Cold Start Question
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Pro
Joined: Dec 2001
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From: Ellsworth, Michigan
Cold Start Question
Can anyone tell me what the symptom is/are for a failing cold start valve? Just yesterday I went to start the car in the morning and for the first time it did not start after the second try. Most of the time it goes on the first turn of the key. It did it today also. This only happens on the first start in the morning and then for the rest of the day it starts great (with a little rough running for one minute). I have replace in the last year: fuel check valve, fuel pump, injectors rebuilt, temp II sensor, and fuel injection relay. Any thoughts?
Racer
Joined: Nov 2001
Posts: 326
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From: Ventura California, where the girls are so fine.
My first thought would be the fuel check valve leaking or the injectors leaking pressure or a possible small fuel hose leak that you have not discovered yet. I had one hose leaking a very small amount but it would relieve pressure from the system. I have run my shark without all the cold start stuff connected to eliminate problems that I was having with it. When the cold start stuff was disconnected it started just fine every morning. First try. Now im in california where its fairly warm. Most mornings were in the 50's-60's. Usually the cold start valve helps most when its coooold out.
Oh, and by the way the problems turned out to be many leaking vacuum lines and a bad green wire. All else was fine. Hooked everthing back up to spec. My car starts first time in the mornings. Usually when it sits at work and I go out to lunch I will turn the key and it starts then dies. The second turn of the key it fires up and continues to run but has a rough running situation for about 10-20seconds. I havent pin pointed my problem yet but im close. It use to be much worse and wouldnt hardly start after sitting a few hours. but after going through and adjusting fuel pressures per the manual I got it to where it is today. I have never put on a new fuel check valve. I will do that soon just for ****s.
Chucker, it sounds as if we have the same problem after the car sits for a while after it has been running.
Oh, and by the way the problems turned out to be many leaking vacuum lines and a bad green wire. All else was fine. Hooked everthing back up to spec. My car starts first time in the mornings. Usually when it sits at work and I go out to lunch I will turn the key and it starts then dies. The second turn of the key it fires up and continues to run but has a rough running situation for about 10-20seconds. I havent pin pointed my problem yet but im close. It use to be much worse and wouldnt hardly start after sitting a few hours. but after going through and adjusting fuel pressures per the manual I got it to where it is today. I have never put on a new fuel check valve. I will do that soon just for ****s.
Chucker, it sounds as if we have the same problem after the car sits for a while after it has been running.
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Pro
Joined: Dec 2001
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From: Ellsworth, Michigan
Curt my car runs/starts great all day long after I get it going. I ordered a new cold start valve from 928 Specilists (God! am I glad that they exist!!). Dave and Geni have answered more questions for me then I can recall. I will keep you up to date on the progress of the cold morning starts. Good luck on your shark. Oh what is this green wire that I keep hearing about? When I got my shark there was a fried green wire in the harness that I traced back to a good spot (previous burn?) and then replaced. What does the "green wire" do and where is it? And then one more question.... Where is the cold start valve? I will need to know' so that when the new one arrives I will be able to replace it.
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Chucker - How high does it idle when it does start? If it is above 1000 then the cold start air bypass valve is working, but the cold start injector is not firing.
I found that you can run without the cold start air bypass valve, but it takes some cranking to start without the cold start injector working, even when the engine is warm.
Either the cold start injector is gunked up, electrically bad, or the cold start injector (thermo time) switch is bad. (The cold start injector only fires for a max 7 secs or so depending on engine temp; there is a small heater inside the switch that forces it off.) The thermo time switch is located to the left to the thermostat outlet facing forward.
Link: PorKen's Cold Start
I found that you can run without the cold start air bypass valve, but it takes some cranking to start without the cold start injector working, even when the engine is warm.
Either the cold start injector is gunked up, electrically bad, or the cold start injector (thermo time) switch is bad. (The cold start injector only fires for a max 7 secs or so depending on engine temp; there is a small heater inside the switch that forces it off.) The thermo time switch is located to the left to the thermostat outlet facing forward.
Link: PorKen's Cold Start
Racer
Joined: Nov 2001
Posts: 326
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From: Ventura California, where the girls are so fine.
To answer the green wire question. It runs between the distributor and the computer which is located just under the jump start terminal on the passenger side. The green wire plugs into a connector on the passenger side and then plugs into the distributor. This wire is very important. It basically controls the distributor. If this wire is hard and brittle and is cracking replace it. Cause sooner or later it will go bad on you and it will stop you dead in your tracks.
about the cold start valve (auxillary air valve) you can remove the rubber vacuum hoses from it (both sides) when cold and see if you can stick a screwdriver all the way through it. when cold you should be able to. when cold the valve is open. when warm the valve should shut inside and no air pass through it. its pretty basic. thats all that valve does.
Now you can also unhook the cold start injector but leave it connected to the fuel line. when the engine is cold try to start the car, with a friend watching the injector see if it sprays gas, if so how long. its that simple. if your auxillary air valve is open when cold and shut when warm and your cold start injector is spraying only when cold and doesnt continue in the on position or leak fuel then that system is working correctly. Odds are that all that stuff is fine. Not many times do those things have problems. its all pretty basic.
please let us know what you find. its all very interesting.
about the cold start valve (auxillary air valve) you can remove the rubber vacuum hoses from it (both sides) when cold and see if you can stick a screwdriver all the way through it. when cold you should be able to. when cold the valve is open. when warm the valve should shut inside and no air pass through it. its pretty basic. thats all that valve does.
Now you can also unhook the cold start injector but leave it connected to the fuel line. when the engine is cold try to start the car, with a friend watching the injector see if it sprays gas, if so how long. its that simple. if your auxillary air valve is open when cold and shut when warm and your cold start injector is spraying only when cold and doesnt continue in the on position or leak fuel then that system is working correctly. Odds are that all that stuff is fine. Not many times do those things have problems. its all pretty basic.
please let us know what you find. its all very interesting.
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Joined: Dec 2001
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From: Ellsworth, Michigan
Well this morning on a cold start it fired on the first turn of the key. On all of my other cars the 'Click and Klack' moto of "a broken part never gets better" has always applied. Until I bought this Porsche. Things seem to come and then they go away after I order the part. Well the new Cold Start Valve was order yesterday and now the prob. is gone.
