After I found this tidbit, I decided to try it this morning. I unplugged my IAC, and the car seems to idle fine now. It seemed like the IAC was pushing closed for some reason. It's a brand new unit also. But, that seems to be the problem.

I still can't turn on the A/C at idle or it will die, but that's a problem that can be fixed by tuning, right? Or is that simply a matter of the IAC not being able to compensate for the load, and should be fixed by the new IAC?

 

You should be able to turn your A/C on at idle and have it not die, no matter what. When you unplugged your IAC did it change your idle RPM? I would bet that all you did was band-aid the problem. Is it throwing codes?
Do you have a friend you can borrow a laptop from and scan your computer? It only takes about 30 min to set up the program and then you can delete it when you are done. This will tell you if any sensors are dead or reading inaccurately.

 

The idle came up a little, and it still dies with the A/C on. I've heard that can be fixed by tuning, but I'm also betting on it being that the IAC isn't moving and compensating.

I do have friends that I could use, however they're overseas right now. I'm trying to be patient until they get home so I can hook up freescan or datamaster on it and see what's going on.

 

The problem is that your idle should be a set RPM within the chip. When you unplugged your IAC it just is allowing air to bypass it and then your computer is forciing your car to run smoother because it cannnot stop the air from comming in so all it can do is add fuel to compensate. This is just a bandaid for your problem. I still say its the tuning for a couple reasons.
1) at a higher RPM its easier for the computer to smooth out. (exp. with no load)
2) With your new IAC plugged in it is probobly doing what it needs to but your timing is conflicting with the stock IAC. (I bet its something to do with vaccume at the IAC, but it should be resolved by tuning)

 

When you plug in your IAC, it will now be out of synch with the pcm. You will need to reset it.

IAC reset

-Depress accelerator slightly

-Start engine, then release accelerator pedal, run engine for 5 seconds

-Turn ignition "OFF" for ten seconds

-Restart engine and check for proper idle operation

 

shoebox:

Do I repeat those steps as necessary until it's right?

When I first put the new IAC in, it worked fine. I don't know why it wouldn't work now. Maybe because the car's been sitting a whole bunch??

 

I forgot to ask. Is your car throwing any codes?

 

No, no codes at all. I'm lost other than the fact that the car works without the IAC plugged in.

 

Ok, here's how it went.

Slightly depress gas. Started car, it revved up to about 2500 rpm. Let off gas. Car wouldn't stay running for 5 seconds. Restart engine, car starts, idles up, idles down to dying.

I am starting to think that the IAC is siezed. Unplug, car runs fine. With exception of A/C, but that can be worked around.

Looking for an IAC at this point.

 

You may want to try the reset again. Also it may take little time for the pcm to learn and get the idle speed correct-that's normal.

What happens when you start the car with the pedal slightly depressed, is it causes the pintle in the IAC to full extend. That kind of "zeroes it out". Then when you let off, the pcm will better know it's position. It may take some extended idling before it is smooth again.

It would be helpful if you had a scan tool to monitor the IAC counts, so you would have a better idea of what was happening.

 

Well, I'm working on getting access to a laptop that I can install datamaster on, so we'll see about that.

I tried the reset a couple more times, and each time the car just up and died when I released the gas. The only way it wouldn't die was when I would get back on the gas.

The IAC I put in was brand new, but sat open for quite some time before it was actually used. Plus, it got shipped cross country in the car via truck, then sat in my garage for another week or so before putting it in.

Once installed, the car ran fine, idled ok and all. It's just gotten worse to the point of not running. Could that just be the computer learning, so to say?

Here's another thought: What if I took out the IAC and manually upened it up some?

 

So if you just start the car normally, it won't idle? Are the IAC passages in the TB clear?

You have to be careful moving the pintle in/out manually. The gear can strip.

 

Yeah, everything was clear when I replaced it. Like I said, it ran fine when I first replaced it. Only in the past few times I've started it did I have this problem.

When I start it, it will idle up to about 900 rpm for a few seconds, then drop to about 600, then a couple seconds later drop again to the point of dying. Restart, repeat. The restart is a pain though. Nothing like the initial start. In initial start, it fires right up. On the restart, you've gotta crank it for a few seconds before she'll fire up.

 

The scan will probably help. You may have some other condition that is causing the IAC to over compensate. Visually check everything on your intake to be sure there is nothing loose or disconnected.

 

hey SHOEBOX, what should the IAC counts be.. i have a log and was wondering where they should be?