73 S - MFI cold start solenoid question...

[mac73s]

When I took delivery of my mostly apart 73 S, the previous owner mentioned having run a wire from a rocker switch below the speedo (one lead connected to the black power lead on the back of the clock and the other terminal wire routed through the tunnel to the solenoid) to aid starting the car in cold weather. The engine, MFI pump, throttle bodies and stacks have all been rebuilt, and I would like to gather thoughts on whether or not this added feature of being able to manually 'fire' the solenoid is something I should keep?

[RSTarga]

I've never needed it.

[majordad]

I have needed it and I find it helps hot starting.

[Flieger]

I had Tony and Marco at TLG convert my cold start solenoid (the one that squirts the raw fuel down the stacks) to manual operation only. I did this because if I shut the car off in hot weather and let it sit for just the right amount of time it would take forever to start since the thermo-time switch thinks the car is still warm but it really needs enrichment to get the engine to "catch". I much prefer the manual system. It starts easier cold since I can give it several squirts to keep the car from dying out (my thermostat is blocked off, set in the fully warm position because I have headers and so no way to send heat to a thermostat- this makes cold starts harder).

[edmayo]

For stock applications I don't find it necessary,,,,,,if the thermoswitch, relay and grounds are correct, and in Texas you can bet we give hot starts a real test. You just have to learn how much throttle to give it, each car seems to have it's own mannerisms. That's what separates us from the robot cars,,,,with these cars you must be involved!

[Flieger]

For stock applications I don't find it necessary,,,,,,if the thermoswitch, relay and grounds are correct, and in Texas you can bet we give hot starts a real test. You just have to learn how much throttle to give it, each car seems to have it's own mannerisms. That's what separates us from the robot cars,,,,with these cars you must be involved!

I think my situation was not helped by my missing thermostat. It would always take 3 starts to get the car to keep running from cold, and lots and lots of cranking warm. However I found I had some dirty/bad injectors so I never really got to see which was the culprit, as the MFI was refurbished at the same time the manual switch went in.

[bliebler]

I don't think the cold start valve will help your situation as your car starts but will not keep running. The thermostat keeps the car running. My cold start valve works properly and one day I disconnected the hose at the thermostat and ran a really hot hair dryer into the thermostat to lean it out. The car started but did not keep running. At times I have disconnected my cold start valve and it may crank a little more but once it starts it keeps running.

[Macroni]

I opt for a properly running cold start as designed by Porsche.... but as Ed stated you need to know how to start the car in various states of temperature.....

[mac73s]

Thank you all for sharing your thoughts...another reminder of what a great resource (and people) populate this forum!

[cmcfaul]

I bypassed the thermal time switch and it works perfectly, Starts in two seconds or less every time, hot or cold. I did mine the way ther Thermal Time Switch is supposed to work. When the starter is engaged and the switch is ON, it squirts fuel until the starter is turned off. When hot, simply turn the switch off as the extra fuel is not needed.

Very simple and starts right up every time.

Mounted the switch on the tunnel access door so not noticable.

Chris

73 911 E