I have a Stock 02 f350 7.3 with 66,000 miles ... I'm sure this has been covered plenty if times, but I notice more so on cold days (-20 to 30). My truck after starting and even letting it warm up for a period of time makes a hissing sound from the passenger side of the cab near the dash/glove box area, Like I said I've only really noticed it on cold days ... It usually occurs between 1200 and 1800 rpm and it's a very touchy noise, for example I only really hear it when I'm cruising at a consistent speed, if I get on the gas a little it goes away till I bring it back to consistent throttle cruising then it comes back, same goes for when I let off the gas it goes away until I give it a steady consistent throttle again .... Any help is appreciated! THANKS !!!

 

That is your Exhaust Back Pressure Valve and tuning doing precisely what they were engineered to do. Driving a cold engine is rough on the hardware, so the engineers came up with a "flash-heat" plan to get that block up to a wamer temperature right-quick. Your toes will appreciate the effort as well.

When cold, the EBPV closes, building about 15 PSI added backpressure to the exhaust. This brings your Exhaust Gas Temperature up from 500-600 degrees F to about 800 degrees F while driving on the highway. If you're fast-idling with the EBPV on, it raises the EGTs from about 300-400 degrees to 400-500 degrees. It also introduces more load on the engine, which brings the Engine Oil Temperature up faster than without the EBPV. If you really need the power, pressing the accelerator releases the EBPV, and you have a clear path for your exhaust. This is akin to clearing the truck's throat before a yell.

 

I've heard about the EBPV and that seems to be the logical explanation ... But how long is it suppose to stay on for becuase like yesturday, It's was -7 with the wind chill and I started the truck and let it warm up for about 15 minutes becuase I wanted to just get out of work and get home, on top of that 15 minute warm up the truck was driven at least a half hour and stayed at idle for another 15 minutes at a stop I had to make, the EBPV stayed on when driven that whole time... I would think that the EBPV would turn itself off after a while

 

Like Rich said above. However: If your ebpv tube is compromised (hole/rust/clogged etc.) or your sensor is plugged with soot it can act up when it shouldn't be.

A hole will render it inoperable one way and clogging will push it the other way. I can't recall which way is which, stuck on or off?!

I have an E99 and am in northern Michigan. My truck does exactly the same thing yours does since temps dumped into the teens. One of our friends here just reminded me that until the oil temp sensor reads 132 F it is triggered to stay on.

I'm thinking I layed that out right.

If it gets to the point you want to disable it for any reason. Reach left and down of the turbo ped and you will see a plug that has a metal bail. Drop the bail and gingerly unplug it. Bag it for cleanliness at future use. It won't hurt to drive it like this but rest assured, your warmup time will increase drastically.

Denny

 

THANKS for the help it's much appreciated

 

Mine makes that noise. It occurs when the engine isn't working hard in cold temps. The EBPV closes to keep the engine warmer. It opens as soon as load on the motor increases a little. Guys who have an aftermarket intake will complain of the noise being louder.

 

It may be my tuning, but mine shuts off just as it crosses 140 degrees EOT, and I wonder if air temperature plays a role.

 

You may want to get a scan gauge and monitor EOT,EBP and see what's going on I had stated in a previous thread that mine would stay on until EOT was 120 - 130 but I was wrong and it is staying on until about 145. I have also noticed that it is taking a while of driving for my EOT to reach 180 or above in 15* to 30* weather. I also know of one 7.3 that the butterfly stuck on the EBPV and burned up #8 cylinder.