You are correct. The dpf is there to remove ALL black smoke. White smoke is raw hydrocarbons (fuel). Ever see a semi fire up in really cold weather? It will puke white smoke until the engine is warm enough to burn all the fuel that is being injected. The same theory is true when a regen is initiated. When the DOC is too cold to burn all that is being injected into it, the unburnt fuel escapes as white smoke.

 

So while I agree with you that some white smoke may be normal, what also happens is the engine bogs down, and sometimes it seems the transmission isn't finding the right gear. I'm unclear in seeing how a cold DOC would impact engine power like this. Also, it happens after the engine is well warmed up, like hours of driving.

BTW as reported if you back off the throttle, it fixes itself, but I've also tried hitting the throttle harder to see what happens and often times that too will seems to fix it. It's almost like the transimssion finds the right gear, the engine RPMs hop up, and voila, no more smoke.

Any thoughts on how this can be?

 

Yup. You are correct. The majority of my driving is local intown.