looozin' boost

[dstoops]

:confused: I was pulling my 12,000 lb trailer today. When I accelerate the boost would go up to 8-9 # and immediately drop to 0. When that happened it was blowin' black smoke and had low power. If I lifted and carefully applied the accelerator I had good boost until it hit that 8-9 # again. After I unloaded the trailer the boost topped out at 5-6# and seemed to work OK. I'm suspecting the vacuum solenoid (183,000 miles on it) but am open to any other ideas. I've got about 12,000 on the R/B motor.

[C.K. Piquup]

Go with the Turbo Boost Solenoid.Then go to vacuum if TBS doesn`t do it.Check for sticky lever from vacuum or hose.Worst case:Wastegate valve stuck open.

[patrick m.]

what was the outside temp during this pull?
could be in need of a charge air cooler

[dstoops]

Ambient temps were not excessive ( 70's). I'm suspecting the vacuum wastegate actuator. I went out today to "stand and stare" at it. I can move the wastegate arm to different positions and it stays wherever I stop it. It seems to me that it should return to a certain position when I let go of it. Isn,t there a spring or something in there?
Thanks
Dean