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  #1  
Old 11-18-2003, 01:51 PM
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higher idle after cleaning idle control valve

Hello all,

My idle raises almost 150rpm after I cleaned the ICV. With gear it's about 750rpm while in neutral or park it's around 900rpm. What have I done here ?

The ICV had been pretty dirty before I cleaned it. Not a problem before but I disliked the rpm surges (50+rpm) in park.

If this is a result of a cleaned valve, would it adjust itself or do I need to bring it to a shop to have it re-calibrated ?

Thanks in advance for any inputs!
Frank.
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Old 11-18-2003, 02:54 PM
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Disconnect the plug to the ICV. If the engine still idles high, you have a vacuum leak or the valve is not returning properly. In our 190E, this happened when I got it installed backwards (airpath).

Steve
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  #3  
Old 11-18-2003, 03:08 PM
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Steve,

I think you're on something here...One connector pin was marked red (for hot wire ?)...I could check with a voltmeter but on top of your head, is the hot wire black or black with yellow stripe ?

Thanks,
Frank.
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  #4  
Old 11-18-2003, 03:13 PM
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In order for the engine to idle properly it needs the correct signal that the throttle is in the idle position.

Check the throttle position switch and the linkage microswitch to be sure they are operating properly.

My suspicion is that many idle problems are caused by sticky switches, but checking them is rarely mentioned in the threads on idle speed problems.

Duke
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Old 11-18-2003, 11:08 PM
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hi duke,

where exactly are these switches? TIA
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  #6  
Old 11-19-2003, 12:39 AM
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The generic locations should be the same as on my six. The "throttle postion switch" is on the end of the throttle valve shaft, which is under the fuel distributor on my six. It is an enclosed switch with a built in pigtail with a connector on the top of the manifold, which can be disconnected, and the switch can be tested for function.

I can't recall if the switch is closed of open at the idle position, but if you connect and ohm meter the resistance should go from zero to infinity, or vice versa when the throttle is excercised from idle to open. If you don't get a consistent jump in the meter as you manually excercise the throttle linkage, it is sticky. I was able to douse mine with mineral spirits, then WD-40, and it started working consistently and my high idle went away.

There is also a "microswitch" on the linkage, and it should also be tested for proper function in a similar manner.

Duke
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Old 11-19-2003, 11:11 AM
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Quote:
Originally posted by sjcruiser
Steve,

I think you're on something here...One connector pin was marked red (for hot wire ?)...I could check with a voltmeter but on top of your head, is the hot wire black or black with yellow stripe ?

Thanks,
Frank.
The 'backwards' I was referring to is the airflow direction. It may not be possible to do this with all ICV's, but it was on our 190E. Proper direction is air flows in from the airflow meter (bottom) and out into the intake manifold (top). An arrow on the valve body indicates direction.

Steve
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