Join Date: Aug 2012
Location: Austin, Texas
Car: 2001 VDC/SC One of a Kind
Feedback Score: 2 reviews
The throttle position sensor may be holding the throttle plate open. The throttle is open already, so disconnecting the IACV allows for the engine to operate because it is able to pull air in past the throttle plate. Or you have something disconnected and its creating a vacuum leak.
Just because I thought of it, and it may come up somewhere, it may be good for readers to know that an IACV valve opens under throttle, more so than at idle. The computer does this so it can control the idle down. When you let off the throttle, the ECM reduces the IACV slowly to normal idle. In this way, the idle doesn't drop too fast and flood the engine or cause a stumble. All management actuators react better to control the engine operation, i.e. air, fuel, fire.