BMWpower,
Looks like the guys provided you with a lot of usefull information. The only thing I can add that appears to be overlooked but may not be a factor, make sure that if the welder was set up for gas prior to yourself using flux cored wire, that you reversed the polarity on the machine. DCEN (DC Electrode Negative) for flux cored, DCEP (DC Electrode Positive) for solid wire with shielding gas. Without reversing the polarity the end welding results will appear similar to what you have described. Another possibility might be the flux cored wire itself. Sometimes the stuff has sat around outside in a damp garage or store shelf, and picked up moisture. This will also cause porosity. If you have not yet determined the problem you might want to try a new roll of wire from a different source. Also, I have a few smaller wire feeds along with my larger industrial sized units. I have tried a flux cored brand named US Forge in all these machines and ended up with less than acceptable results. So if you are using that brand you may want to try something better........good luck