I bypassed the coolant hoses that go to the throttle body and now the car idles high. At first I thought it was a vacuum leak but today I pulled the plug from the idle control valve and the idle dropped to normal levels.

Did it just decide to break at the same time I did the modification or does the coolant flow close enough to the control valve to make a difference in behavior?

 

The hot water that runs through the hoses you eliminated heated an item called the thermal wax module, that module pushes down on a cam that when warm releases the high idle. Most people wire it down out of the way (getto) other remove it all together.

 

If you have the OEM throttle body setup, there is a wax-controlled rod that changes the position of the throttle stop when the car is cold. According to my EMS, the throttle will be held open to about 5%. This will cause the car to idle high when cold.

As coolant warms the wax it will melt, gradually allowing the throttle to fully close which will cause the idle to drop. My datalogs show about 5% open at 60F, about 4% at 120F, and about 1% at 180F.

Unless you've disabled the fast idle cam on the throttle, this is probably what is happening. Rob Robinette wrote a nice how-to with photos showing how to do it:
http://robrobinette.com/throttle_body_coolant.htm


-s-

 

there is a spring loaded bracked that you must bend out of the way or completely remove....i'll see if i can find a pic. otherwise, it locks in and causes the idle to be higher

---edit---

here it is...i've circled it in red. this hammer piece needs to be removed or bent away from the throttle body.

 

Cool, that fixed it. While at work I just threw a metal cap on the screw to space it out far enough. I had no idea the cold idle was controlled mechanically.

You guys are the best.