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Registered
Join Date: May 2005
Location: davis
Posts: 174
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CIS Question
Does anyone have an idea why my 82 SC idle raises about 200 rpms when the oil temp reaches 200 degrees? My auto meter a/f meter used to fluctuate between red and yellow at part throttle, but lately it stays in the green. full throttle = almost full green then it falls back but stays green. I'm suspecting one of the many sending units,air valves cold starts etc. Any help is appreciated. P.S. the engine has ssi's and a k/n air filter, good power and the gas mileage is lower since this change in the a/f ratio.
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06-01-2005, 08:07 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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Could be the higher ambient temp and lower air density of the spring has it running a little rich.
Do you know how to lean it out? Else...do a search. Welcome! (I see it'syour first post) |
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06-01-2005, 08:13 PM
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Registered
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Location: davis
Posts: 174
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thanks . to lean out by turning the allen on the fuel dist.?
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06-01-2005, 08:16 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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Yes, turning the idle mixture counter clockwise will lean it out, but make sure that's you problem first. Did the condition just appear w/o other changes?
Try pushing up on the airplate very slightly when the engine is idling. If the idle increases, you are running lean...if it sputters or the idle slows, you are running rich...it's a quick field check, but it works well enough. Be very careful not to make more than one change at a time to the CIS. Too often people try a number of things, then get it all screwed up...then they can't get it back to how it was... A 1/8 or 1/4 turn at a time...you can do it with the car running if you are good and have a soft touch..else, shut the car down, turn and start...doing leave the 3mm wrench in the hole. |
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06-01-2005, 08:23 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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06-01-2005, 08:24 PM
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Registered
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Location: davis
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that good imfo and i'm going to try it tommorrow. what I noticed the most is the engine doesn't back fire during de-celleration like ssi equipped sc's. mine in particular. Right now it feels more like a motronic fuel system? But i'll try the tips and get back to you.
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06-01-2005, 08:33 PM
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soux,
this field test is news to me..do you have a link to more support information about it? i'm anxious to try and see what happens on my car..where did you learn of this? ryan
__________________
To the memory of Warren Hall (Early S Man), 1950 - 2008 www.friendsofwarren.com 1990 964 C4 Cabriolet (current) 1974 911 2.7 Coupe w/sunroof 9114102267 (sold) 1974 914 2.0 (sold) |
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06-01-2005, 08:43 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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Ryan,
That check is not new. Most of us know about it, and we have been doing it. I adjusted a 78 SC track side in less than 10 minutes. With a 3mm screw, I could lift the airplate up without taking the airbox cover off...with a little rotational force while lifting...immediately I know the car was running lean (it was idling). I had my timing light handy (I always have it in my tool bag) and I set the timing and fuel...and off he went. The car felt better on the track and when the owner drove it on the street...he definitely was happy with it. I don't recommend the above 3mm wrench trick if you are not comfortable with the CIS. |
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06-01-2005, 08:53 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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I should add...the field check is simple..we know that more fuel goes to the injectors when the fuel distributor plunger rises right? So with a little movement of the airplate (not enough to clear the throat of the venturi...there should be more fuel to the injectors as the FD plunger moves up slightly (you would be doing the same using a 3mm wrench turning CW). If that results in a higher idle, it was lean...if the mixture is at the limit of richness...the idle will slow or stumble..too much fuel.
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06-01-2005, 08:57 PM
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excellent. not as comfy with the cis as you, but comfy enough to contribute in the areas of knowledge that i do have of it on the board the past 3 years. i have the proper tools, can chack pressures, adjust mixture, set timing, adjust points, replace components..yada yada..but honestly had never come across this quick field check. yep, it makes perfect sense and i'm grateful to have stumbled across it even at this late juncture..i feel like a lucky punk..
 ryan
__________________
To the memory of Warren Hall (Early S Man), 1950 - 2008 www.friendsofwarren.com 1990 964 C4 Cabriolet (current) 1974 911 2.7 Coupe w/sunroof 9114102267 (sold) 1974 914 2.0 (sold) |
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06-01-2005, 09:29 PM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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"Well, do you?"
 
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06-01-2005, 09:34 PM
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"who's WE sucka..?"
__________________
To the memory of Warren Hall (Early S Man), 1950 - 2008 www.friendsofwarren.com 1990 964 C4 Cabriolet (current) 1974 911 2.7 Coupe w/sunroof 9114102267 (sold) 1974 914 2.0 (sold) |
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06-01-2005, 09:41 PM
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1974 Porsche 911 2.7
