Originally Posted by hpcbmw
Wife' 06 LGT is bone stock and just hit 100k miles. Car is usually driven pretty mildly by my wife. The other day it started having a weird sound- high pitched squeal starting at 3000 rpm. Not as high pitched as an old school belt squeal. Only squeals when accelerating, but will keep squealing as long as I keep my foot in it.
At first I thought it was an air leak somewhere in the intake, but then I realized that the squeal seems to start right when I feel the turbo kick in.
Does it sound like a squealing mini-elephant? Or more of a metallic screech?
If metallic, stop driving it ASAP, and inspect the turbo. Change the oil and check for metallic shimmer. If there are issues, it's time to replace the turbo and hope for the best...
If you've got the elephant noizes, it's probably just a boost leak. Check the top-mount intercooler hoses/connections/clamps, namely the funky shaped one under the TMIC that goes into the throttle body. Chances are, it's blown out or worked itself loose. Now is a good opportunity to upgrade your intercooler, or at least replace the hoses to ensure you've got a nicely sealed up system.