So I took my car to the dealership the other day and after a few hours of upgrading ECM w/ idle air relearn and trying TSBs (to no avail b/c my car won't keep ANY idle) I found out that I have P0505 for a bad IACV, which I'm going to replace in the next couple of weeks, but I wasn't sure on whether or not the ECM would have to be replaced as well. If so, does it have to be replaced or just updated again once the new IACV is in... and why? I also have found some links, etc... on here on how to replace the IACV and ECM, but if anyone has any that they would like to post, that would be great too. As always, thank you to everyone for your help!

 

You may or may not have to replace ECM.

It depending on how bad your IACV is and if it fried the ECM.

Start with IACV, see if you can get the car to relearn and idle/accelerate properly, then take it from there.

 

it probably takes a maximum 30 minutes to remove the ecm and check. it can be done much faster than that depending on how much you struggle with the screws

http://youtu.be/pTfnQlxrE-Y
http://youtu.be/sVE93cOMz9s

its a pretty visible failure and easy to check so why not? my understanding was the ecm failure was linked to the specific failure of the iacv motor flooding with coolant and shorting it so you may be ok.

also theres a way to manually do the idle relearn so you don't need to go to the dealer, check the fsm for your model year. i've also read if you disconnect the battery for a few days the car will do it on it's own.