wow this thread makes my head hurt...Adam go here:
http://members.rennlist.com/jimwms/CIS/CIShome.html

Thermal valve:
Holds off vacuum from the warm-up regulator when engine is started cold ('77 - '79 engines). Power is applied to the thermal valve when engine is started, and approximately 30 seconds later, the valve opens. When the valve is open, vacuum to the WUR is then determined by the intake manifold. --The vacuum holdoff results in a mixture richening at warmup. The inner hose connects to the intake vacuum source and the outer hose to the WUR.

Safety switch on air flow sensor:
This switch prevents fuel pump from running when ignition key is on and the engine is not running.

Operation of the '76 and later relay:

The relay has two sets of contacts - Normally Open (NO) and Normally Closed (NC). In electrical lingo, "Normal" infers no power on the relay coil. On the basic Porsche round relay, pin 87 is NO, pin 87a is NC and pin 30 is the "arm" of the contact that switches between the two.

Relay Connections:
The fuel pump is connected to pin 30 of the relay socket. (Note that you can't jumper power to the fuel pump by jumpering +12 Volts to a fuse on the fuse panel. The fuse which protects the fuel pump is in the wiring that goes from the NC contact to the ignition switch). +12 Volts from the starter terminal of the ignition switch goes to the NO contact and +12 volts from the "Run" terminal goes to the "hot" end of the relay coil (pin 86) and to the NC contact. The "cold" end of the relay coil (pin 85) goes to the Safety Switch on the air flow sensor housing, and the other contact of the Safety Switch goes to ground. The switch is closed when the airflow sensor plate is at rest (engine not running).

Operational Sequence:
Ignition switch turned to "Run" (Not Start) - Relay energized. Relay contact pulled to the NO position.

Ignition switch turned to "Start" - Starter voltage goes to fuel pump through the NO contact. Fuel pump runs while engine is cranked.

Engine starts and ignition switch released from "Start" position - The Safety Switch opens as the air flow sensor plate rises off its stop. This de-energizes the relay coil, and the relay arm flips back to NC, sending voltage from the "Run" terminal of the ignition switch though the fuse and through the NC contact to the fuel pump. Engine is running, fuel pump is running.

Engine dies due to accident or other malfunction - Airflow sensor plate goes to its stop, closing the Safety Switch, and energizing the fuel pump relay (remember the ignition is still on). Relay pulls the contact back to the NO position. But since there is no voltage on this contact from the starter, fuel pump is disabled.

Control pressure regulator (also called Warm Up Regulator):
Drops control pressure when engine is cold, resulting in a richer mixture during warm up. . The term warm-up regulator is a bit of a misnomer in that this component actually regulates control pressure the entire time the engine is running. It changes the pressure during the warm-up period. Power is applied to bimetal strip in the regulator when fuel pump is on. As the internal resistor heats up the strip, the control pressure supplied to the fuel distributor increases, leaning the fuel mixture. On cars with vacuum control, the WUR enriches mixture under load determined by lower intake manifold vacuum. Some versions also modify pressure with altitude. Lambda sensor systems don't use the vacuum chamber because of this adjustment being automatically accomplished by the lambda system electronics box. '81 saw a change in the internal resistor configuration for the WUR. A second resistor was added to heat the bimetallic spring, controlled by a bimetallic switch. This allows the mixture to lean out more quickly after start-up,about 2 minutes compared to the former 3 minutes.

Good stuff, Ron.
Exactly as you describe. :)

Just came back from Seattle with my 915. JW applied his magic and did some surgery on it.
Winter project is to mate the "new" 915 to the SS 3.2 I built and swap it for my current 3.0. For the SS 3.2, you may remember that I use the CIS from a '78 on top of an '82 bottom with 98mm P/C's, 964-cams, SSI's.................
I plan to just run it briefly and wait for Spring to run it hard to seat the rings. I'll keep the 3.0 for a while but may sell it at some point.
Of course, no TTV on my set-up, just the correct WUR. :D
Did you keep the TTV on yours?

Re: Hope this helps
 

Dr. Gunter,
I spent an hour analyzing and reviewing the electrical diagram ('78SC-US model) regarding your information as stated above.

My observation is that the thermo-time switch (TTS) does not energize the cold start valve (CSV) or sends 12 volts power to it. Rather acts as a timer-switch device. Meaning that the bimetal- heater limits the duration of the valve operation (time) or on-off switch to ground the circuit (thermo).

