I have a 2004 Ranger Edge with 3.0 V6. I had a cold starting problem and through these forums found out about cleaning the IAC Valve. I did that and it cured the problem. After cleaning it I tested it by turning the ignition on and off, I noticed that the valve was very slow to open and close. This is a solenoid and shouldn't it snap back and forth quickly? Cleaning helped but shouldn't I replace it? Also if it is sticking part way open or closed after the engine is warmed up would it effect gas mileage? Thanks for any help

 

No, it doesn't "snap" open or closed, the computer uses PWM(pulse width modulation) on the Ground wire for the IAC Valve, so voltage doesn't change all that fast, if it did idle would jump around

Sure IF cleaning helped but it still doesn't seem to do steady idles or has hanging idle, then replacing IAC Valve would be next step
You can only use a Motorcraft(Ford) or Hitachi IAC Valves, accept no substitutes, lol, they won't work well

No, on the MPG, unless engine was idling high after warm up, the computer does "on the fly" fuel calculations, so if IAC was open too far or not enough while driving it wouldn't matter because its just using air that already passed through the MAF sensor, so wouldn't effect the calculations, because its not "outside air" like a vacuum leak would be

Now hanging idle is a tough call because of emissions, the computer HOLDS idle high until speedometer drops below 5MPH, that's not a hanging idle that's emissions law, lol

 

Thanks RonD you have answered my questions. If this situation comes back I will replace it. Thanks again