Stalls until engine is warm.

[RSWiser]

When I start my car and for the first 3-4 minutes it will stall if I let off the gas. Once warm it runs really well. There is a new Cold Start Valve in the glove box, would replacing the old one with this new one solve this. I am totally unfamiliar with the cold start valve.

Thanks,

[ossiblue]

The cold start valve only engages when you turn the key to the start position, injecting fuel into the intake to initiate start-up. Your problem sounds more like a misadjusted Warm Up Regulator which enriches the mixture when the engine is cold, and leans it when the engine warms. Have you had your CIS system pressures checked? A too high cold control pressure would account for your situation. If you are getting an easy "first firing", then it's likely not the cold start valve.

Please post any additional information, such as back firing, popping, etc. You may also have vacuum leaks which are leaning the cold start mixture.

[RSWiser]

It is a bit hard to start in the beginning but then will only keep running after it is warm. Do I need to go to a Porsche specific shop to have the CIS pressure tested?

No backfiring no popping etc.

[ossiblue]

Originally Posted by RSWiser

It is a bit hard to start in the beginning but then will only keep running after it is warm. Do I need to go to a Porsche specific shop to have the CIS pressure tested?

No backfiring no popping etc.

Personally, I would go to a Porsche specific expert who know CIS inside-out. However, the CIS (Bosch K-jetronic) is also used on other cars like BMW and Audi so if you can find someone with expertise on the CIS, that would be fine. The actual testing is not difficult and any competent mechanic can perform the test, including yourself, but it does require information about ambient temperatures preformed during the test. Read a few posts on this board about CIS pressures (use the search button at the top of the page) and you will see it is not a big deal, but it is the first step to narrow down problems like yours and save you from chasing your tail by replacing expensive parts that may not be the problem.

Keep asking questions here, you're in good community hands.

Edit: I just read your other post about brake bleeders and realize the car is new to you. I would highly suggest that you find a good Porsche mechanic in your area--ask here, if necessary--and take your car to him and have your CIS given the once over to get it in full working order so you have a base line for performance. Make sure your ignition and valve adjustments are in order and get the CIS dialed in by an expert. Well worth the bit of expense, IMO.

[RSWiser]

Ossiblue,
thanks for the info. I have a client who specializes in European cars. Porsche and BMW specific. I will take it to him on Tuesday and have things checked out.

[Paulporsche]

Just to supplement what the others have said, make sure all ignition components are good. Have the mechanic check your fuel and warm and cold control pressures. He should also look for vacuum leaks. It is very common in these old cars that there are vacuum leaks in CIS components, the hoses, and around the intake runners and even the fuel injectors. The warmup regulator (WUR) is often out of spec or malfunctioning, resulting in a a too high control pressure and a too lean mix. He should set your CO to approx 3 to 3.5%, unless you have to pass an emissions test.

[boyt911sc]

Originally Posted by RSWiser

It is a bit hard to start in the beginning but then will only keep running after it is warm. Do I need to go to a Porsche specific shop to have the CIS pressure tested?

No backfiring no popping etc.

Rob,

You could check the fuel pressures (system, control, and residual) of you car without even running the engine. But you need a fuel injection pressure gauge kit to do it. CSV (cold start valve) could similarly be tested too. The pressure gauge kit costs about $60 from J.C. Whitney.

Things that primarily interets me when I do CIS troubleshooting are: fuel pressures and vacuum.

Tony

[T77911S]

take a look at the aux air regulator (AAR) on the right side of the motor. if it is stuck, it will make for a bad idle when cold. it should also have 12v on the connector.
the PO may have compensated for it by changing the idle when warm.