How much does idle control valve affect idle? I put new one and still idles rough.

Question

I was told that my once a week or twice rough idling was my idle control valve going out. I took it out and it was solid black with carbon and I installed a new one. The thing is it is still doing the random rough idle with this new one and new plugs wires, cap, rotor.

Answer 1

depends what car?? its usually the throttle sensor on fords,speed sensor if it stalls when stopping.

Answer 2

the idle control valve completely controls idle speed but speed is not a ROUGH idle, to offer any reasonable advice you need to tell us year make model engine and any other info you can such as when does the problem show up (hot, cold, damp)

Answer 3

Dont know what type of car.  Could need to be adjusted.  Some need to have some electronics disassembled before adjusting.  

Another thing may be a faulty throttle position sensor.  Many are notorious for causing idle surging.

Answer 4

you may have carbon build up else where. for instance on the injectors or on the valves, which would affect your idle quality. have your fuel system cleaned

Good luck