Bubbles in the weld? Gasless MIG

Hi all, have purchased a new CIG gasless mig welder which is coping a beating at the moment. Have notieced with a few welds that it beads up more and bubbles then pops leaving a crater effect. May be answering myself, but could this be happening if surface dirty and not penetrating and then balling up?

Hope this makes sense to someone!

sounds like porosity,like when you use a gas mig without gas,you havent changed wire lately?? but just make sure surface is clean,or is the leads connected the right way round ,as my gas gasless you have to swap for different wire types