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Discussion Starter #1
My 87 2.0 SI has an idle speed problem. It can be a little difficult to start, but once it does, it idles around 2500. Once heated up, that idle increases to roughly 3000 rpm. The fast idle valve (the valve on the TB closest to the firewall that you access by removing 2 philips head screws) is already cranked all the way clockwise, as suggested by various sources. The throttle cable is not tight, and the throttle position adjustment screw makes no difference.

To check for vacuum leaks, I sprayed starting fluid all over all the vacuum lines while the engine was running, listening for changes in rpm. When I sprayed in the location shown by the green dot in the following photo, I got a significant decrease in rpm:

Image: https://ibb.co/jBf7SG


When I spray on top of the intake manifold gasket, I get no change. It only happens when I spray underneath. Are there any vacuum lines or other things down there that this could be, or is it the intake manifold gasket?

Could a leaking gasket be the cause of such a fast idle, or do I have more issues?

BTW, the car runs fine other than the fast idle.
 

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I forgot to add that idle air control valve (the one I turned clockwise) has 2 vacuum ports on the bottom. The bottom-most one is not connected to anything. I don't know what it's for, but I tried both plugging it and connecting it to a vacuum source and the idle did not change. What should it be connected to?
 
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