Ever since I bought the S in may 2008 I have experienced the idle getting very low and rough after a stop and go drive like when driving from one red light just have to stop at another one in a short distance. I have done the map whack zip tied the map sensor relearn procedure etc. It seemed to have gone away when I installed the K&N intake, but persisted about a week after. About a day ago I cleaned the IACV even though it wasn't dirty at all. After reinstallation I was fiddling around with the plug with the car at idle and if I pulled it aft the very little bit the intake would quit making the humming noise aftermarket intakes always make. Also the same thing would happen if I pushed it towards the passenger side. So my question is what should I do jury rig some tip ties like the map and make it hum or not? No IACV cell is being thrown unless I unplug it. Honda should have made their plugs more sturdy on the S.

 

I would replace the IAC.

 

I assume you've already changed the PCV, cleaned the throttle body and adjusted the throttle linkage. I can tell you that my S2000 does not like this triple digit temp run we're on here in Texas. So don't judge anything about the performance of your car while the temps are this high.

 

so you think the jack on the IAC is messed up. I zip tied it and seems to be holding up pretty well. After a drive to do some errands. Wish I had a known good one to substitute. To see if it is a good fix or not cause it could be the IAC or the locking mechanism in the Plug.

 

Yes I have done all of those too. It has been pretty hot here in Georgia and humid. I try to do my troubleshooting with these problems at night. When it is slightly cooler.

 

Sounds like it...that's what generally goes bad on our MAP...that is why the zip tie works. If the zip tie is working for you on the IAC, no reason not to keep it for a while to see if it will cure the problem permanently for you.

 

Our IACVs operate by pulses, with a frequency of 488Hz. That's 488 times a second. That could be causing the humming, and when you pull/push it, it simply transfers/isolates the humming.

Wanna know how I know? Load the free AEMPro software for AEM EMS, it'll come with the necessary initial calibrations for our car. load it up on your computer, open Idle>Advanced Idle>options (or something) and it'll be there. You can change that frequency, I did, but with the car running. It makes the car idle way weird!

 

Run a test on the IAC. You can do 2 tests on of the tests you can do is remove the air intake tube start the car and place your finger over the port inside the Throttle body if the car shuts off the IAC is bad. Another test is just simply unplug the IAC while the car is running if the car DOESNT react its Bad.

 

it's also very easy to make sure it's getting the voltage it's supposed to. I just replaced the IAC valve on my car- mostly, my car had a very lumpy idle in the 1600-1700rpm range when fully warm, or it would just barely hold 500rpm. Closing the two ports in the throttle body is probably the easiest way to verify what's causing the issue, and if you don't have a multimeter around, I'd pick one up just to make sure it's not an electrical issue before buying a replacement IAC valve.