Volvo Repair: 2000 Volvo S40 SMOKE BOMB, combustion chambers, 2000 volvo s40

Question
questions about my 2000 volvo s40... i just had a engine put in it cause the other one broke.  well i got it back yesterday and today it started smoking when i was at red light. kinda light but then it turned into a pretty good smoke ball at idle.... so i parked thinking WTF... well few hours later i take off and its seeming fine then 5min.. while im driving i can a good amout of smoke tailing me, and when i stopped it was a cloud.. i just got this engine put in has a great deep sound to it and excelertes awsome...i just dont get it.... what else could cause my great looking volvo be a smoke bomb...

Answer
Thick white smoke indicates coolaant leak into combustion chambers like head gasket.
Bluish smoke is oil burning, rings or valve seals and guides.....Or check the flame trap first, maybe it wasn't replaced and is clogged.
Black smoke is overly rich mixture. Need fuel system checked out