sometimes when i start the car i here a whining noise. also it occurs when turning sometimes. anyone know what this is?

 

it could be your steering pump or your alternator.

 

Is it front, L/R, behind? Windows open? GF/Mother? Oops, sorry! Are you turning the steering wheel when you hear it? Check the steering pump fluid level. (See BangNgears). Or through the Stereo? Does it whine in proportion to the rpm? Check your battery voltage/fluids.

Also, check to see if your alternator is under a Nissan recall campaign.