Idle Control Valve

[mikej]

Can any of you experts out there tell me exactly how this valve works and what would the symptoms would be when failing or failed??? ;)

[seatkid]

Can any of you experts out there tell me exactly how this valve works and what would the symptoms would be when failing or failed??? ;)

 

This is fitted on the (Ford) petrol engine, it is a small solenoid operated air valve connected to either side of the main throttle plate. When you lift your foot off the accelerator pedal, the main throttle plate closes, shutting off all air to the engine. The ecu then commands the idle control valve to open to allow enough air for the engine to idle. Because the ECU monitors engine speed it can increase or decrese the amount of air supplied via this valve, thereby maintaining a steady idle speed, irrespective of small changes in load e.g. due to alternator, a/c, engine temperature, etc.

 

Problems with the valve is when it gets gummed up with sticky goo from the oil/petrol vapour floating around there. Basically the valve can stick open/closed/halfway. This leads to erratic idle speed control and often the engine will stall after its been on the overrun (slowing down to stop at a junction for instance) because the valve closes on the overun to conserve fuel/giving some engine braking. Alternatively sometimes the idle speed remains very high and takes a while to return to normal (if at all)

 

Or at least I think thats what it does.... ;)

Edited July 8, 2009 by seatkid

[mikej]

QUOTE Or at least I think thats what it does....

 

Well i couldn't have come up with that so that'll do for me !

thanks for the quick reply

mike..