Hey i drive a 91 si with a 92 zc swaped in, a few months ago i started hearing squealing i thought it was my air box. it was tottaly throttle resposive(the squeal).
i didnt have the time to really look into it but i just checked and its coming from the TB/IM. Ive been told the idle adjustment screw might be in to tight, but i havent messed with it since i swaped the motor 8 months ago.

any info would be greatly appreciated.

Lucas

 

I had this same noise after my mpfi swap. As far as I have read on H-T it is coming from the idle screw. You can lessen the noise by unscrewing the screw but this of course will raise your idle. I was thinking about taking off the TB and changing the hole that lets in air behing the idle adjust screw but I haven't gotten around to it yet.

 

I have that problem as we speak, it's my intake manifold gasket try while the car is running spray some brake parts cleaner at the inatke manifold gasket and it should stop. This noise will only go away for a day or two.

 

not much then ehh?