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How to setup CIS with no gauges

Here is how to set your mixture AND your cold control pressure with no gauges.

This will work on just about any CIS.. BUT you may not pass emissions.. though your car will be faster and driveability will go WAY up.

I did this and it worked PERFECT.. my car was a complete basket case before I did this... some will totally disagree with this and that is fine.. no reason to just post that you disagree.. this is just here for those that want to get their CIS up and running quickly and do not have gauges.. frankly, even if I had access to my gauge I would set it this way now.. its the best way to set it on an older car with vacum leaks and other things the factory did not plan for.. of course you should try and fix those things the best you can..

Okay.. first setting is hot run mixture.. you need to get your car HOT.. 180 degree's oil temp or better.

Okay, I am not going to go into how to adjust the mixture.. you can search for that.. but you need a 5" allen wrench.

Okay.. idle the car and turn the wrench all the way counter clock-wise. this should kill your car (stop when your car dies.. but DO NOT PUSH DOWN ON THE WRENCH!.. ). if it doesn't you got bigger problems and you need to stop and figure out why going FULL lean does not kill your idle... your idle should be about 900 rpm.

Okay. now, turn the mixture CLOCKWISE about 1 turn and see if the car starts.. if it does not, go half a turn until it does. Set your idle to 900 if possible.. if its unstable try going more clockwise.. get it stable.

Okay.. this is "my trick"... REV THE MOTOR a bit..

Let it idle

push down lightly on the wrench.. VERY LIGHTLY..

If the car revs more then you are too lean.. turn clockwise 1/4" turn. REV THE MOTOR.
Set the idle to 900 rpm

REV THE MOTOR

let it idle

Push down on the allen wrench.. if it revs more you are too lean.. 1/4 turn.


Keep doing this until when you push down on the allen wrench the car starts to die (too rich).

Ok.. now you are VERY close to proper setting.. the final tweek is to richen it up to the point where your engine starts to hunt.. (revs up and down) and then back off until it stops.. make sure YOU REV THE MOTOR between settings and give it time to clear up..


once you just back off slightly and you lose the hunt or up and down revving you are spot on. I have no idea what this will look like on a CO test but your car should be pretty quick ;


Okay.. now, assuming your fuel control pressure is good and you have no air leaks, your compression is good and all the other stuff is working perfectly including your control pressure regulator you will have a great idle at cold start. It needs to be cold out to find out and your car will need to be as cold as it gets in your area..

So... try and start the car..

It will do one of three things when you go to start it..

1) It will start and idle perfectly. (you are done, go test drive it)
2) It will start for a second and then stop.. and everytime you go to start it this happens.. starts and stops.. this means you are too lean at cold start..

3) it will start and idle horrible (maybe dies after 10 seconds or more) and while hangin out near the tailpipe listening your eyes will water and you probably see some black smoke.. it will probably hunt at idle.. (too rich)..

Now you need to shut the car off and not get it warm.. then you need to search for how to adjust your "WUR".. I hate that "word".. its not a warm up regulator.. its a control pressure regulator.. but whatever..

In a nutshell.. you will see a round circle on top of the "WUR".. it will probably be indented slightly.. if you are too lean you need to pound it in very slight increments.. like as in you can't see when it moves.. if you are too rich you get to remove it, open it up and pound it the other way.. might as well clean it out too.. it will be all full of aluminum "rust"..

anyway.. there are articles on how to make it adjustable if you want.. but this is out of scope here.. bottom line: adjust it until you can start the car cold and get it to idle.. if it hunts slightly I would just leave it.. it will clear up as the bi-metal strip heats and the control pressure is increased to lean out the car..

so.. this will cause a huge controversy and people will probably say very bad things about how silly I am.. but thats fine.. this works great no matter what anyone says.. and its especially good for older out of spec cars.. basically you are making your now out of spec POS run as best as a POS can.. and that's fine for now..

adios..

EDIT: also, be aware that when adjusting the cold pressure you will be throwing fuel into your intake from your cold start valve. this fuel will not burn completely.. it will lay in the intake.. YOU DAMN WELL BETTER HAVE A BLOW OFF VALVE at this point.. if you do not have one.. then do not do this.

