I keep hearing that multicannons are not good against shields. With the incendiary efx they are great vs shields.
to be honest you dont need to engineer your stuff...... sure that stuff helps, but I actually think getting a handle on the base gear in the game and then looking at engineers as the icing on the cake is better than just relying on that stuff as a crutch.
IF OP is in an E rated sidey and taking on a FGS then it makes sense things are going sideways.
if however he is in a medium specced vanilla vulture and is getting taken down by cobras then the issue is different. Either way am sure OP is doing something wrong somewhere and can get himself sorted without resorting to engineers.
edit.. mining Asp..... I dunno it seems strange to me. Perhaps the game has gotten massively harder and i have not noticed. out of curiosity i may take my exploration asp out and do some combat and see

.
I spent a lot of time doing combat in an asp but that was some time ago now.