playing with W201 fuel mixture

[ssanmor]

Hello all.
I have tried to enrich the mixture of my 190E 2.3, 1992, turning the 3mm hex screw 1.5turns clockwise. The car runs a bit more, but has a strong gasoine smell, and also the idle is very unstable. This was only a test and this afternoon I am going to return it to its original position. Can a relatively short trip (I have run about 100Km) damage the cat or something?
And...how is it possible that I have noticed any difference when the KE system is supposed to compensate the mixture so it remains always the same?
I know that before, it was just right, is 1.5 turns too much and has exceeded the KE capabilities to maintain closed loop?

Thanks!