Weird siren noise 2015 Ecoboost

This noise started recently. Seems most pronounced after cold start and under light, pre-boost throttle. Clearly RPM dependent. Any idea what it could be?

Sounds like the turbos blowing off excess boost.

Can't be that. Engine is still in vacuum in both clips.

My experience is with the Ecoboost 3.5 so it may be different on the 2.3. On them there is always has some sort of boost building from just off idle to when there "is boost". Helps with no turbo lag.

I had my wife help me rev the engine, and the noise does seem to be coming from the turbo. I removed and reinstalled the UPR adapter connections at the inlet and the turbo outlet pipe but it made no difference.

So far I've checked the outlet connection, both connections for the UPR catch cav adapter at the inlet, the DV connection and assembly bolts all right and secure. I also checked the impeller for shaft play (none observed). Any other ideas?

Just the sound of turbo.

No, this is new and different.

UPDATE: The siren noise was a failing turbo bearing. After hearing the turbine blades zipping against the inside of the housing, I pulled the intake off and felt obvious radial play. Turbo replaced at 27kmi.

itguy08 said:

Sounds like the turbos blowing off excess boost.

Click to expand...

Yep, the turbo bypass valve releases excess boost when the throttle is closed. I was noticing a slight high pitch air release sound coming from the turbo area when I turned off my engine and heard it activate 5 min. later. Inside that bypass valve is a rubber valve. When the engine is off and pressure is released. The excess boost is slowly purging from this valve diaphragm. If you notice this sound increasing or you notice less boost from your turbo. Your bypass valve may need to be replaced due to wear.