odd idle control valve situation

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blockerb
Posts: 127
Joined: Apr 28, 2011 9:58 AM

odd idle control valve situation

Post by blockerb »

I can't figure out if my idle control valve is bad or not.

started car after sitting for a few weeks and battery died. replaced battery and started rough and would not hold idle until warmed up and even then was quite rough but RPM remain fairly constant after warmed up. disconnect ICV connector and rms fluctuate between 500-600 to 1200-1500 as expected and reconnecting brings idle back to the original level.

I turn on the ignition w/o starting the engine and get not vibration from ICV although disconnecting and reconnecting the connector seems to quickly open/close the valve. Also putting 12v on the ICV terminals closes and opens the valve quickly and tightly

restistance between the two ICV terminals is right under 10ohms. So everthing except the fact that the ICV doesn't vibrate in the "ignition on" position points to the fact that the ICV is working.

This led me to wonder if the ICM was bad.

checked voltage across the ICM connector terminals in the "ignition on" position and and measures at ~11.5 v resistance at the ICM between. measured the resistance across the 1 and 5 pins on the 28 pin ICM connector and and got ~10 ohms.

Checked for battery voltage between the 2 and 4 pins in the "ignition on" position and got just under 12v.

so it seems like the ICV "might" be good and the ICM is "likely" good but nothing conclusive. Is it possible for the ICM to be good and not have any vibration in the "ignition on" position? I'm leaning towards a vacuum leak somewhere. any other conclusive tests i can do?
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: odd idle control valve situation

Post by Mike W. »

Others will hopefully chime in, but I'm not sure the vibrating test doesn't just apply to 535's and Super E's, which share the same valve. They are 3 wire and the 533/regular 528e are two wire.
MattC
Posts: 220
Joined: Jun 03, 2016 1:16 PM
Location: Bucks County, PA

Re: odd idle control valve situation

Post by MattC »

I have an '84 533 with the 2-terminal ICV and will say that, ignition ON, the humming/vibrating can be very faint sometimes. Try holding a screwdriver tip to the valve body and your ear to the handle. My only other advice is to unplug the connector from the valve and check that you have voltage there with the ignition on.
blockerb
Posts: 127
Joined: Apr 28, 2011 9:58 AM

Re: odd idle control valve situation -SOLVED

Post by blockerb »

turns out it wasn't the ICV or the ICM or the TPS. There was a hole in the intake boot, which was original to the car. So replaced that with a new one and it idles fine now. Still can't really hear a vibration but all the voltage/resitance tests were successful Also ran through the various tests on Rod'd technical pages and confirmed that the iCM and ICV were working correctly.

https://www.mye28.com/tech/rods_pages/
Sharrah
Posts: 4
Joined: May 16, 2021 5:15 AM
Location: Bahrain

Re: odd idle control valve situation

Post by Sharrah »

Good to know that you solved this issue and thank you for sharing the testing results and the solution.
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