I recently deleted my 16 f-250 and installed PPEI tuner and 5” straight pipe. I’ve noticed that every now and then at an idle it makes a hissing noise for about 15 seconds and goes away. Is this normal and has anyone else noticed it? And It sounds like a turbine when I put my foot in it.

 

It's normal. I believe it's the turbo vanes adjusting.

You were expecting to hear the turbo after deleting, correct?

 

Sounds like turbo whine. I haven't deleted mine, planning on it this weekend. But 4" instead of 5".

When the engine is warm and you rev, you should hear turbo whine. Is that the same, or similar, to what you're describing?

 

yes , but just sitting in traffic with the windows down and all of a sudden it just hisses for a few seconds after sitting for say 5 minutes or so

 

That's how it's supposed to sound.

 

I didn't know (or don't remember) the new turbo's having that strategy. I know the original VGT on the 2011 job 1 spool up and spool down twice after idling for around 20 seconds.
For example, mine (since new) after coming to a stop and >20 seconds pass by, it spools up, spools down, spools up, then has one final spool down that is much more noticeable (big sigh of relief as I call it when people ask what it's doing).
It does this in a drive through for example. However, the first spool is about two seconds and the second one is five seconds for what I'm describing.

For WOT, that's how it's supposed to sound because the air can pass through more efficiently now.

 

Nothing to worry about, that sound is normal.

 

Thanks for the replies... I was kinda thinking maybe I screwed up.

 

 

40,000 plus on delete, no black smoke even when under load. That is very important to me.

 

It will hiss for 15 seconds or so at intervals as the vanes turn on and off( or twist or whatever the description is). the exhaust does have a muffler and is very quiet in the cab

 

I appreciate Ford defines that small resonator on the factory exhaust tips section a muffler. When I grew tired of feeding many $100 bills to select components on my truck and still breaking down, I was concerned about the noise. It's noticeable under normal acceleration but not as bad as I had worried. WOT is another story though, I actually spend less time at WOT around town and homes now because of it.