All the sudden my truck makes a different than normal whistling noise when I coast down hills. I can give it a little gas and it still makes the wooshing noise, along with what feels like less power. When I give it 3/4 gas and above it closes somthing and stops the air leak sound. Its like the BOV is staying open way too long. Does this sound right?

 

no blow off valve on our trucks. you're hearing the exhaust back pressure valve (EBPV) closing. its essentially a butterfly vavle located just past the turbine housing on the turbo. it closes when the engine's cold to help assist warmup. it opens under hard accelleration or when the engine reaches operating temp. if you'd like, it can be disconnected and will stay open all of the time. someone here will chime in with you can do that if you would like.

 

Thanks

So my engine could still have been in warm-up mode? I let it sit for 5 mins idle then drove another 5 miles in 34º weather. I guess it still wasn't warmed up enough...

 

Nope, mine will stay on for quite a while even after i warm the truck at idle for about 10-15 minutes. I'll have to time it one day to give ya a better idea. all in all, the engine very well may have been in warmup mode. The EBPV's have been known to stick due to a buildup of soot, but if that was the case, you would have a constant loss of power no matter how long you ran it or how hard you put your foot into it.

 

-30c here in canada after a 45 mile trip and 20 minutes of warm up, it'll still close once in a while when I pull into the city and pull away from a red light, I live with it.

 

cool thanks everyone, I'll wait till it gets cold outside again and go from there. Might not really be needed in IN weather.