MIG weld ground question

[Argeo]

What would cause the ground to spark when I am trying to weld? The other night I put a little ding in my rocker cover somehow by the ground. It was like the welding was happening at the ground.

Does popping indicate not enough heat or moving to fast or both. Suddenly, the welder has been popping and not welding great. Ground problem or the area I am welding not clean enough?

I am know welding underneight the rocker cover where the sill curves upward. No longer doing panals, should that effect my weld? Still welding 16 guage steel.

Thanks,

David