When we bought our 2016 Explorer 2.3 EcoBoost last year, I couldn’t help but notice that when the engine is running, there is an unmistakable “hissing” noise coming from the engine at all times. It’s noticeable at idle, and especially when driving next to a wall, etc. if you’ve ever heard what a bad serpentine pulley bearing sounds like, picture that. I assumed that maybe it had a bad bearing on one of the pulleys. But since then, I’ve listened very closely when I’m near other vehicles with the same engine (including the 2.0 EcoBoost)… they ALL make the exact same noise. Even the naturally aspirated 2.0 liter in the Focus makes the EXACT same noise. So what am I hearing? Is it the HPFP? It’s not an issue, I’m just really curious as to what it is. I’ll try to upload a video tomorrow. FYI, it’s not from the turbo, since the NA version of this direct-injection engine makes the same noise.