1977 911 CIS Cold Start Issue Question

[Porschahh]

My 1977 911S has vacuum routed like it was in 1976 - without a Thermo Valve in line with vac to the WUR. Give the Thermo Valve was removed again a few years later (on model year 77, 78 and 79), I can think it was a band-aid for cold start issues and it didn't work.

I am working thru a cold start issue that is resolved by just resting a foot on the gas pedal. The car will not start without this action. After it starts, it will surge and die if I remove my foot. Otherwise, I hold it there for a few minutes at 1200 rpm to let it warm up and it runs fine afterward. Because of this, I am suspect of the AAR and possibly the CSV.

For those CIS wizards, does this make sense?

PS - car has a digital WUR that is programmed to replicate the 033 WUR.

[boyt911sc]

Originally Posted by Porschahh

My 1977 911S has vacuum routed like it was in 1976 - without a Thermo Valve in line with vac to the WUR. Give the Thermo Valve was removed again a few years later (on model year 77, 78 and 79), I can think it was a band-aid for cold start issues and it didn't work.

I am working thru a cold start issue that is resolved by just resting a foot on the gas pedal. The car will not start without this action. After it starts, it will surge and die if I remove my foot. Otherwise, I hold it there for a few minutes at 1200 rpm to let it warm up and it runs fine afterward. Because of this, I am suspect of the AAR and possibly the CSV.

For those CIS wizards, does this make sense?

PS - car has a digital WUR that is programmed to replicate the 033 WUR.

Porschahh,

If you have to use your gas pedal to start your CIS engine, there is inherently wrong with your CIS. Fuel injection system engines DO NOT NEED assistance from your gas pedal to make it start. I use an engine test stand to troubleshoot CIS motors by just turning the ignition switch to START. If the motor fails to start, something is not RIGHT. Start diagnosing for the culprit/s.

You need to know your fuel pressures (CCP, WCP, SP & RP). Ignition coil, spark plugs, and timing should be good too. And don’t forget to look for unmetered air going into the system. Good luck.

Tony

[Porschahh]

Already been down that path. Leaking fuel lines corrected, all pressures in spec. Injectors tested and in spec. Smoke tested vac system and all good. Replaced CDI box that failed with MSD. Pertronix electronic points. New coil.