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Registered
Join Date: Jan 2001
Posts: 400
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1.8 eratic idle
my 75 1.8 is now running but it starts fine but if i hit the gas peddle the rpm goes to 2500 and wont come down ... it only does this after it has been running for 5 min or so ( after aux air valve shuts off )
i am replacing all the vacume lines tommarrow if any body else has an idea of what to check so far i have checked the following : 1 throttle sticking .... no 2 idle screw ... no i can screw it all the way in and it keeps running 3 mixture screw ... no 4 vaccume leaks ... working on it 5 flapper sticking ... dont think so 6 cold start valve still squirting ... nope unpluged it TIA ------------------ scott thacher 75 1.8 running at last 75 under rust (fine german rust) |
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03-25-2001, 07:07 PM
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Senior Member
Join Date: Nov 2000
Location: Stuttgart FRG
Posts: 2,307
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Hello
Check the cold start bypass valve by pressing the hose togehter. Grüsse |
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03-26-2001, 06:02 AM
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914 Geek
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Check your Decel Valve. It's over on the right side of the engine bay. Haynes has a procedure to test it. It may be opening but not closing.
Check your timing. If it "sticks" such that the timing is advanced, the idle will be too high. Check for anywhere else that air could be going from before the throttle body to after the throttle body. --DD |
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03-26-2001, 09:02 AM
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Registered
Join Date: Jan 2001
Posts: 400
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well i thought of by passing the aux air valve ... was going to do that tonight
and dave i never woudl have thought of the decel valve but that is why you are the 1.8 god ( sorry to make you blush ) ------------------ scott thacher 75 1.8 running at last 75 under rust (fine german rust) |
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03-26-2001, 02:13 PM
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Registered
Join Date: Mar 2001
Location: Galt, CA, USA
Posts: 14
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I was having the same problem with my 75 1.8 so what I did is unhook the vacume line to the decel valve and plugged the line. Now I don't have that problem anymore and the engine drops to idle alot quicker, like a carbureated car. So far I have noticed no ill effects but if anybody knows of some problems with this procedure please post here.
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03-26-2001, 02:56 PM
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Registered
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The decel valve lessens the lean condition when the throttle is closed, shutting off the fuel supply, and the rpm are still high. Its purpose is to reduce NOx (Oxides of Nitrogen), the byproduct of a lean hot combustion. Plus your rpms will drop a bit more in between shifts.
------------------ Chris 75 914 2.0L |
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03-27-2001, 06:38 AM
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74 Porsche 914 2.0 
1975 Porsche 914 2.0L
