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Registered
Join Date: Dec 2008
Posts: 2
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1980 911SC O2 Adjustment ?
My 1980 911SC would run great but as soon as it warmed up it started to miss.
I had a stainless steel air box installed and it helped, then I found my catalitic converted was restricted so I removed the inside material which had melted. Now it starts right up and runs great but after it warms up there is a slight power loss and miss..like it may be getting too much gas or not enough ?? |
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12-07-2008, 12:53 PM
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*****
Join Date: Apr 2006
Location: Charleston, SC
Posts: 2,359
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Too rich? Does the idle hunt when warm?
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82 911SC Coupe Chiffon / Chocolate 9.5 JEs, 964 Cams, SSIs, Dansk Exhaust, CIS (SOLD) |
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12-07-2008, 12:57 PM
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Registered
Join Date: Dec 2008
Posts: 2
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yes, the idle is inconsistent when warm
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12-07-2008, 01:00 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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As mca implied, a hunting idle or, if you rev from idle and the revs swing too low and then try to come back up to idle speed, the mixture is usually too rich.
Are you also getting a miss? W/ a name such as ob juan, are you from a hot climate?
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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12-07-2008, 01:03 PM
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*****
Join Date: Apr 2006
Location: Charleston, SC
Posts: 2,359
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My initial guess would be that it is too rich. However, there are other factors that could also be at play such as your timing, vacuum leaks, etc.
If you don't have a gas analyzer or an air/fuel meter it may be in your best intested to take your car to a shop and have them test your mixture and check your timing. If you want to give it a go yourself, get the car nice and warm. Then turn the mixture screw (using allen wrench or mixture adjustment tool) SLIGHTLY counter clockwise. Do this until your idle stops hunting. Don't leave the mixture tool in place - turn a little and remove. Then give it some throttle, let the RPMS settle back down, then see if hunting idle is fixed. Repeat prodecure if idle doesn't stablize. Remember ... turn SLIGHTLY. Before doing anything, wait for some more feedback.
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82 911SC Coupe Chiffon / Chocolate 9.5 JEs, 964 Cams, SSIs, Dansk Exhaust, CIS (SOLD) |
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12-07-2008, 01:10 PM
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Nice marmot.
Join Date: Jul 2007
Location: Daytona Beach, FL
Posts: 118
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I had a bad (original, made in W Germany) O2 sensor relay on my SC that caused the warm idle to hunt from 900-1100 rpms. Replaced it and the warm idle plummeted to 400 rpm on the next start up. Adjusted the mixture and control pressure. Everything was out of whack. Now the idle is steady, although I still can't find the sweet spot for my control pressure. Also, check for vacuum leaks.
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Mike Dunn Daytona Beach, FL 1982 PORSCHE 911SC |
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12-07-2008, 08:21 PM
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