Idle goes up and down on 1996 Honda Civic

Just replaced my radiator and my car wont idle. It goes up and down between 1000 and 2000 rpms. I tried to bleed the air out of the cooling system per recommendations from friends and some forums and engine continues to rev up and down. I checked for leaks in vacuum hoses and found nothing. What else could it be? Engine ran fine before I replaced the radiator for the 3 years that I have had the car.

by in White Plains, NY on October 03, 2011
2 answers 1 comment
ANSWER by on October 03, 2011
The engine idle speed will race up and down on a Honda if the coolant level is low or air is trapped in the cooling system, I suspect that is all that is wrong if the idle speed was OK prior to the radiator was replaced.
COMMENT by on October 07, 2011
Do you have any tips on how to get the air trapped in my cooling system out? I have put the heat all the way to the hottest setting with the fan off and with the radiator capped removed. I noticed some air bubbles coming out of the radiator and let it run for about twenty minutes. Afterwards, the idle was still racing up and down. Should I keep letting the car run until all the air bubbles stop coming out of the radiator and not worry about the time? (I also changed the O2 Sensor. Just as a sidenote)
ANSWER by on January 15, 2012
Check to see that your ECT sensor is connected its the bigger sensor on the thermostat housing. then check your iac( proceedures for all this can be accesed by buying a Haynes repair manual for your honda).
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