Rep Power: 0

okay so it started with i bought this 98 civic si , automatic , bone stock, the car sat for 2 years, did all the work it needed, But i cannot figure out the idle problem.

SO the car idles at like 1300 to 1400 when the engine light is off, as soon as it comes on the car idles up to 1500- 1900. engine code po505, idle air control.

i have cleaned the IAC i and put it back on with no fix. so i bought a brand new one thinking the old one was just wore out. But that did not work either.

The plug that connects to the IAC motor does have power.

IF i take off the air box, and air intake tube. and i cover the oval shaped hole inside the throttle body, its above the IAC the car idles PERFECT ! i can feel the IAC pulling on my finger with how much air its sucking.

Something is telling the IAC to go wide open. But i dont know what could be causing it ?

MAP sensor ? bad ECU ?? or TPS ??

My ECU is a P2P-C84 (UT)

any info would be great thanks