Hey y'all. My truck smokes when I floor it going down the interstate. When I floor it a little puff of black smoke shoots off. What's going on with that? Thanks!

And if any of you could help with this, I'm working on my cousin's '97? Jetta and it wont turn over at all. We jumped it and while being jumped, the motor will crank up for about 1.5 seconds and then shut off. When we disconnect the jumper cables and try to crank it up it wont do anything..dead battery. Could the battery be the reason why the motor wont stay cranked? The car has also been sitting there for a year, but he swears he turned it on last week and ran it for about 20 seconds. Thanks again!