Greg_8507

I know this probably sounds too simple, but i have actually seen this on my parents explorer. My stepdad ignored the airfilter a little too long and it started whistling just like you described, when you give it gas it gets louder. Changed the filter, it stoped.

72404F150

Idratherbedriving,
I was searching for the whistle today and had a little luck. With the combination of my tuner a & the cold weather, my truck has been running a little cooler than it should. I don't know if any of this applies to your stiuation. To the point, I opened my coolant reservior cap to find that it had a significant vacuum in it. After the vacuum was relieved I could no longer duplicate the noise. Still not sure why the coolant resevior was pulling a vacuum. Some how I dont think this is over yet.72404F150

Idratherbediving

I suck at this! Thank God for mechanics, I might have to visit one soon just to keep my sanity. After I finally bought a large enough wrench I tried to remove my EGR valve. I couldn't get the large exhaust nut (compression nut) off, even after I tried a few Finlander tricks.

In a few days I'm going to be working a guy who does car work as a side job (he was a mechanic for a number of years). I plan on picking his brain about my truck.

More about my problem: It was gone for a week and now it's back again. It sounds like it's coming from midline just behind the firewall. It's not loud most of the time. The loudest it's gotten would be, what I would call, a loud whisper.

It might take a little while but I'll keep you updated.

Idratherbediving

Well, he told me that he usually has to tourch the nut to remove it. Or I can remove and replace the exhaust manifold with the EGR valve. So a little whistle noise suddenly doesn't sound so bad. Good luck with your problems.