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Unity Gain
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79 - Low Idle
Symptom: So for about a week at cold start my beloved shark would tach at 3k then drop down to 2k after normal warmup which is 1k higher than normal. Now at cold start she does not reach 1k and idles at roughly 300-400. Any suggestions where to start?
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Rick 79' 5-Speed -Black on Black A word to the wise is infuriating. 
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07-02-2015, 05:14 AM
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Maybe start with the AAV test.
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1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD** 
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07-02-2015, 05:40 AM
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Unity Gain
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Please tell me the music will play when performing this test !!!
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Rick 79' 5-Speed -Black on Black A word to the wise is infuriating.
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07-02-2015, 05:52 AM
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Registered
Join Date: Oct 2004
Location: L.A.
Posts: 48
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My US 82 Auto show that rpm but idles like a Cadillac. A little rough on take-off but very livable.
Tino |
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07-04-2015, 09:18 AM
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Registered
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Warm-Up Regulator
Hey Gryphon - Another possible reason for your idle issue may be the WUR (Warm-Up Regulator). It is responsible for setting your fuel pressure at the air/fuel control arm in the fuel control unit while the engine passes through a cold start to a warm engine.
One other comment - To perform the pressure tests needed to diagnose most CIS injection problems you must (buy or borrow) have the proper adapters, test gauge, shut-off valve and fuel line setup. J.C. Whitney used to carry a nice very reasonably priced unit. They are well worth the purchase if you intend to maintain an early Bosch CIS car. Here is one of the many discussions on the WUR - although normally factory set, they can be adjusted to tweak the final pressure setting. The Bosch CIS components and operating principle is the same no matter being installed on a Saab, BMW, Mercedes, Porsche, etc.... Pelican Technical Article: 911 Warm-Up Regulator Adjustability Keep Us Posted on your progress, Michael
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1984 928S - "Miss Purdy" 1987 911SC - "Frau Helga" 1986 930 - "Well Hung" 1975 911 Targa "Blue" Last edited by JK McDonald; 07-04-2015 at 02:28 PM.. |
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07-04-2015, 02:22 PM
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Registered
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CIS Pressure Gauge Set Up -
Here are a couple of photos of the CIS Gauge - and a couple of the tests being plumbed up. If the +12 volts supplied to the interior heater element is missing on your car the resulting fuel pressure regulation will not be correct and can produce all kinds of idle and run symptoms.
About half way down the page is a photo of the gauge set up - FUEL INJECTION TESTER FOR CIS-K-JETRONIC BOSCH SYSTEMS - Page 2 - Rennlist Discussion Forums This is a description of the WUR test procedure - Pelican Technical Article: Testing Bosch CIS Here is a Utube procedure for running a CIS pressure ops check - https://www.youtube.com/watch?v=h7drhxjJ2mg Michael
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1984 928S - "Miss Purdy" 1987 911SC - "Frau Helga" 1986 930 - "Well Hung" 1975 911 Targa "Blue" |
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07-05-2015, 05:34 PM
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2004 GMC YUKON
Elisha
