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91 civic idles high & low in neutral

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  #11  
Old 07-04-2009, 05:25 AM
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which thermosensor should I disconect? the pic shows 2. I will look for the engine #. Is their a way that someone could make a car idle like this if they were modifieing it for raceing?
 
  #12  
Old 07-04-2009, 07:05 AM
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D15B1 is on the engine
 

Last edited by warnergen; 07-04-2009 at 07:46 AM.
  #13  
Old 07-04-2009, 07:58 AM
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You have the 1.5 liter engine (D15B1).

The relevant thermosensor is now circled in red.

Do you have or can you borrow or purchase a digital multimeter (cost = about $20) to measure the resistance across the two terminals of the unplugged IACV? Does the hunting idle cease if you unplug the IACV (EACV) connector?

See diagram below for instructions on bleeding the cooling system. You can skip steps 2-5. Afterward, adjust the idle speed with the idle screw (see diagram in previous post).

Do you have a reason to believe that the stock engine has been modified?

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Last edited by RonJ; 07-04-2009 at 08:02 AM.
  #14  
Old 07-04-2009, 08:17 AM
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I cant get a digital multimeter right now. should I have the the car running when I unplug the IACU connector? If yes then should I unplug it while the engine is doing the hunting idle? why is it called hunting idle? also, if I cant get it fixed, is it safe to drive like this? will it cause other problems?
 

Last edited by warnergen; 07-04-2009 at 08:20 AM.
  #15  
Old 07-04-2009, 08:33 AM
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Originally Posted by warnergen
I cant get a digital multimeter right now.
Maybe someone you know has a multimeter and would let you borrow it? The resistance test is one way to test whether the IACV is bad.

should I have the the car running when I unplug the IACU connector? If yes then should I unplug it while the engine is doing the hunting idle?
Yes to both questions.

why is it called hunting idle?
A hunting idle is just another way to say that the idle speed is constantly fluctuating as if trying but not succeeding in achieving a steady idle speed.

also, if I cant get it fixed, is it safe to drive like this? will it cause other problems?
You are unlikely to cause any engine damage by driving a car with a hunting idle, though it will probably reduce your gas mileage. Safety, however, is a potential issue if you feel that the engine may stall at an inopportune moment or that the car may lurch in an uncontrolled manner.

You mentioned that the hunting idle occurs with the clutch pedal depressed and the transmission in neutral. What about with the clutch pedal not depressed and the transmission in neutral?
 
  #16  
Old 07-04-2009, 08:37 AM
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yes, even with it sitting in neutral without the clutch in it still does it.
 
  #17  
Old 07-04-2009, 08:40 AM
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Okay, that's as expected.

By the way, my answer below is also true for the thermosensor.

should I have the the car running when I unplug the IACU connector? If yes then should I unplug it while the engine is doing the hunting idle?
Yes to both questions.
 
  #18  
Old 07-04-2009, 08:50 AM
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ok I let it run untill it started the hunting idle. I unplugged the EACV and their was no difference.
 
  #19  
Old 07-04-2009, 09:12 AM
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Originally Posted by warnergen
ok I let it run untill it started the hunting idle. I unplugged the EACV and their was no difference.
Okay. Now do the same test for the thermosensor, and also the throttle angle sensor located at the base of the throttle body:

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  #20  
Old 07-04-2009, 10:11 AM
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ok I unplugged the Throttle Angle Sensor and the hunting idle stopped & stayed stopped after I plugged it back in. I shut the car off & restarted it & it started the hunting idle untill I unplugged the Throttle Angle Sensor. So do I need to replace that sensor? now after unplugging that my car is flashing 7 times on the code thing.
 


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