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Registered
Join Date: Jan 2001
Location: Iowa
Posts: 1,020
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Idle and a/c
My 88 Carrera normally idles at 800 rpm, but with a/c on the idle drops to 600 and it gets rough & lumpy. Is this normal, and if not, what do I do about it?
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08-01-2001, 05:53 PM
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Registered
Join Date: Sep 2000
Location: Shreveport, La.
Posts: 1,710
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I don't know if it is normal, but my '83 SC does it too.
------------------ Robert Stoll 83 SC 83 944 |
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08-01-2001, 05:55 PM
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Senior Member
Join Date: Jan 2001
Location: Left Coast, Canada
Posts: 4,572
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In my Ford pick-em-up truck, some little gizzmo kicks up the idle speed every time the a/c cuts in. The Porsche a/c is pretty crummy, but shouldn't it have something similar?
------------------ '81 SC Coupe (aka: "Blue Bomber") Canada West Region PCA The Blue Bomber's Website |
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08-01-2001, 06:17 PM
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Registered
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I believe the '88 (and my 85) have an Idle Speed sabilizing valve, or an ISV.
I am not sure how to go about checking it, but it sounds like yours is not working. When I turn on my a/c my RPMs actually go up about 50 rpm (i.e. a/c off it idles ~850, a/c on it idles at ~900). I am sure someone will chime in and tell us how to check the ISV. Good Luck! ------------------ Nick Hromyak '85 Carrera 7 & 9 Fuchs Havin' Fun in Sacramento |
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08-01-2001, 06:55 PM
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Senior Member
Join Date: Nov 2000
Location: Stuttgart FRG
Posts: 2,307
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Hello
I hope it was covered somwhere and has pictures. 1.) Check idle set switch on Throttle body This unit should lift the ignition to 10° BTDC at idle. 2.) Check trottle body switch Resistance should be 0 Ohm at idle postion 3.) Check for vacuum leaks 4.) Check the idle stabilizer unit Remove it with the wire hooked up and turn ignition on. It should open 50%. Early cars have a bypass adjusting screw on the Throttle body ( covered with a plastic cap ). You could set idle by jumping the idle stabilizer on the relay contact beside the ignition coil. Grüsse |
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08-02-2001, 10:25 AM
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Porsche
