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Testing Idle Air Control Valve Solenoid


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12 replies to this topic

#1 yblocker

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Posted 15 October 2013 - 07:22 PM

Car is a '92 Loyale ea82.  I have three IACV solenoids laying about and each one offers a resistance of about 100 ohms.  When 12v is applied directly to the terminals all is silent.  All three.  Are all three bad?



#2 yblocker

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Posted 16 October 2013 - 06:58 AM

I'll give this a bump and state the question better.  I have been going through the idle control system, and would like to test the solenoid that operates the idle air valve. I have the solenoid (or motor actually) on the bench with a couple of spares. Should these things operate when a 12v source is applied?  I get no signs of life,,,,



#3 ivans imports

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Posted 16 October 2013 - 09:07 AM

Throttle body hard stop must be set right or dosent make idle contact in tps and will not let ecu gointo idle mode



#4 yblocker

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Posted 16 October 2013 - 09:30 AM

Was having slightly high idle speed issues which caused a failed smog test.  I had backed out the throttle stop screw to attempt to drop idle speed. I know that's considered heresy.... Last night I pulled the TB off the manifold, and set the throttle stop so that it's just touching the cam then about 3/4 turn more.  The throttle blade doesn't hang, and that adjustment seems fine.  I then set the throttle position switch to the book so it makes contact when closed but then opens when a .032 inch feeler gauge is inserted between the stop screw and cam, but is still closed with a .028 feeler.

 

I have checked all vacuum lines and have replaced the ones that had hard leaky ends.  I will replace the TB base rubber gasket too.

I pulled the IACV off and soaked it in biodiesel which cleaned it up nicely.  So now I'm to the point of checking the solenoid/motor which is the reason for the above question.



#5 ivans imports

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Posted 16 October 2013 - 09:33 AM

You can hear it in action makes a huming noise in the intake pipe whooooooooooo louder it is the better its working and if working should have high idle cold about 1500-2000 cold



#6 yblocker

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Posted 16 October 2013 - 09:43 AM

Thank you for the reply.  Can I test the solenoid itself off the car?  I have three of these solenoids and find it hard to believe that all three are bad, but I may be that I'm missing something. 12v to the terminals should cause some response right? Is there a spec for resistance between the terminals?



#7 DaveT

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Posted 19 October 2013 - 07:34 PM

There are 2 wires in the plug on the coil of the air valve.  Apply 12V to the 2 wires.  You should hear a click.  The  air path through the 3 air ports should change.   1 is the  "Common" port, the other 2 are the normally open and normally closed.

 

 



#8 yblocker

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Posted 19 October 2013 - 10:06 PM

All three of the ones I have ohm the same.  All three make no noise when 12v is applied.  Guess I have to start looking for one....



#9 86 Wonder Wedge

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Posted 19 October 2013 - 10:17 PM

Try reversing the polarity (swapping the ground and 12V) If you apply the voltage to the wrong the terminals, it will "push" the armature in the wrong direction and won't click. If you're getting a resistance reading (meaning the wiring is not broken) then the solenoid will work.

 

You can also remove the round solenoid body from the valve housing and try to move the plunger by hand.

 

Do you have the FSM test-tree for the IAC valve?



#10 DangerDussault

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Posted 20 October 2013 - 06:51 PM

I'm have the same problem with my IAC in 87 turbo RX any know where I can another? Auto part stores in my areas all have the wrong one

#11 ruparts

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Posted 20 October 2013 - 09:16 PM

hi,

  i think these don't just have a on - off operation,  they receive a signal from the cts through the ecm which makes the actual opening a bit more or a bit less depending on the temp the sensor is seeing.  i am not sure how to fake them to work on the bench , but  , check to see if the actual air opening part that controls the air flow through it is  free to move  some in either direction,, if totally stuck it won't work anyway with  voltage.    they are pretty much closed with the engine hot so cold they would be mostly open i believe.   it was my thinking the valve is spring loaded to be open  when cold, and as engine temp comes up , they get a increase in signal to gradually overcome the spring  until the valve is mostly closed with a  "at operating temp" engine.



#12 yblocker

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Posted 21 October 2013 - 12:47 PM

ruparts-

 

I think you are probably right.  The solenoids I have all ohm about the same, but don't seem to operate with 12v on the bench. Installed on the car however, it's obviously working, since the cold idle is high then drops by itself after a few minutes without touching the throttle.

 

I have several posts on the same car (92 Loyale) on the board lately related to solving a high warm idle.  In the end I think the main culprit was an intermittent coolant temp sensor.  It would cause the idle to fluctuate too, and cause a CEL while the idle wandered back and fort.  The CEL would come on them go off again several times during warm up.  A different sensor procured from a local Pick N Pull seems to have solved it.  The replacement sensor tests consistently whereas the other one tested open sometimes and seemed OK other times.



#13 ivans imports

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Posted 22 October 2013 - 09:38 AM

I have seen the wire harness break close to the main plug on engine harness or the pins do not plug in right check the do a contanuity test from engine harness plug to idle motor look for damaged wire or plug termanal






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