Concur with Jerry..

white smoke coming out the tail pipe is a bad thing.

check to see if the white smoke is water vapor > take a kleen-ex and hold it in the exhaust gases > if it disenigrates >it's water vapor and probablly means that you have a blown head gasget = which is a case where the structural integrity of the coolant system [coolant kept in coolant passages] has been violated and the coolant is now mixed with the gas/air and oil lubrication systems >> not good...