Hi Fellows:

I have had a great ride with my Allroad 2002 6speed chipped APR. For the last 30k miles, the car has been smooth as silk and very quick. Now, I experience some vibration when accelerating (in fact mode or chipped) between 2800rpm and 4000rpm and my accessories rattle. Car has now 92k. New timing belt has not changed anything, the car is smooth in cruise ride. Performance not noticeably different. Could it be:
a weak engine mount?
an unbalanced shaft?
poor mix - turbo issue?
weaken seal in manifold?
other?

Please let me know if you have experienced this and what you've tried to resolve. Help greatly appreciated. Thanks

 

I had a similar experience after replacing my worn CV halfshaft on passengers side A4, 83k miles. I know there are vast differences in these two models. But the vibration you are describing is exactly what I experienced. The new halfshaft was a remanuf. and was installed to replace the worn outer CV joint and split boot, figured I'd just replace the whole halfshaft. Well whatever slight bur or machining imperfection was left in the new/remanuf outer joint caused vibration when accelerating up to speed, from the 3-5k rpm range, most noticeable when kicking down into passing gear.

Put the old halfshaft back on and the vibration went away. Just did this yesterday, now it's to the dealer for a factory spec halfshaft!

Course start with the cheap stuff, wheels balanced, engine mount check, tune up check, transmission check. But I'll be willing to bet at 90K miles you half a worn drive shaft, CV joint, or U joint.

 

Thanks for the tip. My mechanic is suspecting something like that. Also told me to wait and let it go worse for more accurate diagnosis before replacing a shaft.

 

I have a similar problem, although mine would also vibrate at cruise speed. One delaer told me all my tires were out of round... but he could sell me a new set to fix the problem. I didn't take that advise. Second dealer told me the tires needed rebalancing. When rebalancing, second dealer also found I had a slightly bent rear wheel (slightly). After rebalancing almost all of the noticible problem was gone. I have been looking for a replacement rim (probably new to avoide a bad wheel). If this does not fix it I look into the shaft thing.

By the way, the dealer remarked something about under load (accelleration) the out of balance tires become much more noticible in the vibrations. Accellerating or climbing hills on the highway are where I noticed it most.

jf