2015 turbo whistle noise, and revs hesitation/drops - looses power. no codes

Hello all,
a symptom I have not experienced before, having had 5 Expeditons since 1997. Usually a spark plug or a coil related problems, minor problems.
Mine has no codes, driven it hooked up to a pro computer, nothing.

It hesitates and turbo whistles, intermittently, when I accelerate slowly, under tourque mostly.
Less when I downshift and floor it.
annoying to say the least.
REvs drop as much as a 1000, and car shakes a little.
most likely something to do with the air intake or intakes to turbo?
whistle sound, does that mean it´s after the turbo?
Any help appreciated.
thank you.

Daddi Bjarnason
Reykjavik
Iceland

Not on my Expedition, but on my previous 2021 Ranger I had a similar power loss and sound. Dealer traced it back to the factory blow-off valve that went bad. Stayed open not allowing boost to build up.
May be different on your Expy but something to look at. Also could be something as simple as a loose or bad hose in the turbo/intake system.

Stuck waste gate would come to my mind.

‘17 here. Had whistling noise, found out some of the exhaust manifold bolts were rusted and broken. Similar to the issue with the 5.4 issue with bolts rusting and breaking, except on these (3.5 ecoboost) oem manifolds do not use all of the bolt holes available on the heads. WTH Ford! I understand ford has updated the manifolds to use all head/manifold holes. I don’t know, I went with BD Diesel manifolds, direct replacement with all the hardware, gaskets, spacers, etc. I had both sides done at once. Ford diagnosed the whistle and quotes dumb money. When the engine is under torque it causes the manifold to separate ever so slightly to produce the whistle.
The shop also identified the large turbo (driver side and opposite the bad manifold gasket/bolts) so they replaced that as well.
Fortunately the turbo and some other work was covered by a 3rd party extended warranty, the manifolds were not.

I replaced a set of 5.4 manifolds in my driveway on 01 F150 and that was bad enough. With the turbos on this thing, I was happy to pay the shop (a reputable diesel shop who was also familiar with the 3.5 eco). Place/space/time all factored in for me.
Check them exhaust bolts, I bet some are broken, rusted and or missing.
Good luck

I will add, this was at 168,000-ish miles,
The timing chain tensioner was extended fully (no adjustments left), I also paid to have them replace the timing chain, cam phasers (with updated design) while there were addressing a warranty covered timing/water pump cover that was leaking oil. I still dropped $3k for the work that wasn’t covered (noted above) but I expect and hope to get another 100K miles out of this thing, or as close as possible.

Once the timing chain tensioner rules out of adjustment it’s a mater of time until it through codes. Misfires/timing issues, etc. Having bought used and not knowing the full history, I choose to play the long game.

Again, good luck.

Thank you all,
hope it´s not as bad as possibly the manifold bolts and sh,,
This 15 Expy only has about 45.000 miles on it?
Bought it slightly damaged and it had sat for almost 4 years, possibly some valves corroded or something.

I´m gonna start by looking at the blow off, and waste gate valves and will let you know.

And my other 15 expy drove great until I sold it at 150.000 3 years ago and still does. no problems, just replace the plugs regularly and coils whenever needed. As with all these Expies

thank you,
Daddi Bjarnason

I don't know about the whistle, but the 3rd gen had bad throttle sensors. There is a TSB about it.