Hello I need help with a circuit. Basically I need a 12v water pump to be controlled by a car maf (mass air flow) sensor. As the air flow through the maf sensor increases or decreases the maf sensors output varies from 0v to 5v. I need to control a 12v pump in a PWM fashion with the output of the sensor. So as the sensors output varies the pump pumps more or less water according to the maf sensor. I also need to be able to control the voltage at which the water pump turn on. I want to use this circuit for injecting water into the air intake of a car at a controlled state.