Before Vaping with a New Atty it needs to be completely saturated with E-Liquid. If not it will get burnt taste. It's impossible to get that burnt taste out. You need to try another Atty and make sure that it's good.
Check to see if you received an Authentic TFV4, your box should have a rub off sticker on the front and you can go to Smok Website to verify the Authenticity. By inserting the numbers under the sticker.