Normally, a repair shop will spend several thousand for a machine that pumps smoke into your car's engine or EVAP system to find leaks. These leaks produce error codes or rough running engines.

Smoke is introduced into the EVAP system by unplugging one of the hoses and pouring in smoke under light pressure. They you just look for where the smoke comes out. Not good on a windy day!

Here is an example of a DIY smoke machine:

http://www.youtube.com/watch?v=HRiK2HEA3QQ

Others have made simpler designs using a 2 liter bottle with a smoky thing inside and squeezing the bottle. I like the youtube version as well because you could hook up an electric tire pump (just beware, you do not want to over pressure the system, so leave the pump connection loose).

To check for manifold leaks, just plug it into the vacuum tree and see what happens.

Of course, cigar smoke is not for everyone!