ok so ever since i bought the car every so often my car would throw up a code about a malfuction of my IAC, and i would reset the computer and it would be fine for a while and come back . well i found a decently used one cuz i cant afford a new one for now and i put it on today and it started to idle like crazy around 1500 RPM's sotook it out and replaced it with my original one and now she just idles at 1500, drops down slowly to 1100 and back up to 1500 RPMs. am i doing something wrong or are both of my parts faulty now?

 

Try resetting the ECU. If that doenst work, then maybe they are both messed up

 

yea i tried to reset the ECU when i put the old one back in......you gotta disconnect the battery and step on the brake for a few seconds right to reset it right?

 

With the key in the ignition/turned to the on position

 

oh ok, well i just swaped them around and they run about the same, the original one i had just idles high with a slight surge, so i guess im going to have to buy a new one and they're both f**ked now

 

what was the exact code # that your were getting?

 

P0505- Idle Control System Malfunction

 

This can have many differant causes i am currently delaing with this myself. It can be anything from a simple boost/vac leak, ISC, EGR, FIAV, BISS, or MAF. you will need to runa few test before replaceing parts. I would check for Vac leak. here is a idel sure writeup that is very good.
-> Surge
-> http://www.vfaq.com/mods/wayback/BradBauer/engine/surge.html

 

ISC - No it wouldnt cause the revs to jump at all.. it would just idle like *****

EGR - Would throw the EGR code

FIAV - First idle air valve??? Not familiar, cant say

BISS - Again, wouldnt cause the revs to jump.. just idle like *****

MAF - Possible actually... but why would it throw the IAC code?

 

well its weird cuz my car idled fine before i messed with the IAC'sand now even with the original part back on there its idleing at 1200-1500