On three different mornings, my 2000 f-350, sounded like it's hissing on passenger side underhood. Happens when under slight acceleration, but loses power when held at that speed. If I speed up, it runs fine. Also, runs fine after a few miles and is warmed up. Only noticed when ambient temp is below 50 degrees. One morning it was 43 degrees outside, cranked truck to warm it up, and noticed hissing sounded as if it was coming out tailpipe also. Revved engine and let it idle again and sound was gone. It has the Superchip programmer installled. Also, noticed that it smokes when first started about half the time. Whitish smoke sometime worse than others. Any ideas?

 

There should be a sticky about this. It's that time of the year again, cold engine operation. That is normal, and it is a device called the Exhaust Backpressure Valve that closes when the oil temperature is below 140*, to help heat up the engine. It is a valve that closes off about 90% of the exhaust flow, and creates a power loss and a hissing noise in the exhaust, again in the right side. It is normal, either deal with it, or unplug the connector below the turbo in front, down center of the intake.

 

we need a seasonal cold weather sticky, from about Oct 1-March 1. Put GPR and glow plug diagnosis, EBP/EBPV issues, Batteries and Block Heater issues all in there.

If it works the post count would be cut in half and probably the new winter members as well.

 

This one??
https://www.ford-trucks.com/forums/4...ke-thread.html

 

All very common and should be expected when temp start getting cold. When I had an EBPV I could massed the throttle to the floor and it would kick out of the warm up cycle.