Ford DI 4-cylinder engine “hissing” noise - they all do it?

[Klutch9]

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.

 

[ctechbob]

The HPFP and injectors usually are just loud ticking noises. Never heard a hiss.

 

[Whimsey]

We have a 2017 2.3 EcoBoost and the engine is "noisier" when you're outside of the vehicle, especially with the hood up. But I never hear a hissing noise, maybe the timing chain and HPFP and injectors. But inside the vehicle with the hood closed it's relatively quiet.

 

[meep]

Does it have a properly installed air filter?

does it have any evidence of a vacuum leak?

loud hiss is not normal. The high pressure fuel pump can clatter a bit like a diesel (or I think that’s what it is), and even regular fuel injectors can get pretty tappity. But hissing to me sounds like vacuum.

 

[SureshR]

I’d check the turbo / intercooler and intake manifold hoses for any air leaks

 

[dumkid]

Some throttle body designs can hiss slightly.
Not sure on the echo boost though

 

[eljefino]

Some throttle body designs can hiss slightly.
Not sure on the echo boost though

Take the air intake hose off and you'll notice that many hiss a lot. The intakes are designed to mitigate this obnoxious noise.