First of all, THANK YOU, for your answers !!
And YES. You have right!
I tried again, with more power, and just a bit lower wire speed.
Very-very Better !
(I weld for first time on the car. For that reason, I tried not to damage the sheet metal with holes.
I observed, that big problem, is 'Earthing'. Best connect with body, means best welding.
It depends from the earthing cable and the contact with body. And whole circuit, machine contact-cable-contact on body.
And if the body is under corosion, the resistance is too high, that means, topically you want more curent!
I think very important, perhaps the most important thing-problem, in this type of welding).
@and Metalart: the kind of gas is: 82% Argon and 18% CO2. and wire 0.6mm, (0.0236in).