My z28 just recently turned the big 85,000. Ive been noticing its running a little sluggish. Also my rear end howls and i get a vibratioin in the wheel from 45-51mph and a vibration in the floor at 85mph+. I'm about to get long tube headers to replace my shorties and i wanted to get a new cam and eventually get new heads built to the cam specs. Would these upgrades and say a tuning fix the sluggishness? Why is there such a loud howl, i was told my 3.73 was set up incorrectly and i had it reset but a friend and the howling quieted down but its loud again. The vibration at 85+ is probably the driveshaft right? but why from 45-51, i know its not alignment, i just had that done. I also noticed that either the car is dying for friction or something, because i can mash the pedal and the engine you can hear jump to high RPMs but the car really isn't going anywhere for like 3 seconds. Whats up with my car? would new programming from like MadZ make the car a little better?

 

Sounds like you have drive train issues. Since you don't have particulars in your signature we will assume from your comments that you have an A4.

When was the last time you did a tranny service?

If I were you, I would have a back flush service and then replace the filter. I like the back flush cause it cleans the valve body but it doesn't change the filter, it only back washes it. Also while you have the pan off, place a piece of flat ribbon type magnet in the bottom of the pan.

After that, consider having your rear done and check the axle bearings while your there. They are common for howling.

 

when someone suggests a tune up, what actually constitutes as a tune up, what does that include?