Hello i have a touring 06 Z AT. I had this issue earlier when i had around 29k miles on the car. The sound would come around 3500 rpms only when cars at 75-90 mph it was kinda faint but definitely audible sound coming from the car. I took it to the stealership and first of all nobody would ride with me in the car because they claimed its illegal to speed more than 70 mph i was pissed but eventually 1 tech agreed to ride with me only to say " i couldn't hear it" well i was advised to wait and let it become more pronounced so they could diagnose it. ..... oh well i ignored it just made the music louder at 75 -80 mph.. recently i noticed the sound returned again at 3500 rpms when i am speeding from a stand still. its a very shrill sound audible around 3500 rpms at every gear right b4 the AT shifts in to next gear. What should i do do u think i'll be covered in power train warranty because now i have 40 k miles.

 

so it doesnt make the sound when the car is sittin still and you rev up the car. Have you tried reving up the car to bout 3500 rpms when its sitting still or is it just when the tranmisson is shifting gears. Just trying to eliminate some of the possiblites.

 

maybe its your airbox. even the stock ones make a high pitched whistling/ shrieking sound sometimes

 

thats what i was thinking also

 

it does it ... and more louder with intake/cai

 

Okay so i tried to repeat that sound, this time driving in trip tronic mode it only makes that sound in 2nd gear when i am accelerating from 3k rpm to 4k rpm at speeds about 38 mph. some times it makes that sound in 1st gear too at same rpm but not always. i think it might be my transmission. is my transmission covered in power train? Thank you.

 

bump

 

yes your transmission should be in your power train warranty. You just need to first convice the stealership that there is something wrong with your car. Goodluck

 

So for the first time i started driving my 350 more aggressively in manual mode to test out my transmission revving the engine past 4500 rpm for every gear change, that sound is produced in 1st and 2nd gear and the shift to the 3rd gear is very rough jerking the car every time i shift in to 3rd gear at high rpms. Do you think that entitles to a bad transmission please give me suggestions for making up a case for the dealership appointment. Thank you so much.

 

check black vacuum line to plenum for pinches/bends.

 

I'll do that thankyou.. What about the rough shift to 3rd gear is that normal for an automatic?