My 911 won't sustaing starting

[mickeywarner]

My 1981 Porsche 911SC the last two years during the winter months (after sitting for awhile) will only start for about 1 second or so -- always starts but won't stay running. Not a problem in the summer, although I do drive it more. I have gotten into the habit of starting the car every 4 or 5 days in the winter to keep it going. I'm leaning toward the "cold start valve" but do not wish to experiement as replacement parts ar expensive. Last week the temp was 90 degrees F and the car started just fine - today it's wet and 60 degrees F and it won't start -- if I keep trying time after time, it may start but it's just a crap-shoot. Any ideas?

Thanks in advance for any help --

[psalt]

My advice would be to try and find someone locally that understands CIS lambda, or buy a manual and do some research. Unfortunately the last version of CIS used on the 911 only lasted a few years, involved many changes and few understand how it works. The CSV only works when the key is in the "Start" position (cranking), it is irrelevent when the key is in the "on" position. If the engine fires for 1 second, then stumbles and stalls, it is usually a lean condition, not the CSV. It is a common problem with lamdba CIS 911's to develop a stumble after a cold start for a combination of reasons, but they can be tuned around the problem to fire and cold idle at a steady rpm. The problem can be a combination of vacuum leaks, mixture adjustment, ignition timing, spark plugs and lower air flow meter deflection from lower compression on a worn motor. If the car fires and immediately stalls, try disconnecting and plugging the vacuum retard line (gray hose at the back if the module). This will give a much stronger cold idle speed, but you will need to readjust the hot idle with the large screw on the throttle body. You can use you fingers once you find it (CW to lower idle). Once you get it running and the hot idle set, I would check the ignition timing at low and high speed, check the mixture with a dwell meter at the test port, then check for vacuum leaks at the injector sleeves with an unlit propane torch. Usually if you can wiggle the injectors and the sleeve O rings are original, they will be leaking.

If you are storing your car for the winter, it is a bad idea to start it and idle. Ideally, everytime you start the engine, the car should be driven at least 10 miles to get the oil up to temperature.

[Vincent Hill]

Originally Posted by psalt

My advice would be to try and find someone locally that understands CIS lambda, or buy a manual and do some research. Unfortunately the last version of CIS used on the 911 only lasted a few years, involved many changes and few understand how it works. The CSV only works when the key is in the "Start" position (cranking), it is irrelevent when the key is in the "on" position. If the engine fires for 1 second, then stumbles and stalls, it is usually a lean condition, not the CSV. It is a common problem with lamdba CIS 911's to develop a stumble after a cold start for a combination of reasons, but they can be tuned around the problem to fire and cold idle at a steady rpm. The problem can be a combination of vacuum leaks, mixture adjustment, ignition timing, spark plugs and lower air flow meter deflection from lower compression on a worn motor. If the car fires and immediately stalls, try disconnecting and plugging the vacuum retard line (gray hose at the back if the module). This will give a much stronger cold idle speed, but you will need to readjust the hot idle with the large screw on the throttle body. You can use you fingers once you find it (CW to lower idle). Once you get it running and the hot idle set, I would check the ignition timing at low and high speed, check the mixture with a dwell meter at the test port, then check for vacuum leaks at the injector sleeves with an unlit propane torch. Usually if you can wiggle the injectors and the sleeve O rings are original, they will be leaking.

If you are storing your car for the winter, it is a bad idea to start it and idle. Ideally, everytime you start the engine, the car should be driven at least 10 miles to get the oil up to temperature.

What this guy said plus you did not mention if you had Stabil in the Gasoline? Remember, no matter how many times you start it, you are not changing the fuel in the gas tank so other than draining the battery, Putting water and gasoline into the oil which also creates an acid that loves the metal used in Main and Rod Bearings, Starting it up all of the time and going no where is not good!

10 miles may heat up the oil when you have 5 Quarts, but in the winter time you need to go for at least 20 miles. Which is about what my wife drives every day and I still see the White traces that show the oil did not get hot enough.

When it is too rich it also will not start or run for more than a few seconds and go Pop Puff then stop.