I have a 82 911 sc with a common problem so I'm told. It happens to be a starting/idle problem that no one has been able to fix and hundreds of dollars waisted. This is the problem. If I happen to leave the car siting for a couple of days it will start right up like it use to but, if I drive it just down the street and allow it to cool off for a while it will take several cranks to fire it up. Starting hot is no problem it has been only if I use it as a daily driver will it give me these symptoms. To top it off when it does star and I rev it up it will cut off. Here is my finding so far:
Replaced spark plugs and wires, checked all injectors for spray pattern and checked all hoses. As for the Pressure
cold control pressure 1 bar
warm 3.5 bars
main pressure 4.7 bars
residual 2 bars Plus the csv voltage check ok.

Any help will realy be appreciated.

 

Dear Fellow SC,
I've had my SC for over 25 years in Malaysia and a couple of years ago that problem sprang up.I've checked with my SC register secretary in the UK and I was informed to carefully monitor the oxygen flow in the airbox which inadvertently causes explosions and in turn affects the airflow in the engine.Additionally, try not to rev your engine after starting untill you have reached optimum performance temperature.ie when the needle is at the top of the box at the temp gauge(as advised in the SC manual).As to the difficulty of starting the engine after having just used the car, I have the very same problem till this day.I believe the grade of fuel also plays a vital role as we here in M'sia are using standard 92RON unleaded fuel, not as of a higher quality as you guys over in the US or UK. I hope this helps a liitle but I will try to get more feedback from europe as it affects my car too and i'm curious as to the solution.

 

When I read this post, the thing that comes to mind is air/fuel ratio during the warmup period. Engines need more fuel when cold and that amount of extra fuel in the mixture decreases as the cylinder temperature rises. In a carbureted engine, it would be a matter of the choke being opened either too quickly or too slowly. In a fuel injected engine it would be the electronic equivalent of that, but exactly the same effect. With electronic fuel injection, I believe that the norm is to use a separate algorithm to enrichen while cranking and another algorithm to enrichen after the engine starts, based on coolant temperature (perhaps oil or cylinder head temperature in an air cooled engine). Sorry I don't know the exact specifics of the 82 SC but I've given the basic theory behind what is a likely place to start. If you have access to a garage with an O-2 meter that goes in the tailpipe, you may be able to see a very quick leaning out or a sustained enrichment, either one given an incorrect mixture. My first bet would be a defective temperature sensor, be it head, oil, whatever gives the temperature signal to the computer. Sounds like the engine "thinks" it is either warmer or cooler thatn it actually is. I am extremely doubtful that the condition has the least bit to do with fuel quality. Hope this helps. Post back when you solve it. That way everone learns. I know there are at least two who would like to hear an answer, possibly more.

 

Look at the distributor cap. It may be cracked

 

Ditributor cap problem should occur under any conditions, not dependant on ambient temperature. Go with mixture. One exception, cracked distrib cap is often worst in wet, rainy weather where the moisture enters the distributor and makes the spark jump around.