With the ignition set to ON but car not running, with jumper in diagnostic test port to test for codes, the fan came on and I could hear a slight sporadic ticking noise from somewhere around the intake plenum. So I broke out my stethoscope and poked around. I could clearly hear the ticking as I touched the plenum, with it getting louder as I got closer to the throttlebody. So I then poked the IAC valve and the ticking got very loud and I could hear a buzzing sound. Could this indicate a bad IAC? Or is that normal? Again, the car was not running, but the ignition was ON and the fan was running and the test port was jumped.

BTW, is it normal for the fan to come on while you jump the test port?

 

That is all normal when the key is on and the engine is not running and the diagnostic port is shorted out. It retracts the IAC pintle.

If you had to take out the IAC for cleaning you would do that for 30 sec to ensure it is retracted all the way and then you could remove it for cleaning,

 

Okay, cleaned the IAC per the instructions on thirdgen.org and man, let me tell you it helped a lot, but the car is still not perfect.

If you recall in my other posts, I was complaining that the car doesn't want to start for a little bit after it's been running. Now, after I have cleaned the IAC, the car will start if I wait only about 30 seconds now after I shut it down, even if it was running for awhile and got really hot. So can the IAC cause the car not to start?? I mean, I could understand if the car would start and wouldn't hold idle, but for it not to start because of the IAC, it just doesn't make sense. But again, it has not completely solved the problem because the car still won't start after it was just shut down. I must still wait about 30 seconds to a minute, but it was better than before where I had to wait 5 minutes in some instances.. I think we're getting closer!

 

I am assuming that you did set the idle? Another way to do it is with an scantool. You set the IAC counts to somwehere between 20 and 30 counts. It might be that the IAC is not opening enough to let the air in so fuel and spark is there but the IAC is faulty. With a scantool we can set the IAC and see what it is doing. How did you set the IAC?

 

I set the IAC doing the following:

1) After cleaning the IAC, screwed the pintle all the way down and put back on the throttle body.
2) Turned ignition to ON and jumped the test port.
3) Waited 30 seconds to make sure IAC pintle fully extended.
4) Disconnected harness from IAC.
5) Turned ignition OFF and unplugged jumper from test port.
6) Had assistant turn car on and I adjusted the throttle plate set screw so that idle was at 500 rpm in drive with the EST bypass disconnected.
7) Turned the car off
8) Plugged in IAC, plugged in EST bypass.
9) Turned car on.

Is the above correct? Do I really need a scantool to do what you said?

 

No but the scantool helps. Did you just clean the IAC? What about the housing? I usually take the entire TB off including the TPI plate on the top and the IAC housing. Clean the TB and all the passages with brake cleaner and scrub the TB butterfly plates. Also clean the IAC housing.

Also when I clean the IAC I don't screw anything. I do steps 2,3 and 4 and then take it out and clean the pintle and spray the spring with brake cleaner.

The scantool is used to set the IAC when we have a bunch of mods and the idle speed changes from 500

 

why brake clean and not carb cleaner?

 

Because I use brake cleaner for a multitude of things and so I stock up that stuff but Carb cleaner is fine too.