hagford

Hello, I am a first time civic owner and a new member, normally I am able to find my answers searching through posts but this one seems a little harder to track down. so here is the story

ABOUT THE CAR:
2000 civic CX
1.6 single cam manual, i think d16y7 with the black air box on top
Throws a p505 IAC code

WHAT HAS BEEN REPLACED:
-Looks like someone before me threw a junk yard throttle body on judging by the yellow paint on it
-I replaced the IAC valve

THE STORY: so the car has interesting symptoms, i first noticed a lurching or bucking on deceleration at lower R's, you would let off the gas and you could feel the engine slow you down much harder. also if i push in the clutch and get it around 2000 rpm the engine wont hold a steady level, she bounces kind of like hitting the rev limiter.ALSO IF YOU TURN THE CAR OFF AND START IT BACK UP IT RUNS PERFECT.(ALSO IT IDLES FINE). so I brought it in and it had a P505 code so i took a look at the IAC which someone had siliconed to the throttle body, figured I should just buy a new one ($180 bucks).

I put the new one in and drove the car down the road and it was blowing a ton of smoke, I blame the Auto Zone junk rubber band gasket, so I said screw it and bypassed the coolant lines in the iac and I re seated the gasket to get a "better" seal. a day later it throws the same code and does the same thing, a strange thing is if I unplug the IAC sensor it re creates the problem so that means it is in the full closed position also if I plug the IAC sensor back in it does not go back to normal, the problem will continue until the key is off then back on, so im thinking maybe a computer problem... I just don know.

hagford

also maybe a vacuum leak that only happens in the closed position...