The TTS and the CSV are connected in parralel thus get energized simultaneously by the yellow wire during start-up. My CIS experience is limited and would like to know more. Thanks.

Tony

Sounds good.
I think Porsche intended that the CSV would only activate during cold-start. That's why the TTS is mounted on the chain cover to sense the engine temp. When hot, the timer is out of the loop, I think.

the TTS is in series with the CSV. it acts like a light switch in your house except it is controlled by temp.

O.k. Back from Vaca. Turns out my home town of Danvers, MA blew up while I was gone. Chemical factory exploded. Equivalent of 2000 ton bomb. Key word so far being that I was "GONE" ( as in not around, not my fault). My house was 2.5 mles from ground zero. Just a little cracked plaster, no broken windows.
Here are the figures on the car
Cold Sys pressure 4.8 bar. Spec is 4.5 - 5.2 So OK there
Cold Control press is 1.2 bar. Spec is 1.6 - 2.9 So a little low
Hooked warm up connector back up to CPR
2.8 bar after 6 minutes. spec is 3.4 - 3.8 So very low
Checked supply voltage at connector and it's 11.4 volts. o.k.
So only other thing that could cause this condition other than bad CPR is restriction in return line. I imagine the only way to check this is to disconnect it at the tank and measure the flow. Looks like it should be about 750cc in 30 sec. Seems unlikely.Worth doing? Ever heard of that happening? Just replace CPR?
Ideas or input?
Thaks,
Adam

a restriction would cause a HIGH pressure.
connect a vacuum pump to the WUR and pull a vacuum with the car warm. pressure should go up. if u dont have one, go to advance or auto zone, it is worth the money.

Restriction in a return line, or blockage in the WUR would cause high pressure, I just went through that.

What are the abient(sp?) temps, but it seems you just need to pull the plug out of the WUR a bit due to cold AND warm being low.

From my (albeit limited) knowledge the plug only affects the cold control pressure. There is a thread about an adjustment screw that affects warm control pressure.

Carefully check/clean the screen in the line to the WUR. Any dirt?

Just replace CPR? Where do I get a CPR?
 

Adam is helping me with my CIS unfortunately he is home sick today. We spoke breifly on the phone and he mentioned I might want to price a CPR for my SC. I searched the parts section on Pelican and found no such thing. Is the CPR the same as the WUR? If not anyone know where I can buy a CPR?

Thanks to all who have offered us help and advice! I hope to be driving the car soon!

Andrew

Andrew,
CPR is Control Pressure Regulator which, I believe, is Bosch-speak for what many people call warm-up regulator of "WUR."

Good luck!

Yeah, and very pricy. You want to be sure that you need a WUR by checking the Control Pressure first.

Is someone just guessing here? :)

:-) No guessing....
 

Adam, told me not to buy it. He knows I am trigger happy to buy new parts. He just suggested I price and locate one just in case. He is down for the count with a cold. When he gets back to my car he will let me know if I need a WUR after he runs more tests.


Hopefully I won't! Does anyone know of the best place to buy one in case I do need a WUR?

Thanks again

Andrew

Is there such a thing as a CIS fuel tank?
 

My car has a custom center fill tank I bought from TRE. Could this be causing some of the problems I am having? Is there such a thing as a CIS fuel tank? The center fill I bought from TRE does have a return tube and seems to have all of the same connections the original factory tank had. Just wondering if this could be part of my problem.

Thanks

Andrew

Gunter,
Where is the screen located that you are suggesting I check?
Dweymer,
"but it seems you just need to pull the plug out of the WUR a bit due to cold AND warm being low."
What plug?
KFJ_SC,
A warm up adjustment screw? Where is this? Never heard of it.

My Bosch book was very quick to say to replace the WUR/CPR if the pressures were low and there was good fuel supply and voltage to the connector. Are there any other references that have more detail as to analyzing it in more detail cleaning it/adjustments. Is Bosch just trying to generate revenue or is it really not that repairable? I should probably look at some of the threads you guys have pointed out. Any one in particular that focuses on this issue past what we have discussed.

Gunter,others,
What is your recommened list of actions I should take on Sat to get a better diagnosis?

Thanks,
Adam

put a vacuum pump on the WUR. it should increase pressure with an increase in vacuum. that will also check that the diaphram is good. it should hold a vacuum.
my brother tried adjusting his WUR, finally just went and bought a new one and it fixed hard starting and overall running.

