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Porsche Addict
Join Date: May 2014
Location: San Clemente, Ca
Posts: 1,141
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No Idle At High Altitude
To start with, I'll admit to being a complete ignoramus about CIS. My car wouldn't hold idle at 3,000 - 4,000' elev. today on our drive through southern California's San Diego mountains.
Should I just drive at sea level? Just kidding. Help me to understand what is going on. Thank you.
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Lawrence - 1986 911 Carrera Coupe Grand Prix White 1959 Land Rover Series II 1962 Volkswagen Sedan Ragtop 1959 Porsche 356A Coupe 1971 Porsche 911T coupe Last edited by Larmo63; 06-06-2020 at 04:35 PM.. |
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06-06-2020, 02:37 PM
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Still here
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Thinner air with the same or about the same fuel means it runs richer since it makes sense that the metering plate doesn't fully compensate given it's proportional to the area not volume.
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06-06-2020, 02:44 PM
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undervalued member
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when was the fuel filter last changed?
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78SC PRC Spec911 (sold 12/15) https://www.youtube.com/watch?v=f7I6HCCKrVQ Now gone: 03 996TT/75 slicklid 3.oL carb'd hotrod 15 Rubicon JK/07.5 LMM Duramax 4x/86 Ski Nautique Correct Craft |
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06-06-2020, 05:31 PM
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Porsche Addict
Join Date: May 2014
Location: San Clemente, Ca
Posts: 1,141
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I just did the fuel accumulator, I have a new filter in storage that I didn't know I had.
Would that make a difference?
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Lawrence - 1986 911 Carrera Coupe Grand Prix White 1959 Land Rover Series II 1962 Volkswagen Sedan Ragtop 1959 Porsche 356A Coupe 1971 Porsche 911T coupe |
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06-06-2020, 06:54 PM
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Still here
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JB has been a CIS outcast for a long long time, something to do with a stern master or something.
No, you are not short of fuel. |
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06-06-2020, 07:13 PM
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Porsche Addict
Join Date: May 2014
Location: San Clemente, Ca
Posts: 1,141
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I thought it had more to do with air pressure/oxygen.
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Lawrence - 1986 911 Carrera Coupe Grand Prix White 1959 Land Rover Series II 1962 Volkswagen Sedan Ragtop 1959 Porsche 356A Coupe 1971 Porsche 911T coupe |
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06-06-2020, 09:11 PM
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Still here
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The metering plate can't compensate completely for the lower air pressure so resulting in a rich condition, is my understanding.
This video (which is one of Raw'hide's favorite) explains the CIS operation very well. |
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06-06-2020, 09:58 PM
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Registered
Join Date: Apr 2013
Location: SoCal
Posts: 893
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At least with carbs they run when up at 7k ft just not well. Turn into on off switches. And are kinda grumpy at idle.
My new engine is efi. All the fun stuff is sea level to 7k + here |
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06-06-2020, 10:16 PM
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