Posting Vide- Idle Issue
 

Hello,

Is there a way to post a video here? I have a random idle issue, and would like you guys to give me an opinion on what it could be

I can email the video, if someone can please post it for me?

And give a description of the issue

YouTube, then post YT link here.

i dont have youtube account....

its ok.

It's free to sign up.

Idle issue.
 

Model/year please.

1980 911sc
 

Randomly when at a stand still like at a trafic light and in Neutral, the RPM's will go up and down (back and forth) by itself, until the car stallls and turns off.

I have to restart it and press on the gas to keep the RPM's at about 1-2,000 for about 20 seconds, until id idles steady with the RPM at 1X

Start the car and press down on the intake boot. If it goes away the boot is cracked around the rim. The area just above the hose clamps. Or a vacuum leak somewhere.
Try the boot first if it has never been changed.
My 2 cents.

There is no vacuum leaks anywhere and the intake boot is not cracked

this happens more often when the car is cold (10 min warm up then drive). It just happens randomly, when idleing at a traffic light

I thought the decel valve may not be working properly bringing the idle down slowly so the sensor plate does not bounce causing stalling

I think it may just be a dirty fuel distributor? may have to clean the injectors

I have similar idle issues only mine will race up to 2700 rpms when warm. I think the fuel distributor tends to stick, or my WUR is acting up. I was told to run Techron fuel injector cleaner through the system and it really started move crap thru the system as was evident fom the filter change and fuel pump acting up. I will watch this post for good advice from others. Idle issues abound!

Yes, my next step will be to run Rechron fuel injector cleaner as well

A slow hunting idle is usually a sign of a mixture that is too rich, usually either from a too low control pressure (WUR) or a too rich mixture setting.

Often a mixture is set rich to make up for a too lean condition at startup, which can be caused by a too high cold control pressure. As the engine warms up, the mixture becomes too rich.

When did this start? Was any change made to the WUR or mixture setting?

Have you had your fuel and control pressures, and your CO % tested?

Do you have an O2 sensor/lambda control? When the sensor relay fails the mix can become too rich. I don't have one but I think it is hooked up with the dome light. Is your dome light working?

That is one huge statement. How do you know?

I like what paulporsche says.

I had my mechanic(porsche specialist) examine the intake boot when the car was running, he didnt find any vacumm or oil leaks:)
He knows this car well

granted at the time, the car was idleing fine without hick ups

How about checking the auxiliary air valve. Looks like a small tiny pie plate. I believe it is for anti-pollution. There is a vacuum hose connected to it. Try removing it and and plug the loose hose with a golf tee or a big screw so it can't suck air. Restart the engine, warm it up, and see if the idle stabilizes.

This happened to mine, and I never reconnected it. The replacement part is a few $Hundred bucks. The golf tee was a dime and it came in multiple colors.
My idle is now rock steady on my 82 911 SC.