right after i start it and let it idle for 30 seconds the exhaust makes a poping sound and smokes white why is this? straight piped

 

Is it doing this while idling or when you throttle it up, failing injector maybe.

 

What you're describing points to a leaking injector as autocar56 said. White smoke when the motor is cold almost always means too much fuel (if the white smoke continues after the motor warms up then you should look into a blown head gasket). If after the engine warms up the color of smoke changes form white to gray or black then you can narrow the problem down to fuel/injector.

 

it only does it right after i start it up and rev it.

 

Well you def shouldnt rev it up right after a cold start. Starting it up and gunning it imediatley down the road could blow your head gasket. Let it warm up a minute. I like to wait till coolant temp is up before i get a heavy foot

 

Diesels can be cranky until they warm up. Some of my equipment on cold days will darken the earth. As said above, its not good to crank on a cold motor. Until the cyl temp comes up to normal some times you will get popping and smoke when getting after a motor thats not ready to burn the fuel.

 

I take the route that has stop signs to the highway to go to work. When I'm at a light and it's cold, I'll hold the brake and give it a little throttle, not much, the little extra load warms it up quicker.

And yeah, don't give it much of any throttle til the temp starts to register on the gauge.