I have a 2016 EcoDiesel with an AFE Air Intake and a straight pipe to the stock rear small muffler.
If you have this intake you know how loud the turbo can be and how we don't have a "blow off valve" on these turbo's. They are a variable geometry turbo so they manage the "blow off" differently then most other systems do.
In the first 5 mins of driving it after a "cold" start, or first start up of the day. When I am maybe 5-7 psi of Boost (I have a mechanical boost gauge installed) and barely am in the gas
(boarder line about to start decelerating if I let off the gas the slightest bit), it sounds like the Turbo is spitting for a split second then goes back to normal. It's almost as if the turbo doesn't know if it should build boost or let it off and stutters for a second which sounds like the turbo is "spitting" for a split second.
I know the normal sounds of the engine/turbo and am use to the way the variable geometry turbo sounds. Sometime it is almost like someone has an air compressor on at low psi and is leaking it into my vents in the cab of the truck because it is buliding boost and releasing it at the same time.
I wish I had a sound clip but the issue is intermittent and would be quite lucky to happen to have a mic ready to record.
Theories I've thought of so far:
1. Is the turbine warming up faster then the housing of the turbine so it is "seizing" up for a split second because of the expansion of the blades which is causing it not to build and/or release the pressure "seamlessly"?
2. "Does it not have enough lubrication?"
3. Is their oil leaking into the turbo? (I would think that would help it work better in a sense but it could be "spitting" the oil out causing the noise) I know some have excess oil issues with indications in their Intercooler Pipes, but I was told some oil is expected.)
4. Bad ball bearing in the turbo? (If it has one)
5. Worst Case: Engine failure/Timing Chain issue? Slippage?
Anyway I appreciate any input. You guys rock!