Fuel Trims

[Geo1]

Help, Polo 1.2 2007, the engine has a small misfire, Checked with Foxwell scanner misfire on no 1 cylinder? looking at the fuel trims data the

shorts trims fluctuating - 3% to 9 %, the long fuel trims stay at 0, Should the engine have both long and short fuel trims? or just one?

No air leaks, new plugs, fuel filter.

Any recommendations greatly appreciated.