I have a 1997 7.3 with 140000 miles. I had differnt enging in it the the wastegate was welded shut. With the new engine i have no bottom end power. I was told that a code would have been sent to the computer telling it there was two much boost that would shut horsepower down by 50 or more horsepower? Should i get the computer flashed and reprogramed? The fuel pressure under load is about 56pds. And there are new pick ups in the tanks. What i can see is when the truck is firdt started the wastegate will close for 5 seconds then re-open. Is this normal for the wastegate.

 

These trucks do not have a wastegate and they do not have in tank pumps. That's good fuel pressure.

 

The wastegate probably isn't working correctly because there isn't one on your truck.

Kidding aside, you're referring to the EBPV (exhaust back pressure) valve.

It's supposed to close in colder weather to aid the truck in warming up and then re-open. You can literally just unplug it if it's acting up with no harm at all on the truck.

Just make sure it's not stuck half closed before you unplug it.