here's the way it works. the wire gets hot. the faster the air moves, the cooler the wire. the ecu sees this and increases voltage to maintain temp. on the wire. the voltage increase then drives injector pulse higher. a resistance check will tell you if the wire is in 1 piece, dirty or not. a voltage check tells you if it's ok at specified points. you're correct to a point, a dirty wire won't measure enough and therefore demand more heat as a clean 1. good luck, chuck.