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Discussion Starter #1
Any idea why this is happening, and how I can fix it? It's idling at 700 rpm, and I can't keep the thing running at stop lights.

There's apparently no way to adjust the idle speed? That's crazy.

Help? Thanks!

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Thats What She Said
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There is a set screw that will adjust it a bit but the ECU learns.

Does it actually die or does it just feel like it will die and you give it some gas?
 

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Discussion Starter #5
It will eventually die (maybe 20 seconds or so after stopping), about 3/4 of the time. No error lights.

It was idling just fine, around 1000 - 1100rpm before changing the battery. Why would it change? I've never seen that happen before.

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The idle at 1000 was incorrect, correct is 750+-. You killed the computer memory with the battery disconnect and now it is trying to reestablish the correct speed.

The dying?-you fix something to stop it, commonly a vacuum leak that you may well have had all along. Why the too high idle.

You haven't been able to set idle speed in 20 years and doing so is a violation of the law, it raises emissions.
 

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Discussion Starter #7
Thanks for the feedback! Yes, "something" is wrong, and has been for a couple of years...see my other post (and please comment...I need help!).

But I guess if this idle speed is correct, and there's no way to set it higher, then this thread is closed...since technically this isn't a problem that needs fixing.

So I'll see you guys over in my other thread as I try to fix my bouncing speedometer.
 

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The idle speed IS correct, but you can try something based on this understanding.

The IAC is there to adjust to the correct speed the PCM tells it to. It can normally have to increase to get that speed or decrease and the former is the way the cars are set to do from the factory. What determines that is how fast the car idles when warm with the IAC plug DISCONNECTED, and OEM has you adjust the TB butterfly to get about 700 rpm to let the IAC only bump up a very little to be right at 750. It allows the IAC to have more of a control range.

The problem being this..............older cars will not idle as fast as younger ones because the ring seal has dropped due to engine wear. Meaning they are more subject to try to die while the IAC is trying to make up for say the a/c just coming on to kill the motor. I had fits on that with one of my older cars.

The 'fix' was to unplug the IAC and then readjust the butterfly to have the engine idle slightly HIGHER than the 750 rpm, to then make the IAC adjust the other way. That means the idle during active IAC adjusting is higher than before to help the engine to not die. Maybe adjust to 800-850ish. then plug the IAC back in to do its' thing bringing the idle to the correct level. Except now it is working in the opposite direction, as long as internal range is still in it then it can do that all day long. It's only when you hit the end of range by moving the idle speed with the butterfly too much that you get a code for it.

It cured my issue almost 100%, the car does not try to die any more. It IS easy to go too far, the engine idle will begin to hang too high and there can even be safety issues so you go a very little bit upward on the butterfly adjustment at a time. I use a half turn max at a time. The butterfly has an adjustment screw for it somewhere on the TB, some have to drill to expose the screw. '01 though does not.

Be careful, this idea in the hands of an idiot can be dangerous, but it DOES work, mine has been running like that for years now. Do NOT try to get up around 1000 or higher again, it should pop dtcs all over the place when the IAC runs out of range.
 

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Discussion Starter #9
Thanks @amc49. I'll have to do some digging to understand where the IAC plug is and where the TB adjustment is on my '01. But as it's been *hot* here, I probably won't do it soon. :)

However, I *did* (for better or for worse) measure out a vaccuum hose just a smidge longer than the idle stop screw and pressed it on top of that screw, so effectivly it's longer (adjusted out) now. The first try had my cold idle at like 3k; kept cutting it down until now it's about 1k. It is a bit risky, as you mention...the idle hangs pretty high between shifts and when taking my foot off the gas and coasting, but I'm super-aware of this and a good driver so I'm leaving it this way for now.

The crazy thing is, the idle will *still* get pulled down to the 750 range on occasion (probably the PCM really trying to do its job), and once there, the slightest tap of the gas will cause the speedo needle to jump and the engine to die (referring to my other thread)...but at random.

But at least now I can come to a stop about half the time and not worry about it dying; the other half of the time it may or may not die on it's own or die when I give it gas. Crazy. :)

I updated the other thread too.
 

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Be VERY careful there, you are in the land of car accelerating by itself now............now you realize how the idle gets pulled in whatever direction the PCM needs to get back to 750 or so. The IAC can go either way.

Mine is such that none of that happens, there is zero hanging idle, I worked on the rest of the car to get that situation however.
 
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