Got my WUR adjusted!!!
System pressure-4.75bar
Cold control-2.25
Warm control-2.9

Thanks ALL.

Now on to the idle & mixture

Adjusted?
What exactly did you do? :confused:

2.9?

This is the post I was referring to:

http://forums.pelicanparts.com/showthread.php?s=&threadid=178902&highlight=WUR+ad justment

Gunter,

The previous owners of my car were a creative bunch. When the WUR failed to warm up they knocked the plug out to increase warm pressure, then they adjusted the mixture to compensate. I knocked the plug back in so my cold control was within spec 2.25. Then I fixed the power supply to the relay, and Voila, warm pressure=2.9, which is in spec according to my factory manuals. Then I had to play with the mixture to get it back in reasonable condition. Now all I need is a CO tester to get it right on.

BTW: searching for more CIS info I found this Bosch CIS book online, is this one you were referring to?

http://www.phat-gti.com/downloads/boschtech-12d.pdf

Are you sure?????
 

I just checked the wiring diagram for the CSV and TTS. The wiring diagram says otherwise. Could someone knowledgeable in electrical wiring explain the discrepancies about T77911S's and my assumption. Learning new things everyday.....Thanks.

Tony

Excellent link, Donnie! Thanks!

Brian

boyt911sc,
the way the drawing shows it, the "heater" part of the TTS is in parallel with the "switch" portion of the TTS which is in series with the CSV. (did i just confuse the heck out of ya or what).
power is constant to the "heater" side. the "switch" portion applies a ground for the CSV when cold to allow it to operate. once hot, the ground is removed to turn off the CSV. if u are still uncertain about this, let me know what it is.

Cleaning WUR and takigng apart
 

I checked out a few more parts of the CIS system. I'm getting closer. Things like the Auxiliary air Reg are working fine, etc. I plan on checking the injectors for good spray too. They just pop out right? Only o-ring holding them in. Probably should have fresh orings to replace them when I pull them? Even though WUR pres numbers are good I wanted to check internal screen as Gunter suggested. Where exactly is it and do I have to remove WUR to do it?
Incase anybody wants to ponder symptoms more this is what they are.
----------
Starts fine when cranking (cold start valve is good). Stalls. Does this about three times then idles nicely. While cold if you push gas pedal it pops and then stalls. When warm everything runs great. I assume poping means that it is going lean when you hit pedal. So basically there is some fuel correction for the increased air flow that is not happening.
---------
Have looked over a few of the sites and threads that you guys suggested and didn't see an exact match for these symptoms. For the ones that were lose they just seem to list a bunch of parts to check. Not exactly specific to my case.
Looked over that WUR adjustment trick but since I have good warm conditions I don't want to do it yet. It also seems to me that it may just be a cover up for real problem.
Thanks,
Adam

Have you verified the timing?

Out of curriosity, unplug the wur electric and try it, see if it still does it with a warm engine, but cold wur.

Have you checked the airflow sensor plate to make sure it is not "gummed up".

The screen is on the inlet side of the wur, removal would be required, then remove the nipple for the fuel inlet. The screen is right there, flush with carb cleaner, or gas.

Injectors pop out, use a 15mm against the bung and a 12mm to pry against that.

Seems you may just be a little lean, have you set the mixture to the correct CO level while warm?

Re: Cleaning WUR and takigng apart
 

The WUR can stay mounted but, it's easier to work on when taken out.
If you want to disconnect the electric plug, watch that small wire-clip.
Carefully remove the line on top of the WUR. (For the line with the cap-nut counter-hold the fitting with another wrench).
Check the small screen for debris.

It's easier to pull out the injectors if you spray a little WD-40 on the O-rings first; pry straight up with the help of a wrench fitting under the cap-nut.
You can do them single, or you can use 6 clear glass bottles and observe them one by one.
Ignition on, lift the air flow sensor plate.
Have a fire extinguisher handy!

Should I have new injector orings ready for replacment? Do you need to remove the injector seat ( using special tool) to change o-rings?
Adam

Not a bad idea to have some (so why not have 6) new O rings in case some of them look cracked.

I like to have at least one of the phenolic inserts and its own, different, O ring, on hand, too. Just in case one of these comes out with the injector and gets damaged. They are held in by staking the aluminum around the hole - you can see how that is done before you start.

