The difference in the part number means there was a revision. It's not actually a different turbo. Typically there will be no way to tell the difference between an "A" part and a later revision with a visual inspection.
Well turbo number two is down with 6k more on the clock. I have drove another 4k while having the issue. It is not that the turbo its self is making a noise as thought before. The turbo is venting boost to the exhaust pipe when ever I get in it 3/4 or more. It has something to do with the control solenoid as I can make the truck have the issue and while still rolling down the highway, put the truck in Neutral and turn the key off, then restart and all is good till I get in the gas hard again.
Any ideas?
The 2015 turbos do not use a wastegate. Therefore there is no way for the turbocharger to "vent boost" to the exhaust. All exhaust gasses must pass through the exhaust turbine.
In order to regulate boost pressure, a VGT (Variable Geometry Turbo) system is used. The solenoid you are referencing moves a set of vanes within the turbo to effectively vary the size of the exhaust turbine housing. If the vanes become stuck closed, you will have severe turbo lag with a lack of power at low RPM. If the vanes become stuck open, you will have normal power at low RPM and a loss of power with excessive boost pressure at high RPM.
From what you describe, it sounds like the vanes became stuck closed, causing a loss of power and excessive boost at high RPM. The excessive boost will cause the PCM to enter derate mode, which will cut power. The vanes sticking has been known to be caused by low quality engine oil. The recommendation is to use full synthetic 5W-40 oil to prevent VGT solenoid issues. The "B" part may have been released with revisions to the VGT vanes to prevent sticking.
