With my idle adjustment screw all the way in (gsr integra), my idle can only get to a minimum of 750-800 rpm. I'm thinking this probably suggests a vacuum leak, but I'm curious of what effect turning the idle screw all the way in has for other cars. Should the idle get low enough to kill the engine?

 

Are you trying this with the Iacv plugged in? If you're referring to the idle screw that the throttle rotor rests against that controls throttle plate position then with the iac plugged in it will have no effect as that is the cruising idle adjustment and at idle the ecu will use the map reading and tps reading to create an idle between 750 and 850 from what I understand. Did you make any changes to the throttle body leading up to this? Depending on the severity of the possible vacuum leak I would think the idle would be more in the 1000+ rpm range

 

Yeah, I'm talking about the flat head screw on the throttle body. I adjusted it with the idle control valve unplugged and the service connector jumped. If I have a vacuum leak, it must be very small because I can't find it.
Anyway, I need to get my idle lower so I can be sure my base ignition timing is correct.

 

I suppose it's time to start spraying vacuum lines and mounting points with carb cleaner and see if you find something, small leaks are a pain. I recently upgraded my tb and port matched the im and made the mistake of thinking it'd be a quick project...4 hours and a custom throttle cable bracket later I still had a vacuum leak that kept my car idling at 1500 and had to drive it to work, that was an interesting drive lol