i have a 86 montero, and was curiouse how come my check engine light never comes on, even when i unplugged the o2 sensore. then i realized i dont have one. how do you know when somethign goes bad like the o2 sensore. and also on a carborated motor, how does the o2 sensore adjust the mixture?

95 rodeo 3.2 liter 5 speed 4 wheel drive. 2" lift. poly bushings. 2 1/4 manderal bent exhaust flow master muff. asin manual hubs, relocated ball joints, custom air intake system

92 rodeo 3.1 2wd auto (wifes)