor mama-jamma (ahah oh snap!)

 

[sport2000]

It's been doing this for years, but seems worse since I put on the new tires. It appears to be the same problem this fellow had:

http://www.explorerforum.com/forums/showthread.php?t=107256&highlight=4x4+hard+acceleration

What I meant by hard acceleration is a bit more than 1/2 gas, not floored. It completely goes away if I try this in 4x4 High. It's as if the GEM is sensing the back wheels are slipping and trying to compensate with engaging the fronts, which creates a pulsing effect. If you let off the gas a bit, it immediately stops.

 

[thewishkah]

are all 4 ties the same size? changed all at the same time? the reason I ask is the auto4x4 does not like different size tires even if they are the same size and just more worn in one set then the other. It measures wheel spin and since the tires are even a little different in size they turn at different speeds or something which makes the 4x4 think your wheels are slipping. I hope this helps you , if not maybe it will help someone else in the future. The mod I think your talking about is the brown wire mod.

 

[gijoecam]

It's been doing this for years, but seems worse since I put on the new tires. It appears to be the same problem this fellow had:

http://www.explorerforum.com/forums/showthread.php?t=107256&highlight=4x4+hard+acceleration

What I meant by hard acceleration is a bit more than 1/2 gas, not floored. It completely goes away if I try this in 4x4 High. It's as if the GEM is sensing the back wheels are slipping and trying to compensate with engaging the fronts, which creates a pulsing effect. If you let off the gas a bit, it immediately stops.

My 98 sport has done this since new. (well, until I did the brown wire mod last fall). It's always annoyed me. It was in at the dealership twice, and both times they told me it was normal. It still works when I want it to with 110k on it, so I guess I don't worry about it anymore.

-Joe