I was helping a friend welding up a project for him. We were using a powermig 140c with .035 fluxcore. This was my first time with fluxcore but my mig welds look good and are sound. The porosity drove me nuts. Started at the recommended settings, cleaned everything with an angle grinder, made sure I had a good ground. I started to think that the porosity was just something you had to live with using fluxcore. Well, as I spent some time thinking about the problem, I remembered someone here talking about adverse effects of using an extension cord on a welder. The extension cord was a must because of location, so I took over my 10 gauge 100 footer. Didn't touch the settings on the machine and presto, like magic, good looking clean (except for flux) welds. Just passing this on. Reading about it here (probably a lot of months ago) led me to the solution to my problem.