After you get it started, you will see black smoke come out of your exhaust.. this is the fuel in the intake that is laying in there from trying to start it so many times.. it will go away as long as you didnt go to far on your adjustment.. now, at some point you should go ahead and disconnect your thermal time switch so your cold start injector stops spraying every time you turn your starter... if you do not you will get back fires in the intake and the exhaust.. be aware of this and dont let this "freak you out" and give up.. just understand that each time you go to start you are spraying into the intake and since you arent starting the car it just lays in there..
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Last edited by calling911; 01-16-2008 at 01:27 PM..
Old 01-16-2008, 12:14 PM
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You left something out...
If when you blip the throttle it drops below your set idle soeed and then comes back up you are still too rich. At this point it won't oscillate at idle but is still too rich.
You need to lean it out a little more so it settles down to idle without out dropping below your set idle idle speed and then coming back up.
Also, do this with the vacuum line disconnected from the deceleration valve if your car has one. Thats important because the deceleration valve will mask this effect to some degree.

You want to lean it out till it starts to run a little bit rough, and then slowly turn the 3mm allen wrench to the right for rich in small increments till the idle becomes smooth.
Stop there... thats it.

Also, with a 930 you want a very short 3mm allen wrench because the fuel head is only about 2" from the sound pad in the top of the engine bay.
Old 01-16-2008, 12:34 PM
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Quote:
Originally Posted by JFairman View Post
You left something out...
If when you blip the throttle it drops below your set idle soeed and then comes back up you are still too rich. At this point it won't oscillate at idle but is still too rich.
You need to lean it out a little more so it settles down to idle without out dropping below your set idle idle speed and then coming back up.
Also, do this with the vacuum line disconnected from the deceleration valve if your car has one. Thats important because the deceleration valve will mask this effect to some degree.

You want to lean it out till it starts to run a little bit rough, and then slowly turn the 3mm allen wrench to the right for rich in small increments till the idle becomes smooth.
Stop there... thats it.

Also, with a 930 you want a very short 3mm allen wrench because the fuel head is only about 2" from the sound pad in the top of the engine bay.

I disagree with this but don't want to turn this into an argument about whether I am right or not.. Last time I checked Bosch wasn't seeking my expertise out.. so your mileage may vary.
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Old 01-16-2008, 01:20 PM
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Originally Posted by JFairman View Post
Well... we can agree to disagree then

That said, if and when the day arrives that you've had more experience tuning CIS, L-jetronic, and multiple weber carburator setups, by ear... and worked on German street cars and Porsche race teams for a living.. you may learn more.
here it comes.... lol.

EDIT: My instructions stand. Suggest they are followed very carefully.. I'm done here.. UNsubscribed.
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Last edited by calling911; 01-16-2008 at 01:55 PM..
Old 01-16-2008, 01:49 PM
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You can always try this thread
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Old 01-16-2008, 05:39 PM
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Old 01-16-2008, 07:01 PM
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calling911 you are tougher than i by putting this subject on the floor.

i have mine set more like JFairman said. it is set to the edge of the drop in idle when you let off the throttle. it may be on the rich side, but that is better than lean. so until i can put an analyzer on it, thats all i can do

i dont agree with banging on the WUR with out checking the pressures first.
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Old 01-18-2008, 04:06 AM
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I have owned several 911's with CIS (1973.5T, 1974 and 1979 SC) over the past 30 years and have known most of the great Porsche mechanics in the Atlanta area. The idea of "knocking" in the WUR pin to enrichen has been a taboo with every mechanic. It is a quick but incorrect fix as opposed to adjustment. Adjustments can be made to the WUR without knocking in the pin. Of all the CIS components the WUR can be the most troublesome and frustrating to deal with.

The method presented here on adjusting the fuel mixture setting to dead lean and building back is interesting. Many of the experienced mechanics who cut their teeth on CIS can adjust without a meter just on "feel" alone. I spent all day adjusting my mixture on my 1973.5T by driving then stopping to adjust through all the ranges and temperatures. One mighty click at a time. And I was very satisfied with the results.

I for one would hesitate to attempt this because of possible backfire and damaging the airbox although I have a pop off valve. Besides, the suggestion was that everything else has to be working perfectly before attempted.

My 2 cents

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Old 01-18-2008, 04:55 AM
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C Is

Hello, I havea 10/74 S with CIS. It only idles smoothly in one position on the adjuster. If to rich it oscillates.

So it seems my car is "easy" to adjust, that way. But when I run it richer, it goes like stink in the upper rev-band. When I adjust it back to ideal idle, it hurt the top end...

The engine runs higher compression and a 2 by 2 sports exhaust. When I added another 5 cm hole in the airbox tings impoved a litte.

Should I try a sports filter as well and add another 5 cm hole in the arbox?

