Pelican Parts Forums - Another cold start challenge

Pelican Parts Forums (http://forums.pelicanparts.com/)

- Porsche 911 Technical Forum (http://forums.pelicanparts.com/porsche-911-technical-forum/)

- - Another cold start challenge (http://forums.pelicanparts.com/porsche-911-technical-forum/700761-another-cold-start-challenge.html)

You really need to know your fuel pressures to do any diagnostics.

For your WUR cleaning go to page 13 of this thread:
http://forums.pelicanparts.com/porsche-911-technical-forum/664950-1976-911s-garage-find-road-13.html

On a side note, my car started like crap until I fixed a small vacuum leak from a mildly cracked airbox that I could only detect with a bubble test (replaced it) and replaced my plugs, wires, cap rotor etc....

TTS operating temperature......

Quote:

Originally Posted by Bob Kontak (Post 6949163)

CIS Primer says 113F. Sitting in the sun should have no problem exceeding that where palm trees can grow. Phonix - In the shade will kill it.

Bob,

You were correct in posting the opening temperature of the TTS @ 113°F/45°C. The source where you got the data is very reliable and thanks to Jim W. You meant Phoenix, AZ?

Tony

Quote:

Originally Posted by RarlyL8 (Post 6949433)

113°F must be a typo, that would imply the CSV is active when the engine is not fully cooled down. The CSV is on a thermo time switch which remains open until <15°C. This can be varified in the Porsche shop manual. Years ago when I moved from IL to AL the CSV was disabled from my engine as it is not needed in this climate.

One important thing we haven't covered is history. When did this condition begin, what symptoms occured as it progressed, and was anything done to compensate for the symptoms. If anything has been done to compensate it must be un-done to help find/fix the root cause or you'll be chasing your tail.

Brian,

The TTS remains closed or grounded until it reaches 113°F/45°C. Above this temperature (engine temperature), the CSV is disabled due to the open circuit provided by the TTS.

Before getting hold of the manual/s, my tests some years ago showed @115°F using my wife's kitchen temperature probe and cooking pot with water. Pretty good results for DIYer's. What made you think it was a typo? Have you checked the shop manual recently?

Tony

The Porsche factory manuals are open on my bench every day; a main resource for the CIS work I do. Jim Williams, author of the CIS primer, lives just over the hill from me and we consult together often. We were both surprised when we met at a PCA meeting a few years back and learned of our mutual interest in these old fuel systems. I'll ask Jim to check and see if we are talking about the same part. The thermo-time switch I am refering to controls the cold start valve and is screwed into the left hand chain housing. According to the manual the switch is grounded when the engine is cold (<15°C). Upon starter engagment the switch will warm and lift off the ground thus closing the CSV. On my personal car the CSV was eleminated as it doesn't typically get cold enough in AL for it to be of use. Removal did not change how the engine started cold.
A go-no go test of the CSV would require the unit be kept at a static temperature for enough time to allow heat soak of the bimetalic strip.

Everything OK except your number........

Quote:

Originally Posted by RarlyL8 (Post 6976947)

The Porsche factory manuals are open on my bench every day; a main resource for the CIS work I do. Jim Williams, author of the CIS primer, lives just over the hill from me and we consult together often. We were both surprised when we met at a PCA meeting a few years back and learned of our mutual interest in these old fuel systems. I'll ask Jim to check and see if we are talking about the same part. The thermo-time switch I am refering to controls the cold start valve and is screwed into the left hand chain housing. According to the manual the switch is grounded when the engine is cold (<15°C). Upon starter engagment the switch will warm and lift off the ground thus closing the CSV. On my personal car the CSV was eleminated as it doesn't typically get cold enough in AL for it to be of use. Removal did not change how the engine started cold.
A go-no go test of the CSV would require the unit be kept at a static temperature for enough time to allow heat soak of the bimetalic strip.

Brian,

Just take a look at the TTS. Stamped on it is the switching temperature (+45°C). Like most temperature switches, the temp. setting is stamped on the switch's body (45°C is translated as 113°F). I happen to have a few TTS lying around that I used in my experiments and testing years ago. BTW, TTS operates between 5-7 seconds before switching off.

In Summary: TTS is closed below 45°C/113°F allowing the CSV to inject fuel during cold start-up and open (CSV disable) above this temperature.

http://forums.pelicanparts.com/uploa...1347682305.jpg

Tony

The TTS operates a few seconds before it shuts off because that is how long it takes for the electricity to heat up the bimetalic strip to (45°C in your case) and lift off ground.

Your picture brings up a troubleshooting point; there are different versions of TTS and our cars are 20+ years old. If the TTS failed in the past it could be replaced by a different switch.

Nomatter which TTS your engine uses it is a very simple test to see if the problem you are having may be related to the CSI - disable it.