It depends on how bad the smoke is. If the vehicle doesn't run, it could be a blown head gasket or a cracked head.
the smoke that comes out of a exhaust pipe is supposed to be white
Black smoke means the engine consumes too much gas - possible problem with fuel injection.
What colour smoke?
Could be worn or damaged valve seals.
black smoke means your burning oil and the head gasket will go sometime soon
Check the O2 sensor located on the exhaust pipe on the passenger side. Could be giving the computer wrong information.
Could be a diesel? If not then replace your oxygen sensor on your exhaust. A bad oxygen sensor causes the exhaust smoke to be dark in color.
In a 1999 Mustang V6, a large white awful smoke coming from the exhaust could indicate no problem at all on a cooler day. If it is excessive after the car has warmed up it could mean there is an internal coolant leak. This is often accompanied by a sweet smell.
If you see smoke coming from under the hood of your vehicle this indicates a serious problem. Your car is overheating, this could be because of low coolant in the radiator or another problem with the radiator.
No, the engine exhaust is what comes out of the tailpipe.
White smoke from the exhaust is caused by coolant leaking into the combustion chamber. You either have a cracked head or you did not install the gasket properly.
It comes out of the vacuums exhaust equally as smelly