My mother has 2016 Escape with the Ecoboost package in it. The other day she said it started to whistle but it only does it for a few seconds at start up. Drives perfect and the sound is not present while driving or idling other than right after start up. The sound starts as a soft whistle but gets a little louder until it goes away after about 5 seconds or and you never here it again till after the engine cools a bit and you restart it. If you start it and turn it off and back on it will only do it the first time its started till after it sits for a while. Any ideas what I could start looking into as a cause? Something in the boost part? I am all most positive it's not a belt slipping, really doesn't sound like that. When she first told me about it my first thought was a belt but after hearing it a couple of time I just don't think so.

It is a 2016 Ford Escape with the Ecoboost package... Sorry for the incorrect subject line

 

Sometimes a loose hose clamp between the turbo and the intake will produce a whistle when throttle is depressed. Quick and easy to check all clamps for being tight.