Help With CIS Idle Adjustment

[niall]

Could anyone out there post a picture/graphics of the CIS system on a 3.0.

High lighting where the Idle adjuster is please.

I am currently having difficulty posting pictures.

[bigchillcar]

no pic, but hard to miss once you know where to look. driver's side of engine bay..it's a large silver screw, about as wide as a dime with a flat head insert..also a spring on the shaft. clockwise to reduce, counter to increase iirc..anyway, you'll figure that out easily enough. this idle screw faces out towards the driver's side of the car. also, you gotta make sure that the car is right at operating temperature to set it correctly (180 degrees), otherwise the cold idle speed will be incorrect. i'm sure someone will post a pic if you don't find it..it's in pretty plain view the left of the airbox..
ryan

[niall]

Thanks Ryan, yeah I found it. I suspected that was it, but I wanted to be certain.

[bigchillcar]

cool beans..

[diabolos88]

Turning it clockwise will fatten the mixture, turning it counter will lean it out. When trying to adjust the mixture you will insert your T handle in the allen hole then push down and slightly turn until you can feel the allen engage with the screw in the assembly. You don't wan to push too hard as this will cause the engine to die out. When you make your adjustments do so with little turns or you will end up in no mans land. Lastly CO adjustments should be done with a proper CO meter. By ear regardless of the best of them is not proper and will not yield maximum results. Your CO% target is 3.4% for best high performance. To pass smog, it should be set to just less than 1%.

[ianc]

Diabolos, you are confusing the idle adjustment with the mixture adjustment,

ianc

[diabolos88]

yep, I am! oops my mistake

[kach22i]

Go straight in from the top verticaly, not at the angle shown (just pointing to it).

You will need a 4" long 3mm allen wrench. The hole is just a hole, the adjustment screw is past the hole down there.

[Paulporsche]

kach221,

Remember, that is for mixture adjustment, which does affect idle speed. But the idle speed adjustment screw is the one described by ryan.

[kach22i]

Originally posted by Paulporsche
kach221,

Remember, that is for mixture adjustment, which does affect idle speed. But the idle speed adjustment screw is the one described by ryan.

I was following what "diabolos88" said, sorry about that.

I need to read what my Hayne's book says about this again - my mind is still on the topic.

[jmeany]

My son was tring to help. He took the 3MM wrench and turned it a "whole bunch of times" Now the car won't run. He used a pair of pliers to turn it. Now it is seized. What do I need to do to fix this? Does the engine need to come out? Do I need to remove the distributor and air box assy?

I am soo pissed...

[ianc]

jmeany,

Tough times. Are you unable to turn the screw with the 3 mm wrench anymore? Which way did he turn it, and can you turn it in the opposite direction?

ianc

[jmeany]

That is the problem he turned it counter clock wise & does not remember how many times. we did not feel any clicks I have tried everything I think.

[bigchillcar]

he may have leaned it out completely. sometimes they don't make clicking sounds, don't be overly concerned about that..however, you need to try to get it back into the slot and turn it clockwise, if possible. try to keep track of how many complete turns you do based upon his estimate. at this point, i'd just try and get 'in the ballpark' enough to get it running. mixture cannot be set accurately without a co gas analyzer. it's gonna be worth it to take it now to a shop equipped with one and have them 'baseline' your proper mixture setting, otherwise you're really shooting in the dark now. it shouldn't be too expensive and really needs to be done. some people claim success setting mixture by duty cycle, but they're pretty sharp at doing this. if you can't get it to turn, the fuel distributor may require removal at most, but certainly not the entire motor. what year and model 911? don't disown the son just yet.. do let him know that 'less is more' when it comes to adjusting mixture..an eighth or quarter turn can be significant..
ryan

[jmeany]

The 3mm hex screw is seized. I can't turn it right or left at all. I can't see what is going on under there because of my eyesight. I am thinking of removing the fuel distributer so that I can see it better and why the screw is bound up. How dificult is that procedure and is there a technical bulliten I can read about how to fix this?

You folks are wonderful. I am thankful that you take the time to help me wuith this issue.

-john meany

PS it is a 1981 911SC 3.0L

[ianc]

The 3mm hex screw is seized. I can't turn it right or left at all.

Well, if your young son was able to get it where it is with pliers, maybe you can try the same treatment (gently) to turn it clockwise again. Worth a try, but be careful...

ianc

[jmeany]

Your right and he did free it up just a few minutes ago... Now I am keping my fimngers crossed that we can get it close enuf to go to get the gas analyzer test and set up done.

[ianc]

Your right and he did free it up just a few minutes ago...

What? You're still letting him work on the car?

ianc

[MotoSook]

This must be your son's thread:

Ballpark adjustment of CIS idle mix

[bigchillcar]

jmeany..glad to hear it. i'm sure you can get it running well enough to get it to a shop with a gas analyzer now. glad you didn't have to pull the fuel distributor, etc. spend the little money now..it makes sense to get it baselined..very worth the trouble and expense.
ryan