VGT sticking?

[majek5]

On the way home pulling my toy hauler my CTS was showing the VGT at 85%. On the trip out on Friday, the % was moving up and down like it should. On the return trip it was boosting 10psi with the % being like 85. Then it "kicked in" and went down to 40% or so and was moving up and down with the boost at 20psi. All the time, no smoke and it was running fine. Is this a sticky turbo, or maybe a bad VGT? I have a turbo rebuild kit for when I tear into the EGR delete, oil cooler, ect.

[majek5]

BBBBUUUUMMMMPPPP

[PowerstrokeTech82787]

Turbo rebuild kit?

You mean a CHRA? or new impellar and turbine, shaft, unison ring and vanes?

Id tear it apart and clean it. And pull the vgt solenoid out and inspect that. Ive had one that i did a simple cleaning on and didnt pull the vgt solenoid out to inspect where the tip rides on the cam in the housing, had it come back with a 2263. Assumed it was an exhaust leak or something nope, pulled the vgt solenoid out and the tip had a rough and deep ridge worn into it...

[dieselmac]

Yup. The PCM will continue to increase the duty cycle if it's not getting the response it thinks it should. The 85% you saw is max duty cycle. Once the turbo breaks free, you'll see the duty cycle fall off and boost pick up.

[majek5]

I didn't check for codes, but sounds like the turbo needs a good cleaning. It ran fine on the way down, but it sat for 2 days in the rain. Maybe the moisture was enough to freeze it up.