A certain amount of am coughing for some folks is normal. You may just be coughing up gunk from smoking. With that said, Coastal Cowboy has raised several valid issues for why you may be coughing with your vape, so if you do post what setup and e-juice you are using, that may help isolate the problem. Is it a different vape than what you started with the first time you switched? You may find that changing one tiny variable may be the reason for coughing more...
Good luck!
Anna