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Old 12-01-2016, 01:45 PM   #1
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Idle control valve-M42

so recently I've been having problems with my e30, I'll drive it and it'll randomly shut off while driving, but start right back up. Usually happens when it's not in gear and it's just sitting idling like going down a hill in neutral. I'm currently cleaning my ICV and from what I understand I'm supposed to hear it rattle and no matter how much I clean it, it's not rattling too much. Seems stuck. Any help would be great...

Also would a faulty alternator cause my car to idle rough/die? I mean I just recently replaced it.. seems to be ok because I did some tests on it..
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Old 12-01-2016, 03:02 PM   #2
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idk about rattling but when it's plugged in and the car power is turned on it should buzz. at least that was my understanding when trying to figure out if mine was bad or not
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Old 12-02-2016, 03:33 PM   #3
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Check alt belt to see if it's tight. Also check ground cable. Idle valve should rattle only when it is off the car., in your hand and you shake it. However it still could be sticking while in operation.
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Old 12-03-2016, 08:03 AM   #4
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That could be a bad relay, my 635CSi did that. Try new Motronic and fuel pump relays.
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Old 02-04-2017, 01:05 PM   #5
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How open does the door on the valve open? Mine will fully close but
Barely open (maybe about an 1/8inch). And is in an open position when not plugged in.
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Old 02-05-2017, 09:11 PM   #6
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Not sure if it's a linear actuator with a camming action or a gear output motor, but it really doesn't matter as they pretty much work or not as long as they are reasonably free of gunk.
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Old 02-05-2017, 10:31 PM   #7
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Gotcha. I
Think I may buy a new one. It doesn't hum, and the door definitely doesn't open all
The way. Pretty
Gummed up even after a can of carb cleaner was use. Hopefully that, new gaskets
Vac lines will
Solve my bucking/hesitation issue.

Thanks for your response
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Old 02-05-2017, 10:47 PM   #8
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Is it a 3 wire bosch one? If so you can make it open and close putting wires to the battery.
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