Idle hunts at 1200 RPM

[rsswesley]

Well here we go again. I did a tune up and the car still hunts at idle. It starts as soon as the car hits 1200 RPM. I am stumped but I have been reading all the posts I can about ICV and 02 sensor. Just one question how do you clean your ICV and when its cleaned how do you check to see if its working. I will also check vac leaks. Any other advice would be great.

[dtxscott]

Do a search on "hunting idle" and you will find a lot of pointers here. I had the same issue on my '89 Targa and it turned out to be a lean mixture at startup. I suspect I have a vac leak as well but will track it down later.

Please state the year and engine in your car so it will help provide better responses.

[Targa Me]

what year is your car?
If the ICV is working properly, with the ignition on, but the engine NOT running the ICV will vibrate; you can feel it with your hands.
Does your car have a miss as it runs or is it just a hunting idle?
I had a hunting idle once and it turned out to be the micro idle switch.
Another time I had a vacuum leak, check and replace the hoses and the leak turned out to be the gaskets on number 5 and 6 intake runners. The way I discovered that was to pull off the fuel injector harness one cylinder at a time (car running). I had noticed that the engine didn't run any worse as i pulled off those 2 injector harnesses.

[twistoffat]

To see if an Idle control valve is sticking, give it a tap to see if the idle problem alters in any way. If it does its probably sticking and needs to be cleaned. To be honest cleaning is a temporary thing. I cleaned mine but the problem kept coming back. Eventually I just got a new one

[Talewinds]

Can you describe your particular issue in detail more? There are a few idle hunt/bounce issues that people have that are caused by a number of things, but the difference is in the details.

[stlrj]

Originally Posted by rsswesley

Well here we go again. I did a tune up and the car still hunts at idle. It starts as soon as the car hits 1200 RPM. I am stumped but I have been reading all the posts I can about ICV and 02 sensor. Just one question how do you clean your ICV and when its cleaned how do you check to see if its working. I will also check vac leaks. Any other advice would be great.

It could be as simple as turning down (reducing) the base idle speed.

[Targa Me]

If the car was running fine before, i wouldn't turn any screws or make "adjustments" just yet.
Check all the switches and sensors first, one may be at fault.

[rusnak]

It sounds like a vacuum leak to me. If you remove the oil cap while the engine is hot and at idle, does it almost die? Vacuum leaks are usually numerous, so you should check and tighten everything to reduce the cumulative effect of multiple leaks.

[nesslar]

I am not sure I'm reading all this correctly...
First, he said the problem existed before a tune-up, and remains after. So I would adjust the idle; is the idle just too high? I mean, about 825 is good, no? 1200? Is that where you are? Too high. Smooth, sure, maybe, if it could be maintained, but it's not right. I had a spell once of hunting, and adjusted a few times (dropped the RPM) and all is well.....95% of the time, anyway.

[rsswesley]

I have an 82 with a 3.2 engine. The car usually site around 1000 rpm at idle. When it gets warm it will pulsate up to 1200 and thats when the hunting starts. When I first start the car cold it does not hunt. I have cleaned the ICV but it still does it. I take off the oil cap and the idle just changes a bit not a big difference. I have started tightening the lines and using propane to try and find a vacuum leak but i have yet to hear a change. I will check to see if the ICV valve is vibrating or sticking. If you have any more ideas i will take them all.

[Talewinds]

Ok, well, first things first. You need to set your base idle. 880-900rpm.

[rusnak]

If you have a Bentley service manual, it shows you how to check that the closed throttle switch is working, and if not, how to adjust it. You should hear a "click" as the throttle butterfly closes and you should see the switch open.

[stlrj]

Had a Porsche mechanic work on my 86 3.2 for a week after he installed the engine in my '74, trying to fix my fast idle hunt which included replacing the idle air control valve etc. and finally giving up.

Soon as I got it home, I lowered the base idle and it has never hunted since...hmmm.

Oh, I forgot to mention that when I raise the idle speed, it hunts all over again. I guess all my experience in the past, working on carbs came in handy.

[Canuck_Targa]

I have been reading the posts on idle bounce and idle hunting because my 84 does it between 800 and 1200 for about 30 seconds at start up, it has also done it randomly sitting at lights when the car is warm.
I figured I would start with the easy stuff first and clean the idle control valve. Removed it, sprayed the inside down with throttle body cleaner, used a dental pick to make sure the gate was moving freely and reinstalled.
Started it up and it leveled off perfectly. So keeping the idle control valve clean is a good start for trouble shooting this problem.

[stlrj]

Originally Posted by rsswesley

I have an 82 with a 3.2 engine. The car usually site around 1000 rpm at idle. .

No wonder! That's too high. The base idle for the early 3.2s are set at 800 and the late at 880 rpms.

Any higher and the hunt starts all over again.