Need to adjust idle...

[nesslar]

Here is a bad picture that I just stole of the idle adjustment screw. The center "peg" is actually the screw that turns? There is a nut down in there on my car that is to be left alone?
Does that screw just turn by hand/fingers? I have no screwdriver indent on mine. Thought I'd ask before messing around. I have a jumper and would like to raise the idle about another 200 RPM. Although the book says the system is designed to (on its own) "adjust over time" to suit conditions/age, it ain't happened here! Thanks!

[emac]

What year is the car???

[nesslar]

It's an '86. All I've read indicates turning that brass item in the center, which originally has a yellow plastic cap on it. Something doesn't add up. I may have read bad info. about this.

[emac]

You cannot adjust the idle on your car/

[ChrisBennet]

Originally Posted by nesslar

Here is a bad picture that I just stole of the idle adjustment screw. The center "peg" is actually the screw that turns? There is a nut down in there on my car that is to be left alone?
Does that screw just turn by hand/fingers? I have no screwdriver indent on mine. Thought I'd ask before messing around. I have a jumper and would like to raise the idle about another 200 RPM. Although the book says the system is designed to (on its own) "adjust over time" to suit conditions/age, it ain't happened here! Thanks!

You are on the right track. Some have screw slot and some have a hex (like a nut). Your picture shows the latter. I'm just guessing but I think it takes something like a 7mm socket.

As my professors used to say, "In the interest of completeness":

The DME (computer) controls the idle speed (set at 800 or 880rpm depending on year).

The idle adjustment screw adjusts where the engine would idle if the computer + idle stabilizer valve (ISV) didn't act to "correct" the idle.

To adjust the idle, with the car warmed up jump the test port and turn the screw to raise or low the idle. You want the idle speed with the jumper in, to match the idle you get with the jumper removed. I.E. so the car "naturally" idles at the computer set idle speed.

Sometimes adjusting the screw seems to have little effect on the idle. I don't know why. The last car I worked on acted that way.

I'm not sure, but I think that the DME may raise the idle when the air conditioning compressor kicks in.

-Chris

[Zef]

From 911 chips website

Idle Speed Adjustment

After fitting the 4K chip in your DME, your idle speed will be a bit higher than normal and may need to be readjusted down if it ‘hunts’ on start up or is higher than 900 rpm at normal running temperature. This can also happen on an '87 Carrera if the original chip is #1267355236. This is because in mid ’87, Porsche revised the programmed idle specifications from 800 to 880 rpm, and advanced the idle ignition timing by 6 degrees. To reduce the base idle speed if necessary to 880 rpm, adjust the idle speed screw on the throttle body by two to three turns clockwise. It may be covered with a yellow plastic cap, which will need to be removed. For a more exact adjustment, bridge B and C in the rubber test socket on the left side of the engine compartment (located behind the black removable cover) with a piece of wire, and adjust the idle speed to 880 rpm at normal running temperature. Properly adjusted, there should be no difference in idle speed with the jumper or without. Remove jumper when finished.

[nesslar]

emac:
I believe you are correct. That brass part is the throttle screw (and yellow cap). Part no. 930-606-161-00-M14 is the idle control valve that is an inline device which should do its work automatically. NOT adjustable I'm sure, and it's $175.00 or so. I wonder if mine is deficient. That would make sense. I'll have to clean it up at the connetions I think to see if that helps.
Interestingly, when I jumper B and C n the test port (warm engine) my idle is PERFECT and remains solid. So why is that? I think I might need a new ICV or better connections.
Then again, what is the harm if a jumper is left solidly in place?

[nesslar]

Syl,
Thanks. Yea, mine has a hex nut in there, and at lunch I took a closer look and it appears I have a little play there so I can turn the thing clockwise (not) or counter-clockwise (correct I am sure). I'll try it later. I need to get the proper socket....that would help! Also I'll order a new Pelican yellow cap to replace the one I quite effectively mangled.

[nesslar]

Yup! 7mm socket, ccwise about a turn and a half, ten mile drive, idle now at 850+/-. Just as I read originally around these here parts. Thanks all!