Racer944

Hi folks;

Need some help/thoughts... I have a 2011 FX4 Screw Ecoboost with about 70K miles on it. Recently when under normal acceleration I now get a loud sound until I get to cruise speed or let off the gas. It can best be described as a fog horn sound or very similar to the sound you get when blowing over the lip of an empty beer bottle. It is a constant sound that does not vary in tone with RPM and does not seem to be drive line related but more engine/intake/turbo related in my opinion. It does not happen under very light acceleration, disappears as you get to cruise speed (or let off the gas), and to me does not sound mechanical (no grinding, clicking, banging, rattling sounds).

Ford has had my truck for two weeks now and cant figure it out... they changed the 4 wheel drive actuators/valves even though there was no grinding sound or clicking sound of any kind, and also apparently changed one of the manifolds and some vacuum lines... All this work did nothing at all to change or get rid of the sound...

The truck is out of warranty, so I have spent a small fortune on what Ford dealer thought (erroneously) might be the problems, but I cant let them keep guessing and changing stuff. I am still in shock that they changed a bunch of 4 wheel drive components to the tune of $1K (when I had no issues with the 4WD system) and then gave the truck back to me with the exact same problem...

Anybody have any thoughts or ideas of where to go from here to try to diagnose this?

Thanks;
Eric
Ontario, Canada

RRfisher

I can't help, but only offer my 2014 FX4 Ecoboost does the exact same thing and I have chose to ignore it, especially now.

antony1103

I'm taking a WAG here...

Not sure if its the same with the Ecoboost, but the 5.0 intake tubing has helmholtz resonators on it to reduce engine noise. You'll know you have them if you see a dead-end tube branching off of the main tube going from the filter box to the throttle body. These tubes work exactly like you described, the air going to the engine blows over the openings to these resonators like blowing over a bottle. Their size is tuned to produce a noise that is out-of-phase with the engine noise and works to cancel out the sound and make it quieter. Adding a CAA effectively deletes these resonators, which is why you get that throaty intake sound.

I imagine if something like water or debris gets past your intake filter and into the resonator, you change their tuning which could lead to noise, sort of like changing the pitch when you blow over a bottle by filling it with water. A quick check would be to remove your intake piping and try and force anything out. Its worth a shot. Its free and should only take like 10 minutes...

maplelakeduckslayer

Buddy has complained of a similar noise on his '14, bov? His would be on his intercooler though, I've offered to pull it for him and see if it has any tears, he isn't very mechanical. I just pulled mine on my '11 and checked them, pretty easy to do if you wanted to

Racer944

Thanks for the input guys! I will check the intake as suggested. I have also ordered a set of BOV's ($80.00 so not a big risk) and intend to pop them on myself this weekend to see if that may be the issue (I certainly hope so)... Will report back.

Cheers;
Eric

maplelakeduckslayer

They factory or aftermarket? Brand? Don't think I've seen any that cheap wanted to do mine, they aren't torn but wondering if my springs may be weak

Racer944

They are factory FORD parts (CL3Z-9U465-A). Mine is a 2011, so I needed a pair of them. As far as price, I am located in Canada, but I have seen them from Ford Dealers online in the US for $27-$30 each.

Its a full kit with valve/spring/seal/bolts/instructions. I just hope this resolves my issue.

Cheers;
Eric

maplelakeduckslayer

Thanks! I haven't been able to find that specific part

Racer944

Issue resolved!

I replaced both BOV's on the weekend (relatively easy job, took the wheel off to make access easier). Passenger one was fine, but drivers side had a good sized tear in the rubber valve/seal.

Solved the problem completely, noise is gone. Ford dealer very surprised when I showed them the issue. Apparently not a common problem, so hope this helps someone in the future.

Cheers;
Eric

maplelakeduckslayer

Great job, had a feeling that could be it. Thanks for the part number, Mine aren't torn but curious if the springs are weak, will probably order a couple up