Noticed this twice now, after the truck is all warmed up, when I 'get on it' lol and roll the coal...

A really small puff of white smoke hits first, then the typical 370 coal train.

Whats causing the white puff?

Truck runs great, no oil leaks, not using antifreeze.

 

Does it bog when it does it? My first guess is just too much fuel to burn when you get the white puff.

 

Mine will load up a little when its idleing to warmup. But after i hit the road it cleans right up.