What exactly dose the variable resistor do that plugs into the emissions harness and is bolted to the passenger fender. Dose it control air fule or what. Because if it dose than could anyone help me on how to set is?

 

its only for setting it how rich or lean you want the car to run at idle. i set it to lean all the way. it didnty do jack suak,. so i unpluged it
it idles better now

 

Its the air fuel mixture swtich which is set at the factory and glued in place. If it spins freely its broke.