I'm in love with my Jag (or Miss. Money-Penny as I call her). I have been religous with maintenence. There have been bumps in the road over the years and this is one of them. I Just took it to Boston and back and it has been running fine.
On 1/20/11, as planned, I brough her in for the big 100k service to include replace belt-drive, replace spark plugs, change oil, polen filter and of course the usual inspections (major service). In addition I had them replace the air filter, BG cooling flush, brake fluid flush, steering flush, fuel filter, replaced rear stabilizer bar bushhings, 2 new tires mounted and balanced.
During the service a crack in alloy weel was discovered so had that fixed too.
I was excited to get it back, but noticed that on acceleration between 50-60 mph the car vibrated (not in the steering but the frame). Gas milage went way down 14 mpg Hmm. Didn't do that before.

Brought it back to the dealer where I had the work done and at first said it is the tires... need 2 additional new tires (even thought they have plenty of tread left). But first they did a test and used a doner car and replace all 4 tires and wheels. Road test, vibration sill there.

Prop shaft was replace 3 years ago so not likely to be that. Now they are saying transmission/ tourque converter.. Major repair!!
I'm thinking it is directly related to the service that was recently done.

They put in 2 new gaskets inlet manafold. could it be possible they did not torque them down properly and they are sucking air?
Any ideas????? Help. I have to face this Monday agian.

 

Does the car vibrate when revved sitting still? That should answer the gasket question. Makes sure you try revving all around the rpm range that corresponds with 50-60mph. Did they remove the brake rotors at all? Reset your mileage and check it again. Mileage drops whenever you let the car idle and dealers regularly push cars hard during test drives. If it really is that low, I'd have them double check everything they did under the hood. Might have developed a miss, bad plug or wire etc.

 

Thank you for your reply. The car does not vibe sitting still. They did look at the brakes rotors and said they are fine. I keep directing them back to the work they did and they keep telling me it is nothing they did. Thanks again for your reply and when we figure this all out, I will be sure to post the results.

 

It goes without saying they aren't willing to accept blame. But the fact remains the odds point to it being related to something they touched or caused while in their care. Still can't rule out an engine issue by the revving since it might only happen under a load but it would have been a nice clue if it did it sitting still. Ask them if they actually removed any rotors. Sometimes if you don't mark them and put them back on in the exact orientation (same lug to same old hole) they don't seat perfectly and will cause vibration. But there really isn't a reason to pull them unless they needed cutting or replacement.