ok so ill start from what happened to where im at now..
CAR- 2000 civic ex manual with cali emissions.
engine is D16y8 head mated to d15b bottom end.
all obd2 original harness.
So car had no prior issues then this occured... was driving for several hours in and out of stores, typical sunday. Left car running to get a monster drink, come back out to see car idling at 2200 rpm. CEL had come on for P0505 at this time. so i cleared code and cleaned iac valve. even replaced iac and no change.

So i start checking things such as vacuum, all hoses are flexable and in excellent condition i sprayed TB cleaner all over them while engine was hot and no idle change at all.
i did notice coolant resivoir was empty so i added to it and filled the radiator up with about mayby 5-8oz of coolant. was barely low.
i also plugged the port in the TB and noticed my idle did die down from 1800 to about 1000.
i noticed my temp gauge was slow (i had heat but gauge wasnt moving) so i replaced the ETC sensor and now i idle at 1400 cold and hot.
If i pump the brakes fast itll cause the car to do the wah wah dance surge going from 1300-2000 rpm.
radiator cap is good and so is radiator.

any ideas? im putting a brand new IAC on tonight and try to bleed the coolant but im pretty stumped so any advise is good thanks in advance!

 

If you cleaned the IACV and that didn't help, and plugging the IACV hole in the TB helps, then that pretty clearly points to a failed IACV. Replace it, then get back to us.

 

well found out radiator had a small leak in top seam that the stock foam insulator was absorbing. so i replaced that and burped the system for about 2 hours untill it no longer burped for about 30 minutes. i got a iac off a friend that was known to be good (took off his gsr when switching to a aftermarket mani) and idle is still high. then again this part was sitting in his tool box for a couple months so could have went bad mayby? im installing a new out of box iac tonight hoping it fixes this idle. also im going to remove the tb and clean all ports and throw a new gasket on there. any one have any tests or ideas to check before i start tearing into this thing tonight?

 

Does moving the idle screw in and out do anything?

 

ok well after installing a new iac i still had idle surge and high idle. so i said F it and decided to take the car out for a spin, after being on the highway for 20 minutes i went to turn on my cruise control and noticed it didnt work, well I have to say i feel like a giant idiot because to my surprise there was my cruise control vacuum hose dangling in the wind. Connected it and bam car runs beautiful but much better do to cleaning all the ports and etc.

thanks all!