About every 3rd time I go somewhere, the car is very shaky especially at lower speeds around 0-45. You can see the steering wheel shake. Like I am driving on cobblestones. Other times it drives normally. Any idea what this could be? I am compiling a list for the dealer to look at and this is on it but would be nice to have some knowledge if this is a known issue.

 

JagGate, the wobble in the steering wheel is most likely due to picking up a pebble or something in the tread and that is throwing the tire(s) out of balance. My car had a little wobble in the steering wheel when I first got it, but after a new set of tires and having the tires road force balanced, the wobble is all gone.

If you ever need someone to help you with a project on your car, let me know. I am south of you down in California, MD.

 

If it's not caused by what Thermo said, there could be many other causes involving wheels, tires, and suspension components. Did you buy your XJ new or used? How many miles on it now? Let's rule out the easy stuff first.
Check the tire pressures when cold with a digital tire pressure gauge and confirm that they correspond to the tire pressure specs on the label on the driver's door jamb.

If you don't drive your XJ every day, sitting in one place for more than 3 or 4 days can produce a temporary flat spot on each tire that can cause the steering wheel to wobble until the tires warm up and become round again.

Bent rim? Separated radial tire belt? Hitting a pothole can easily damage a tire and rim Have each wheel/tire checked on a spin balance machine for runout and high spots, and inspect each tire for sidewall damage, inside and outside.

Check the front suspension for looseness and damaged bushings, particularly if over 40,000 miles.

Let us know when you determine the cause.

 

Car has 15k miles. The big puzzle is that it is intermittent. I drive every day and never know what to expect. I just got back from a 20 mile trip with no issues. This morning it was vibrating. And the speed is odd it will shake the wheel at 25mph. This is very unusual. I think I read somewhere that the cars have active motor mounts. Maybe that system is having issues? Car is still under warranty btw.

 

While the motor mounts are fluid filled they are not active as in system connected to either electrical or hydraulic systems. While I am no longer in the engineering world since retiring, I'd be looking at the transmission/differentials drive train system. Could the front differential be culprit? Not sure of anything here just MHO.

 

Thanks all. I am going to have all 4 wheels rebalanced and maybe an alignment to ensure there are no mechanical issues. The wheels/tires are brand-new but had to have the TPMS swapped from the previous set and although they said they balanced them I am actually not sure they did. I am still confused about the low speed vibration since an imbalance issue typically would not cause this at low speeds even if it was badly out of balance. Nothing in the tire treads btw. Also the problem seems to be getting better as I drive on these new tires. Perhaps they just needed to wear in a bit.

 

Interestingly, this problem seems to be sorting itself out. It has been getting smoother and smoother the more I drive. The car had only 12k miles on it when I got it and I think those were extra-babied miles. I have been driving more spirited and especially taking turns and curves a but tighter. I think the suspension might be breaking in somewhat. ECO still doesn't work at all but I think I will just replace the battery for that.

 

" I think the suspension might be breaking in somewhat...."

Glad to hear that .
My suspension is breaking down somewhat.