I have a 2006 f350 6.0L turbo. I got a under boost trouble code. I'm running 15w40 right now and the temp. where i live is -28C and I'm having boost issues. I'm not getting full boost pressure. I was driving down the road at 90kmh and lost boost pressure. For the past couple of months I've noticed that when ideling the turbo wistle would com and go. I was told that was normal cause the turbo gets up to a temp. then cools down.
I don't seem to have any leaks or boost tubes loose. I'm not sure how the variable vane works but I'm wondering if the oil is too thick for the winter temp and is not allowing the vanes to function right. I should also say that i have some boost pressure but not enough. I don't seem to have the boost when i'm half on the pedal, but when i floor it it seem to get more boost. The wistle when ideling is very quiet not as loud as it use to be. I have a 4inch exhaust and you can notice when the turbo is spooling.


Pls help.

 

The turbo whistle coming and going is in the programming of the truck. It's being commanded to "exercise" the vanes in the turbo to keep them from sticking but it sounds like they are sticking anyway. Have you possibly checked it for codes?? There is a repair/cleaning procedure for the turbo in the tech section at the beginning of the forum. You might try taking the truck out and running it pretty hard for a bit to clear out the carbon. it does help sometimes.

 

i got the p0299 i think. the underboost code.
i've done some reading and see the the EP sensor has been an issue and cause the issues that i am having. or it might also be the hydrolic valuve for the vanes.

 

Err, what?

First check you MAP hose and the nipple that the hose plugs into on the intake manifold. then look for cracked CAC couplers, then if all else fails, try the VGT relearn and finally pull an clean your turbo.