7.3 powerstroke help!!

My 99 f350 just recently started making a hissing sound under part throttle it goes away when I give it throttle and let completely off. Driving it down the road it sounds like it's coming from the dash... what could it be. Thanks for any help on this

vacuum leak does your heat/ac controls work right

Exhaust backpressure valve, normal in cooler weather. Mine has been deleted

69F100 wrote:vacuum leak does your heat/ac controls work right

All the controls are working great as they should

richter69 wrote:Exhaust backpressure valve, normal in cooler weather. Mine has been deleted

I thought about the EBPV when I first heard it but even when the truck was up to temp it still made the noise only at around 1500-1700 rpm holding it consistent.

How do I delete the EBPV and will it hurt anything

As long as the outside temps are cold it will still do it, unplug it to verify

richter69 wrote:As long as the outside temps are cold it will still do it, unplug it to verify

Ok thanks I will do that this evening

Or the EBPV sensor tube from the exhaust manifold to the sensor could be clogged too. Fabio would know for sure. I know I had to clean mine once before because it was causing problems.

Delete it. Its a pain in the ass when it seizes closed at some point..LOL....I would check the up pipes too, they can his if they are leaking at the turbo collector.

Well I think found the problem the small tube has rust holes in it

How do you delete the EBPV ???
My truck started nocking going up big hill towing trailer. Runs fine around town and no hills.
I just took off the cat. converter, it was not plugged, you could see through it.