idle control valve

[bones]

ive got a idle control valve issue.1989 M20.supposed to increase idle on start and maintain 750 rpm reguardless of engine demands,ie ac,alternator,and low temp.mine is struggleing at best.the book says when you remove the electrical connector the idle should increase to approx 2000 rpm.mine dosent,ive got power to the valve and it hums slightly.how is the rotary valve supposed to open simply by removing the connector?does vacume pull rotate the valve open?. thanks bones

[bones]

just throwing this back to the front

[timandbim]

i thought it was humming but really it wasn't. it only gave me trouble when i was starting but a cold start was a real effort every time and i hate to think how much gas i sent through the exhaust system playing with the gas pedal... afterwards it would run great though, even before warming up. my revs didn't increase either when i pulled the plug, but it still passed a voltage test. i bought a used one for $25 on ebay and now it really does hum and i have no starting issues at all... i highly recommend switching it... the price is right and it takes about 3 seconds to do. i was thinking of pulling my old one apart... i will take a photo for you if i do. i think it will probably be just a mechanism for turning the valve attached to a resistor or even a little motor or something... (?) also, the replacement part that i got was pretty filthy inside... enough for it to stick if you didn't clean it... but you probably checked that already...


ive got a idle control valve issue.1989 M20.supposed to increase idle on start and maintain 750 rpm reguardless of engine demands,ie ac,alternator,and low temp.mine is struggleing at best.the book says when you remove the electrical connector the idle should increase to approx 2000 rpm.mine dosent,ive got power to the valve and it hums slightly.how is the rotary valve supposed to open simply by removing the connector?does vacume pull rotate the valve open?. thanks bones

[E34-520iSE]

Hi Bones,
It sounds like your ICV is stuck closed. As Timandbim says, a used replacement costs peanuts. I also bought a couple from ebay, to keep for spares. It should idle high when cold (approx 1200rpm) then 750rpm when cold, consistantly, without surging.

HTH,

Shaun M