|
|
|
|
| Author |
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
It's that time of the year AGAIN! (CIS)
Get ready for the CIS start-up questions to come rolling in.
It's discussed every year in the spring and in the fall.... What happens during this time of year? Take a guess...go ahead... |
||
10-06-2004, 09:44 AM
|
|
|
Registered
Join Date: Aug 2003
Location: Denver
Posts: 1,242
|
I'm new here so clue me in. Are you suggesting that people begin to have problems with their CIS in the fall/winter? Is so, I'm guessing it's WUR related?
__________________
1999 996 C4 Cabriolet 1997 BMW M3 (Hail) 1985 928 S (Sold) 1982 SC Targa (Sold) |
||
|
10-06-2004, 09:56 AM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
That's a part of it....why?
|
||
|
10-06-2004, 09:58 AM
|
|
|
Registered
Join Date: Aug 2003
Location: Denver
Posts: 1,242
|
Cold Start Valve would be the other part. Colder temperature being the likely cause. But, I have a feeling this is a little more technical of a question?
__________________
1999 996 C4 Cabriolet 1997 BMW M3 (Hail) 1985 928 S (Sold) 1982 SC Targa (Sold) |
||
|
10-06-2004, 10:01 AM
|
|
|
Registered
|
Extended temperature changes make things expand, crack, stretch, shrink & corrode. I've observed the same phenomena during the seasonal changes as well.
__________________
Warren & Ron, may you rest in Peace. |
||
|
10-06-2004, 10:16 AM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Yes! The ambient conditions are changing! The CIS sub-components, such as the WUR and the AAR are being affected and they will start to work differently now that that the morning temps are so low. What was fine when the morning temperature was 70 is now not so good at 40 degrees. Some of you are lucky and your WUR or AAR are not so finicky. I have heard reports of finicky CIS engines when they were new from their original owners. It's unreasonable to expect our 20+ yr old cars to be consistent over the wide temperature range.
Think sticky AAR valves, stiffer WUR springs and system pressure spring, harden diaphragms, vacuum leaks, internal air leak, etc,.. Some of the later CIS cars (80-83) with the Lambda circuit should be able to compensate better. But even those cars have a limit to how well the frequency valve can help. So don’t start fooling around with the CIS components, when all you need to do is richen up the idle mixture. Why richen? The cold air is more dense, so if your CIS was set up to idle well cold during summer months, with the idle mixture on the lean side…what happens now? It’ll be too lean to idle well. Crap our CIS engines love to be rich, right? Denser cold air is nothing new and shouldn’t shock anyone, but when our cars start to act up, the whole Porsche wrenching mystique gets us thinking the worst…. Last edited by MotoSook; 02-24-2006 at 08:15 AM.. |
||
|
10-06-2004, 10:29 AM
|
|
|
|
Registered
|
Quote:
__________________
Warren & Ron, may you rest in Peace. |
||
|
10-06-2004, 10:33 AM
|
|
|
Registered
|
Funny, I just gave my mixture screw a little tweak this morning (richer). It fired right up into a nice idle. Also eliminated the lean surge it had yesterday.
It's getting cold here in NJ, but my 3-mm allen wrench was ready for it. Ed
__________________
Basically, I'm One Giant Train Wreck. http://community.webshots.com/user/evill914 |
||
|
10-06-2004, 10:37 AM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Right on, Rick.
I should also say that my "leaner" example above is not to be taken for granted as the only possibility. As the spring in the WUR and the diaphragm age, the WUR can cause a rich or lean idle condition. If the AAR takes longer to close because the crud in it is making the vane sticky, but the WUR is working good...then it may lean as the engine warms... There are several combinations of things that will cause those small hassles, but the thing to keep in mind is the ambient conditions! Last edited by MotoSook; 04-06-2005 at 09:07 AM.. |
||
|
10-06-2004, 10:47 AM
|
|
|
MAGA
Join Date: May 2004
Posts: 10,762
|
Hey Souk are you a CIS expert? My recently acquired 79 SC is nearing installation of it's engine that I just did a top o'haul on. While cleaning up the CIS system I noticed that it has a newer WUR (with a rebuilt sticker on it) that does not have vacuum ports on it. After searching I have concluded that it is a newer post '79 WUR. The newer cars used an O2 sensor to enrich the mixture during acceleration. Do I run the risk of engine damage if I drive the car w/ out the proper WUR? Can I assume that the acceleration will not be as good as it should be?
