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Registered
Join Date: Nov 2005
Location: Virginia
Posts: 41
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High Idle CIS
I'm trying to diagnose a high idle issue on my 81 ROW 3.0 SC. It starts fine, but as it warms the idle creeps up, til it gets to 3000 rpm. Screwing the idle adjustment screw in all the way brings it down to about 2500. If it sits for 20 minutes, the idle comes back down, but after driving again will begin creeping up again. What components should I be looking at here as the culprit? Thanks for any input.
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04-30-2006, 09:16 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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WUR, AAR, AAV, decel valve, distributor, and air leaks for starters.
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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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05-01-2006, 04:33 AM
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Registered
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That sounds like a big enough leak to be a intake runner boot, or a hole in the main inake boot, time to get some ether and start spraying for leaks.
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2021 Model Y 2005 Cayenne Turbo 2012 Panamera 4S 1980 911 SC 1999 996 Cab |
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05-01-2006, 06:27 AM
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Registered
Join Date: Mar 2003
Location: Cameron Park (NorCal)
Posts: 779
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My '80 SC did the same thing. It was the AAR (auxiliary air regulator). Replaced it, and it ran like a champ.
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Mike '80 911SC Weissach Edition '87 325is '02 K1200RS |
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05-01-2006, 07:44 AM
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Somatic Negative Optimist
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Quote:
Idle adjustment screw in all the way? That doesn't sound right because it is part of the mixture adjusting process. Winterfarm: Get a Bentley SC Repair Manual and read, read and learn how the CIS-components work. The AAR would be the first thing to look at with high idle. You can do a search but why not get a Bentley? Without knowing the condition of your engine and what maintenance has been done, it's hard to diagnose. 
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD! 1995 seafoam-green 993 C2, LSD, Sport seats.  Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ". 
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05-01-2006, 07:54 AM
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1985.5 Porsche 944 2.5L Supercharged 
911 SC
Panamera
ME 262 (SOLD)
Colibri
Gas Mizer
Mileage King
Dog Bus
