2010 XKR,
So I failed to identify the problem initially, suspecting the garbage Dunlops to be at fault. But now with a new set of Bridgestones and fresh alignment, the vibration continues. Clearly felt through both steering wheel, and gas pedal.

This is not a continuous vibration, but best described as throbbing at about 1 to 1.5 second intervals, and noticeable only at 2250RPM.
Anything drive-train (wheel bearings or whatever) is out so now I'm looking at anything forward of the torque converter.

Anyone experienced this? If I cannot identify it soon, then it is off to the dealership, where my pocketbook will live in fear.

Thanks for any ideas....
Vince

 

Why dont you narrow it down for us some.
So if you stay in 1st gear, you get the throbbing at 2250 rpm and not above or lower right? With DCS off and sport mode engaged right?

 

Do you get that "throbbing" when stopped, in neutral, A/C off, and gas pedal depressed to maintain 2250 rpms? If so, you've ruled out suspension, steering, brakes, compressor, rear end, etc.and can focus on the engine and exhaust. Any codes? Vacuum leak?

 

Good suggestions, as I had not thought about disengaging the AC. took the car out and ran through the paces..... and am more puzzled now than ever.
You cannot distinguish the thrumming in park, but it becomes noticeable about 3rd gear, and gets progressively stronger with each higher gear. Now hee is the od part it took this drive to notice... the thrumming is at a constant rate....I climbed to 70, and had to obvious thrummmm...thrummmm.thrummm. took it to 80, and than 90 and the rate of the thrum did not seem to increase equal to the engine RPM after all. At least to my feel, it seemed to remain constant!
I downshifted to raise RPMs assuming I would find a harmonic up around the 5k area.... Instead I got the same rate thrum that I had in 3rd gear and 45 MPH.

That makes no sense to me, as I know of no component that operates at a constant RPM on a car between 45 and 90MPH.

I've got to be missing something here....

 

The noise doesn't appear till 3rd gear at 45mph? Then any speed after that, the frequency of the vibration stays the same? Also the vibration occurs even if you're in park or neutral? That being the case, must be in the engine somewhere. Interesting, never come across this before. I can check tech bulletins Monday to see if there is anything in there, but I don't recall there being any. Do you get any abnormal noises associated with the vibration? Any warnings on the dash?

 

I'd put the car up on a lift and push the exhaust pipes around to make sure they're not too close to other parts of the undercarriage or have any hangers that are loose or have worn or missing rubber isolators. Exhausts can transmit vibrations through the chassis into the front end including the steering wheel. Hopefully, that will be the cause; otherwise, I'm at a loss.

Good luck, and let us know.

Stuart

P.S. Every time I get in my XKR I feel a throbbing, too! Don't we all?

 

Thanks, a check underneath is worthy the time and energy.
As most who know me would tell you, I'm kinda a fanatic about suspensions, so now that I have had the car 3 weeks, it was past time to pull the tires and go all in on an inspection (exhaust and all). I'll be looking closely at any electric fan motors as well.

Anyhow, thanks again
V

 

Possibly engine or exhaust mounts. There was an issue on earlier models that caused a throbbing/resonance at a lower rev level 1200-1400 and there was a Jaguar fix by changing or adding an exhaust mount to the transmission.
Not sure if this was an issue on a 2010 model

I have this on my 2007 that doesn't have the 'fix' not sure if these new brackets /mounts are still available.

 

I've got that on my '07 as well... not at all the same, but thanks.

V

 

Somehow, I knew my poor choice in words would give someone an opportunity for a wise crack or too...

 

See this is why I asked you my earlier question about does it happen if you never take it out of First gear. I.e. use it in manual mode.

What you are describing is a classic bad wire or plug or other combustion problem (in my experience). The reason you notice it in 3rd gear and more in 4th is that those are the gears you would notice a miss the most. Its definitely engine.

 

Well, I'll have to ponder that part, as I'm not inclined to think combustion issues just yet. But pulling plugs for a fast inspection is always a good thing to do as well.
The 5.0 is coil-on-plug, and a misfire is easily detected by the ECU, so that and wiring is not at the top of my check first list. (There were no codes in the system.) I've not heard of any harmonic balancer issues with this motor either.

I already have plans to get the entire intake side of the heads cleaned with the BG GDI system down here at my local Ford dealership, which will give me peace of mind about any carbon buildup on the intake valves.

There is just something that has a resonant frequency under there, and it become more obvious as the engine experiences higher torque loads.
This could be as simple as engine mounts.

Wonder about the VCT system as well, but would think that would toss a code.

V

 

Good points. No the VCT wont necessarily throw codes. (based on a member's experience) Which makes my point. Seen plenty of times where bad wire will only act up under stress. But back to your point, yes the VCT or TAC is actuated by oil torque- you may be on to something.

I would not do that BG service till you find your problem, as it is not problem free. They have to run the engine while running the solvent through.

Based on other cars, the carbon problem manifests itself more on idle and rough starts.

Out of curiosity, what oil do you use and how often do you change?

 

The car itself is 3 weeks new to me, and of course no warranty left on a 2010.
I'm debating oils right now, as I need a full fluid change for peace of mind (although I bought it from a Jaguar dealership that claimed to have performed a full service prior to putting it on the lot.) I will probably look into Royal Purple as a preference if they line up with Jaguar specs.
Need to up the game on brake fluid as well with something like Motul 660.

 

Congrats. Its a keeper and sleeper.

Stick with the oil developed by Jaguar, that oil is no joke.
I asked because of the potential of buildup. But there is no way for you to know. However, seems like you want to have a perfect machine. I was able to clean mine by doing 3 oil changes back to back, about 2 months and 2000 miles apart.

 

I thought about what I would in your situation. I would do a dyno test (cheaper than dealer diagnosis) and find out how much power you have lost. That will tell you if there is a carbon buildup problem. It may also identify if your vibration is engine rpm or sympathetically resonance. Keep us posted.