95 wrx motor hum

[darren23]

hi there im having trouble with my 95 wrx motor making a humming noise. it goes away when i unplug the idle control sensor. i have replaced the whole unit with a new one and still the hum persists with ics plugged in and screwed into place. any ideas on what could be causing this.

[Rosssub]

Is your ICV buzzing, an electrical fast ticking? Does the car still idle ok?

Could maybe be caused by low voltage/amps getting to the valve (bad connection), or volt loss through a bad earth. Pretty much it\'s not getting enough power so it\'s having a seizure, have you got a multi meter?

[darren23]

the car idles ok icv is buzzing

[Rosssub]

 Rosssub said:

Could maybe be caused by low voltage/amps getting to the valve (bad connection), or volt loss through a bad earth. Pretty much it\'s not getting enough power so it\'s having a seizure, have you got a multi meter?

See what voltage the ICV is getting at idle.

Edit: IACV-Idle air control valve solenoid

[darren23]

hi there i checked the voltage at idle. its sitting around the 14 volt mark. is that right?

[Rosssub]

Yeah I think full volts at idle is right, to hold it open. I\'m pretty sure the Idle control valve can be taken apart and cleaned out, might be all it needs.

Edit: This one:

http://forums.nasioc.com/forums/showthread.php?t=781242

[darren23]

thanks ill give it a go tomorrow

[Timmah]

Are you able to upload a video to YouTube for us?

[darren23]

hi i dont have a video camera.

[log1call]

The Idle control valve uses modulated pulse width to keep it open the right amount. Modulated pulse means it\'s turned on and off with different ratios of on and off. If the butterfly settings, engine condition and hoses etc are correct. the valve is powered on approximately 45 percent of the time, and 55 percent of the time it\'s off. This switching is happening hundreds of times per minute.

The buzz is probably because of the switching.. but they don\'t normally make a noise. I\'d guess that both valves you have tried has some play in it that is making the noise.