I posted a thread on this a couple days ago and no one that responded seemed to know whether or not this is a big deal. Just fishin for suggestions. I will buy a new WUR if neccesary. But I would at least like to start this thing up this weekend.
__________________
German autos: '79 911 SC, '87 951, '03 330i, '08 Cayenne, '13 Cayenne 0% Liberal Men do not quit playing because they get old.... They get old because they quit playing. |
||
|
10-06-2004, 11:45 AM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Tim,
In a pinch I installed an 82 WUR on my 78 engine. I've got the idle mixture turned to rich, and I'm running 32 degrees total advance. With all the projects I have going on, I have not rebuilt the two 78-79 WUR that I have on the shelf. So my car has been running with the non-stock WUR for a long time. I've even driven the piss out of it at the track. The engine temperature was not unusual so I assume that my set up is fine. CHT readings would help me, but I'm not worried about it. And for just the weekend....don't worry about it. My engine runs strong, cool and accelerates just fine. |
||
|
10-06-2004, 12:08 PM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Quote:
|
||
|
10-06-2004, 12:10 PM
|
|
|
|
Registered
|
Quote:
__________________
Bill G. '68 911 Ossi Blue coupe |
||
|
10-06-2004, 12:13 PM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Not recently Bill, but I'm to be back on the road in a couple weeks
 and not in your area
|
||
|
10-06-2004, 12:14 PM
|
|
|
Original Owner
Join Date: Dec 2002
Location: San Antonio, Texas
Posts: 1,905
|
Re: It's that time of the year AGAIN! (CIS)
Quote:
I hear you can set mixture without a fancy pants gas analyzer just by bending over and sniffing the exhaust gases. Are you going to demonstrate this before or after the cart race Sunday?
__________________
tsuter 78 911SC Turbo Targa Thaaaats Right!! |
||
|
10-06-2004, 03:16 PM
|
|
|
Registered
Join Date: Sep 2003
Location: Valley City OH
Posts: 367
|
I'm in Ohio and mine starts and runs fine
|
||
|
10-06-2004, 03:27 PM
|
|
|
Registered
Join Date: Nov 2003
Location: Winchester, Va
Posts: 666
|
n00b question,
SO where is this mixture adjustment screw exactly.? Pic please. Tim
__________________
Tim 82 SC 90 C2 Yasowatt |
||
|
10-06-2004, 03:31 PM
|
|
|
Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
|
Suter: My nose is out of calibration
But if you want, I can tune that beast of yours in trade for a drive jlandeth: you are one of the lucky ones. I don't usually have to fiddle with mine, but I know when it changes. There are more cases of the lucky ones than there are the unlucky ones. Tim: If you search "idle mixture screw" you will find a lot of pictures. Some of which I posted for "n00b's" such as yourself If you do find it, link it to this thread...or I'll do it later....later later.
Last edited by MotoSook; 10-06-2004 at 03:42 PM.. |
||
|
10-06-2004, 03:39 PM
|
|
|
Hopelessly Addicted
Join Date: Jan 2003
Location: Central PA
Posts: 314
|
Mine is running better now in this colder weather. Must have been too rich all summer long.
__________________
'81 SC Targa '86 944 '49 Ford F-3 '13 Yamaha FZ-1 (Adrenaline Machine) 
|
||
|
10-06-2004, 03:46 PM
|
|
|
Registered
Join Date: Nov 2003
Location: Winchester, Va
Posts: 666
|
__________________
Tim 82 SC 90 C2 Yasowatt |
||
|
10-06-2004, 04:04 PM
|
|
1985 Porsche 911 3.2 (Still in the stable)
1993 BMW 740 IL (Sold)
1985 Mercedes 380 SL (Sold)
1992 Harley Davidson Fatboy (Sold)
1971 Mercedes 280 SL (Currently being restored)
