Piston Slap: That Ecoboost Turbocharger Whine?

Matt writes:

Hi Sajeev,

I wrote to you a few years ago regarding a water leak in the moonroof of my old 2010 Ford Fusion. I traded that car in 3 years ago on a brand new at the time 2015 Fusion Titanium with the 2.0 Ecoboost and AWD.

I have had this car for 3 years and just rolled over 100,000KM with it. My issue is that under hard acceleration from a low speed or a stop there is a whining noise that sounds like its coming from the front of the car. The whining noise sounds like the whine a supercharger makes. If i accelerate gently there is no noise and if I floor it on the highway there isn’t a noise I can hear either.

It seems to be only a low speed thing and heavy on the throttle that recreates it.

I took the car to the dealership last week while it was under warranty and they claimed it was the turbo and replaced the turbo and a number of associated parts. The car is still making the noise under the same conditions and now my warranty is done. I’ve googled the issue and been on the Ford forums and couldn’t find anything related to the noise i’m experiencing.

Any idea why my turbocharged 2.0 Ecoboost sounds like a supercharged engine?

Supercharger whine is a delicious thing, not so much when its turbocharger whine.

My initial feeling was that the source is a loose turbo plumbing somewhere between the air filter and the throttle body. That’s because higher engine loads/boost levels cause stresses in forced induction plumbing not seen at lower throttle inputs, causing the loose piece to break its “seal” with the rest of the system. Usually that leak causes performance issues, as boost flies out of the system and throws the anticipated air/fuel ratio out of whack. Not so here!

My best guess? There’s a body plug (AKA grommet) either missing or improperly installed: more likely if you put an aftermarket amplifier power wire (i.e. an old school amp, not the digital ones that are easy on power requirements) using a factory grommet to feed the wire past the firewall. It’s a long shot if you’re running a stock stereo, but still worth putting the Fusion on a lift to verify!

What say you, Best and Brightest?

[Image: Ford]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.