For about the last year my 93 has been making a loud whistle at WOT near redline and sometimes when I lifted off the gas, recently it started making the whistle from 4500 rpm on up to redline. I'm getting a boost pattern of approximately 10-8-8, so it kind of makes sense that either something is wrong with the secondary turbo, a hose is connected wrong, or a hose is just disconnected or leaking. Any ideas on where to start debugging? I've searched around for similar threads but can't find anybody with exactly the same symptoms. A couple articles suggested that a metallic sounding 'zing' indicates a failing turbo, but FWIW this sounds more like air than metal.

Thanks for any info.

 

Also, this is definetly not the normal sounds of a turbo, so please nobody tell me how much they like the sounds of their turbos.

 

Do you have a down pipe? It could be the air pump making sounds if your pre-cat or main-cat is clogged. Check these first and work from there. If one of the cats are clogged, it would explain your unhealthy boost patterns.

 

No downpipe, its pretty much entirely stock except for a k&n filter. Are there how-to's to check the pre-cat or main-cat or will I need to take it into a dealer?