Cold start issue

[mordecaibrown]

I have a 1977 Porche 911s engine totally rebuilt 3K miles ago. Took it to the Porsche shop and they replace faulty Vacuum element and adjusted ignition timing and fuel mixture. This fixed the cold start issue! They also recommend as some point new spark wires and coil as there some some miss fire under load. Had a friend / mechanic put wires, cap, plugs and rotor on, plus time the car, and runs like new, except the cold start issue is back. Any suggestions?

Thanks,

Sam

[Paulporsche]

Some questions first:

Where are you? How cold are we talking here?
Did your friend change the timing from the previous?
Did anyone check the fuel and control pressures?
What vacuum element was replaced?
What is the cold start issue? Can you give us some specifics?

[mordecaibrown]

Paul: In Chicago, about 25 degrees today. I am not sure on the timing I will as him? It said on the receipt that the Porsche shop adjust igintion timing and fuel mixture. Did not say what vacuums element was changed on the receipt. When I first got the car a few months ago. When turning it on I had to hold the gas peddle down about a minute until the car ran on its own. After I got the car back from the Porsche shop it did not have to do that, Just a couple cranks and she started up and idle on is own, but had a very bad miss fire under execration. After my mechanic friend replace the spark wires, plugs, rotor cap and rotor, car ran great, but again i have to hold the gas down about a minute before it will idle on is own.

Thanks,

Sam

[obscene]

new plugs might be gapped too wide.

[Paulporsche]

A CIS equipped car, like yours, shouldn't need, or even have, the gas applied while starting. Doing this doesn't have any effect at all on starting.

Assuming the new ignition components are all working correctly, you should check the operation of your warmup regulator (WUR) to see if your fuel and control pressures are within spec.

You should also check to see if you have any vacuum leaks, which are very common in cars as old as yours.

You should also verify that your thermotime switch and cold start valve are operating correctly.

And lastly, to what CO% was your mixture set by the first mechanic?

No guarantees, but it seems that the most common reasons for cold start problems, after ignition faults, are a too high Cold Control Pressure (WUR) and vac leaks.

[mordecaibrown]

Thanks Paul I have those things checked out!!!

Sam