I'm TIG welding 4130 on a new roll cage. Every once and a while the weld pool will bubble and fizz and spew like a sparkler. Metal is ground clean and wiped with brake clean so I'm thinking its a gas coverage issue. I'm using a gas lense with 7/16" cup, 3/32" red tungsten, 13 cfm gas flow. Tried cranking the gas up to 16-17 cfm and didn't help. Can someone help me?

Thanks,
Craig