Possible tranny problems?

[JhnZ33]

Hello all, new member.

I have a 99 Ranger XLT 4.0 w / 5 speed auto trans.

A few weeks ago, I noticed a weird thump like a been bumped from the rear type noise/feeling, and it scared the hell out of me. Since then it’s been happening sporadically, so I started to pay attention to the conditions surrounding the problem.

At first I thought it might be an engine electrical problem as it had all the symptoms of one, especially happening so dam quick. I did have a “check engine” light come on and found out with a scanner it was a “slow” O2 sensor problem. I replaced the O2 sensor, but still have the problem.

I tracked the conditions more closely, and found it happened when the engine RPM was low (1500 - 2000 RPM), and while the tranny was in OD.

Now this thump/bump will only happen if I keep my foot on the gas pedal, like it’s trying to downshift but doesn’t, then finally will. If I take my foot off the gas, then push the pedal again, it downshifts and maintains speed with no thump.


Any ideas?

 

[BrooklynBay]

Welcome to this Forum! I think you have a bad U joint in the rear. As for the CEL codes, what code # is it showing after you replaced your O2 sensor? Did you replace only one sensor, or all of them?

 

[JhnZ33]

I'm curious as to why a bad U-joint would be the culprit.

As far as the o2 sensor, I only replaced the one that was giving the trouble code (and that was a chore in itself!), which was bank 1 (driver side). No codes are listed by the scanner presently.

 

[BrooklynBay]

A bad U joint could cause a vibration that travels along the drivetrain everytime you tap on the accelerator pedal. When they first start to go bad, they may squeek a little bit. After a period of time, they will start to develop play. When this happens, you should replace them before they finally give out completely.