Got my '06 Duramax at 178k miles and have 197k on it now. I bought it with the P0299 and P003A codes (turbo underboost and vane position not learned) after being told by a few shops that most likely it just needed to be cleaned since the truck ran so damn good. 20k miles later, finally got the chance to put it in the shop for a cleaning...
Long story short, cleaning didn't work.. Shop pulled the turbo, found a broken unison ring and frozen up solid vanes. Even they couldn't understand why the truck ran so good. The thing was putting out full boost, and hauled [censored]. It's beyond me how it ran like it did with these things messed up. Shop told me whoever owned the truck before (it was an older guy) grandpa drove it, and after time all that gunk and carbon built up in there and caused the damage. Told me the best thing to do is every now and then run the [censored] out of it and blow all that stuff out of there
Had them order a stock reman turbo. 1 year warranty. Also did an EGR delete, and they put some kind of EFI Live tune in it to keep the MIL off due to the EGR delete. All in all, even though I'm out a few dollars, I'm extremely happy. Will be ready tomorrow.
The craziest thing.. Stopped in today to just check the progress. Truck was ready to roll, just waiting for their tune to come in so they could put it in the truck.. I went back there to it and started it up, and it sounded different than what it used to for sure. Had a real deep throaty sound to it. Didn't realize a new turbo would change the way it sounded. Sounds good now!
Here's a pic of the unison ring and turbo