[Skimmer]

Are you using AddVehicleComponent to add mods?

Because OnVehicleMod is not called by AddVehicleComponent.

Check this https://sampwiki.blast.hk/wiki/OnVehicleMod

EDIT: If so you can create your custom function to add mods.

pawn Код:

AddVehicleComponentEx(vehicleid, componentid)
{
    AddVehicleComponent(vehicleid, componentid);
    SaveVehMods(vehicleid, componentid); 
}

Then replace all AddVehicleComponent with AddVehicleComponentEx.