exhust whissle
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Mountain Pass
Joined: Aug 2006
Posts: 106
Likes: 0
exhust whissle
I did the napa aircleaner & straight piped my exhust on my 2003 f-350 7.3 mileage went to 13.3 thats GREAT for a dulley but when I start on cold morning and itstarts to go to fast idle it has a sharp whissle out of tailpipe if I kick it off of fast idle it go's away. could I be having trouble with wastegate?
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
yep, that is normal operation. it is the Exhaust Backpressure valve closing. it is a butterfly valve in the exhaust that restricts about 95% of the flow. the exhaust is forced through the small area that is not closed off, thus the hissing noise. this design holds the heat in the engine, allowing for faster warmups. it was hard to hear with a stock exhaust, that is how restrictive they are. once you open it up, you hear everything.
