lack of power 7.3 PSD

[pike270]

I am getting about 12 MPG, in overdrive (automatic) it has little to no pick up and also only when it is cold out (plugged in) it blows lots of white smoke even blows some when the engine is warm. Other than that it starts fine when it is cold out (not plugged in), idles fine and makes no funny noises. If anyone has any ideas it would be appreciated.

Thanks

[pike270]

Now there is a very loud hissing noise coming out of the tail pipe, the hissing noise goes away after the truck reaches operating temperature. Does awayone have any ideas? thanks

[oldtimer550]

The hissing is normal, part of a "quick warm up" cycle.
Put a couple cans of Diesel 911 in it, and a can of injector cleaner. But drain the fuel bowl and replace the filter first.
Sounds to me you have water in the system. No power, no throttle response, white smoke are dead givaways. It will run OK, but have these symptoms..
just went through it with mine.
2 cans of 911 and ijector cleaner. Take it for a 10 mile drive and then see how it goes.

[sevenmalards]

Yep, I agree change the fuel filter and dump some cleaner in the tank.
The "hissing" when it is cold is a valve in the exhaust right behind the turbo called the "exhaust back pressure valve" and it closes when the engine is cold to warm it up faster and it will open/shut off as soon as you push on the brake pedal, try it next cold start.

[pike270]

Thanks guys, the hissing noise continues will i am driving (pushing on the fuel and brake)and it only does it between 1300 to 2000 rpms. I was wondering if that is normal.

[oldtimer550]

I think so.

[helsel_182]

it should do it until the engine get's to temp or maybe half way... unless you had a 6.0 those will hisss all the time with a turndown my buddys does it i like the sound