My car loan is completly in my exs name. But the car itself is 100% in my name. If he doesn't pay his payments can they take a car that's in my name?

Sure can - if he has a car loan with the car as collateral, then failure to pay allows the lien holder to take the car.

Yes, they sure can. You don't get a free car because he didn't pay. Its NOT your car until it is paid off.

If the ignition timing is way off, your car might backfire and go pow!

If the lender has a lien on the title, it can be repo'd.