Need Help Again With A Noise

[chris79bronco]

I get into my truck this morning after work (I work 10pm-7am) and I cycle the glow plugs couple times and crank it up, runs fine, let it idle about 5 minutes or so then pull off. Now about a week ago I put a 3 inch down pipe on it and a turn out, didnt put and exhaust on free flow, I love the turbo whistle!! But back to the noise, I get to about 10 mph and 1500 rpm and it the turbo whistle is gone and it sound like air just moving really fast out of the exhaust, I pull over get out and put my hand there and its normal. It does it between 1500-2500 and if I goose the pedal a little it sounds like something is sucking shut and the turbo whistle comes back. Is this that warm up flap or is my turbo going bad? Reason Im worried is because I havnt heard it till this morning and Ive done nothing different in the last week since the exhaust change. By the way its a 97 7.3

[chris79bronco]

I think it was the warm up valve, I drove it again and it wouldnt make the same noise at all. Can anybody confirm ??

[madpogue]

Kind of a woossshhhh sound? Yeah, that's the EBPV.

[chris79bronco]

Guess it just got cold enough that morning for it to kick in