My 2001 XK8 (53k miles) has developed a vibration/shudder @~1400rpm 40-50 mph while going up slight grades. Took it to local independent repair (probably mistake) who put it on rack and couldn't find anything loose. Mysteriously began intermittently displaying abs/traction control fail warning after I recovered it from their other "Lawn Art" after three days. Was not displaying previously. They said abs control module needed replacement and they could send it out for repair for $600 plus labor. Appears tech disconnected OEM ABS electrical connection and broke plastic connector. Used zip tie to keep in place.
Back home now!
Any thoughts on the vibration cause? Any possible connection to abs/traction system?
Seems like it might be in drivetrain to me. Thanks in advance

 

I have had cars (not jag) with this shudder/vib at speeds like that. Fixes have been a change of fluid and a filter with some type of friction additive. I know I have read around here that could be the fix for a Jag also.

 

Are you talking about transmission fluid/ filter?
Thought XK8 didn't require tranny fluid/filter changes.
Did replace differential fluid with additive - didn't help.

 

Yea I was talking trans fluid and filter. Many car makers companies have sold transmissions as "LIFETIME" units which is BS. In my travels here since 08 most folks agree that it does NOT hurt to change out the fluids/filter.
But you did do the trick to fix this so it must be something else obviously.

 

I had a similar problem with a BMW 635. Turned out to be a drive shaft. I swear I don't know how that could have been the case though. I removed and thoroughly inspected the old driveshaft, couplings, U.J.s, bearings, etc. It all looked fine, and I put it back on the car. Vibrations continued. After checking out every other possible cause, I gave-in and replaced the driveshaft. Poof. Vibrations gone; never to return. I don't know why.

Moral: If, after exploring all other simpler (and cheaper) possible options, you still haven't nailed down the cause - try your drive shaft. (Have Coventry issued magic wand handy).

 

Hey Bud, key is vibration worsens up grade. I would expect you have ruled out an engine miss. Sounds to me like it is drive shaft or axle vibration.
Thanks to a member on this site, I found out about the grease fittings on all 4 rear axle "u"joints. Lubed just today . This is a service often overlooked as most late model vehicles have lube for life joints. While you lube these joints, this will not only take care of maintenance, it will indicate if you have a worn joint as you will see movement in the joint if it is bad. May just need the lube job. Good luck , RIch

 

Reb 1999 - tech at shop stated they serviced circ fittings when they replaced diff oil, but ....
Not sure if they checked for any loseness in U joints. Think they were focused on selling me an ABS module
I too sense the issue is in the drive train somewhere - no engine misfires (thankfully)
Still wondering if traction control or ABS system could be somehow be at the root of the rattling but doesn't seem to fit scenario
Thanks again

 

I have a 99 XK8 which after running brilliantly last year was awakened from a long winter sleep with restricted performance and a check engine light. After warming, the restricted performance light went off and I thought I was golden. I had a fairly long trip ahead and went up to the highway. When I hit highway speeds, the car shuddered and refused to accelerate past 100 kph. I went on the old highway with no problem but no high speed either. Th car has been at the dealer for a week and while they suspect something in fuel delivery, they still do not know what is wrong. It runs great at lower speeds.Their head tech and service manager are now on it. I really hope they resolve it. I love my car.

 

Hi - just for the record...the Jaguar position on the "sealed for life" transmission is bogus. Just check out the many dozens of threads over the years on this forum and it will confirm what I say.

Another member spoke with a tech from ZF who told him that regular ATF (auto transmission fluid) changes were essential to keep the transmission in good shape.

This may not help with you judder issue...but mine has just done a similar thing which turns out to be a sticking brake caliper..just a thought. Check if you're getting a hot brake disc (and smell)..and possibly one set of pads wearing thinner than the other.

 

My issue is related to the restricted performance - something which uneven wear on brake pads will not generate. I had thought it might be related to transmission too but the car will accelerate hard at lower speeds but will not go over 100 kph period - an out of balance wheel or a serious transmission problem will not do these things - a car with an out of balance wheel will go faster but with greater shuddering - I can't go faster and do have restricted performance. A tranny issue is possible but not likely according to the dealer. It should shudder at lower speed and higher rpms but doesn't. The check engine light is always on too. I am betting it is simple - maybe vacuum, maybe throttle body, maybe injection. It has been at the dealer a week now and they have fixed a dozen very minor things on the way to no solution to my problem. I would think with the might of the Jag organization behind them, they will figure this out. I will not abandon the car...

 

and thanks for the atf tip. I will have the fluid changed.

 

The typical cause for vibrations at certain speeds is out of balance wheels. I had a very difficult process to correct an out of balance problem, finally requiring the wheel be balanced by hand on the car by a specialist. This was the problem, a normal wheel balancer would not work. This is on the BBS Detroit wheels. It is very unlikely that the driveshaft is bent. A bad U-joint in the rear halfshaft could cause a vibration but it would be all over the place, not at a certain speed. Get the wheels balanced on the car and go on from there.

 

My issue - now not resolved with new plugs - is still related in some way to restricted performance and check engine messages showing on the dash. An out of balance wheel will not cause those messages. I wish it was that simple. I have had the car at the largest Jag dealer in Canada for over a week and am told the actual service manager has his head currently under the hood because I must leave Vancouver on the first ferry tomorrow morning. So far the dealer is stumped...

 

Due to medical appointments I had to either take my car - after eight days at the dealer - or arrange a rental. It turns out no rentals are available in time to help me get to where I need to be. My car ran easily well enough to cross down Vancouver Island and run around the lower mainland for a few days. Today, my lovely old car barely made it from the dealer to where I am staying. I am afraid I may have hurt the engine just getting here. The dealer has worked on my car for 50 hours and made it much worse. They think it might be suffering from difficulty with catalytic blowback pressure - whatever the hell that might be. All I know is that after all those hours and a new set of plugs, the old girl is done. Her next trip will be under tow...

 

Hope you can find a shop/person(s) that REALLY understands how car systems work. "Our" cars don't monitor the systems as well as newer cars and can point a flat-rater to a problem. My brother get cars from all sorts of local shops/dealers that they can't diagnose/fix/worth their time, so they just send it to "doc". My guess is there is someone like my brother in every area and works in the back ground in support of dealers and private shops, in your case "that dealer" you dealt with screwed someone like my brother and they won't deal with them anymore. My brother has his list.