Just took a trip.. car showing symptoms.. what is wrong?
 

Just made my usual trip from Davis, Ca to San Francisco, about 62 miles, and averaged about 75mph. I started to feel a light shudder/throb from the accelerator pedal, and it would stay at a constant when crusing anywhere in between 70-85mph. The steering wheel starts to vibrate as well. The shudder/throb goes away at speeds above 85mph, and under 70mph. It seems to have been a slowly developing symptom, but its become more and more noticable.

Wheels were just aligned, tires rotated and balanced. The car does need engine and transmission mounts, and if thats not the cause of the shudder, could it be a worn flex disc? The shudder also occurs when accelerating from low speeds to high speeds, as you would on freeway on ramps and the like.

Other than that the car runs extremely well, transmission shift at proper times and power levels, and shifts are nearly seamless. Engine has ample power, and i run redline 85+ every other tank.(car has exhibited this symptom before while running a treated tank, so i dont think its a fuel delivery problem if that could be a cause for the shudder anyways. Low oil leakage, and no blue smoke. Other than this VERY annoying shudder/throb, the car is a champ in every way!

Whats the problem with my baby??

BTW, I would have used the search, but it hasnt been working for me since the new forum format was introduced. Sorry if im posting an inquiry that has been answered a million times.

Veloce300DT,

Try an examination of the engine mounts. The right side engine mount is more heavily loaded under acceleration, and if it is losing resiliency it will begin to act like a sound or vibration "short" instead of doing its job of attenuating these vibrations. Good luck, Jim

Thanks!

If you feel the shudder through the steering wheel, please check your steering stabilizer. Cheap and easy. Better check your flex disks and center driveshaft bearing support. too

I had near similar experience and found my center shaft bearing totally shot. The center shaft bearing is hidden from view as it is behind an aluminum heat shield. I used a flashlight and with one eyeball could just see it.

The rubber surround of the bearing was torn up and allowed the whole drive shaft to wobble and was more noticable at around 60 mph.

You have to remove the exhust system to gain access.

This may sound strange but I had a similar problem and found out it was the air filter mount! It was a very light shudder that only occured at certain speeds. After jacking the car and crawling around under there numerous times also. I guess it was because of the location of the break and a smooth idle that it threw me for a loop!