Or do I have some issues with my CIS?

Thanks for inputs...

Ole
Old 01-19-2008, 01:11 AM
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not all CIS systems. i think you would need to disconnect the O2 sensor on some of them. me i pay less than $40 to have a pro mechanic hook it up to his sniffer.

i love the "chip on the shoulder" attitude with your advice. nice touch.
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Old 01-19-2008, 09:51 AM
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Like Harry says, it's been covered before, okay?

CIS Idle Speed and Mixture Setting Without an Analyzer

Slightly richer would be my preference, okay?
Octane and timing might give slight variations, OKAY?
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Old 01-19-2008, 10:12 AM
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Quote:
Originally Posted by Sunroof View Post
Adjustments can be made to the WUR without knocking in the pin
Please explain.

I have a high cold control pressure and knocking the pin was going to be my adjustment method.
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Old 01-19-2008, 10:17 AM
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Now put it on an analyzer and see where you're really at.
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Old 01-19-2008, 10:45 AM
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I guess I should retract some of what I said before about the CO adjustment since most of my experience with CIS is on old 4 cylinder BMW's and more recently with a 930 which runs a bit richer when under boost anyway with the type of control pressure regulator thats in it.

I can see how an SC or any normally aspirated CIS car would be a little more powerful with the CO set a little rich at idle.

I like to have a smooth stable idle if possible though, so without having the fuel head modified to be richer at full throttle (if anyone does that for a normally aspirated CIS car) maybe the way to go for an SC is to set it rich like you guys say and live with a surging idle, and/or have the O2 sensor and lambda system in good working order so that hopefully/maybe the pulse frequency valve can override the rich base setting or correct it at throttle positions other than full throttle and still have a good idle.

That is if there is a throttle position sensor on the SC that puts the lambda system into open loop mode (taking it out of the loop) at full throttle as it does on a 930.

Thats what I like about the old Bosch L-jetronic... it's so easy to tap into the engine temp sensor wire (in series) with a 10,000 ohm linear taper potentiometer and have that in the car somewhere and richen up the fuel mixture at will by turning the knob clockwise to increase resistence.
All the temp sensors on L-jetronic work by varying resistence to ground on a signal from the ECU. The airflow meter does it in a similar way too.

At about 2/3 turn to the right on the potentiometer you're making the ECU think it's around 10 below zero out, so it lenghtens the injector dwell time delivering alot more fuel.
You can also hook up a multi pole 12 volt relay to the throttle position switch so you can have that system only work at full throttle too. That way the throttle position switch still triggers the origonal fuel enrichment that it origonally did... you can also have it turn on a nitrous system too, but thats getting a little crazier... and I know this is a bit off the CIS topic.

...sorry about sounding like a know it all with an attitude before.
at least i admit it.
Jim
Old 01-19-2008, 11:35 AM
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Craig (mca),

You still waffling on this?! I know...it's scary.

Knocking the plug seems to be the best way to lower your cps. You can also change the relationship between cold and warm by adjusting the screw behind the popoff brass cap on the bottom of the WUR. Note: this is not found on all WURs.

Someone posted that he accomplished this by bending the lever arm inside the WUR. Apparently they tend to flatten out, I guess from metal fatigue, over the years.

Getting the right warm cp doesn't seem to be much of a problem, as you can probably set the mix to suit whatever it is once warm. The problem seems to be then getting the right mix for cold starts and warmups without popping.
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Last edited by Paulporsche; 01-19-2008 at 11:48 AM..
Old 01-19-2008, 11:39 AM
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Quote:
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Craig (mca),

You still waffling on this?! I know...it's scary.

Haha ... kinda waffling. I took her to a shop last week to check mixture and look for vacuum leaks.

Surprisingly the mixture was still pretty lean. No leaks.

I haven't driven her since due to the crappy rainy weather of late.

I will keep you posted though.
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Old 01-19-2008, 11:57 AM
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Did they richen the mix? What % was it?
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Old 01-19-2008, 12:08 PM
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Did they richen the mix? What % was it?
yeah, richened ... didn't see the % as i was trying to stay out of the way a bit. i wasn't familiar with the guage they used. it was not digital like the others i have seen / used.
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Old 01-19-2008, 03:04 PM
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I would ask them so you have a baseline for any future work. Also, how are your symptoms now?
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Old 01-20-2008, 10:32 AM
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Same symptoms. I can call and see if they remember.

I am going to have to punch the plug ... some day!
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Old 01-20-2008, 05:03 PM
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