Walt

Thanks Walt. The book also says to remove the line from the injector. The line is pretty flexable. Is it really necessary, i.e. are you likely to damage line?

adam:
To test the injectors, or to replace the O-rings. you don't need to remove the line.
The old O-rings give you enough play to pull the injectors straight out after you spray some WD-40 on the O-rings.
After you finish testing, replace the old O-rings with new ones, then smear some Vaseline on the new O-rings and pop the injectors back in.
However, you can remove all injectors and soak them for 1-2 days in a small can of injector cleaner to clean the small screen inside the injectors, then blow out with air.
The inserts are usually not damaged, you'll have to see.
Replacing the inserts is a different kettle of fish; much more work.
To prevent any debris from falling into the heads, and to make it easier to work, you need to remove the intake runners meaning:
Loosen the clamps around the rubber boots on the runners, remove the 2 nuts on the intake flanges, remove each intake runner, check the condition of the gasket between runner and head; these gaskets are one place where vacuum leaks occur.
If you plan on replacing the inserts, you might as well get a set of new gaskets. If the inserts are good, check the torque of the nuts on the studs for the runners; you'll need a 13?mm swivel-head socket with a large extension for that. Check the condition of the rubber boots on the runners.

Gunter is a far more meticulous mechanic than I.

I would never remove the runners just to pull injectors. That is a bear of a job with the engine in the car, some nuts are hard to get to, and some of the hose clamps probably were installed with the engine on a rotating stand and are at orientations nearly impossible to get a screw driver into their slot.

But on rereading his post I see that he is referring to replacing the inserts. That is, indeed, a different kettle of fish. I am trying to remember if I have ever removed one that didn't come out on its own by accident. I don't think so.

I recently replaced my O rings because I had noticed some looked cracked. Turns out they weren't that bad, but I did it anyway. While, thankfully, the plastic insulator pieces stayed put, I have had some come out on me. Hence my desire to have a spare or two on hand, lest a short job end up with the car laid up for several days awaiting a part. Sometimes the insulators that decide to come out can be reinstalled, but sometimes they break along the way.

My first 911 engine was a '77 2.7. Those had a plastic injector line, quite flexible. So I was hesitant about this with my 3.0 with the nice steel lines. But it is no problem to flex them to the side after loosening the nut holding them to the injector. Or even poping them out far enough that the seal is above its notch before removing the line.

Walt

I took apart the WUR last night. Lower diaphram is fine ( holding suction). Upper chamber was not holding vacuum very well. Is there anywhere I can get the o-ring that seals the two case halfs?
Other note: Heating element green insulation was cracked with big chunks falling off. I doubt that makes any difference especially since it seems to be behaving normally.
Adam,

x2. I also took my WUR apart last night and noticed a small section of the seal that is slightly corroded which would obviously cause a leak. If the o-ring is difficult/impossible to get, would something else suffice?

i tried to get you to check the vacuum 2 pages ago. the vacuum from the engine is connected to the top chamber. with the engine running, it should bring the pressure into the 3.4-3.8 range. if your top chamber is leaking, that is why your pressure is low. i will have to look at my old WUR again, but you could be leaking between the middle section and the diaphragm. creating air leaks is why i dont encourage anyone to open their WUR, unless they know it is the problem. the 1.2 will also be higher with vacuum, unless the TTV is not working. you may try silicon on the seal if u cant find a new one.
have u checked the TTV to make sure it is not leaking, if u have one?

i hope these numbers will help
my specs on a 3 yr old WUR:
cold no vac- .8bar
cold with vac- 1.8bar
warm with no vac- 2.9bar
warm with vac- 3.6bar

I did check the vac before busting it open and that is where I discovered it leaked. I guess I will have to grab an o-ring kit and make one for it. I had another question. The vac line that goes to the bottom of the diaphram. I would assume that this is just referencing atmosphere press. The line goes to a small flat round device that has a second hose coming out of it and an electrical connector. Haven't looked it up yet or what it goes too. Anybody have info on it

Yes, per this image, #9 is atmosphere - slightly different in the 78, but the principle is the same.

How are you going to make one with an O-Ring kit? won't you have a gap?

http://forums.pelicanparts.com/uploa...1093387343.gif

Oring kits are spools of O-ring material (different diameters) with a special glue that can be used to make a closed ring. They work very well.

So what is that little puck thing with the electronic plug that the atmosphere reference (#9) goes too?