CIS newbie questions stuff - not connected????

[Chris Morse]

I am putting things back together after the great thermostat blowout tragedy.

10 years (and 10K miles) before my dad passed away, he had a $12k rebuild on the engine. The car passed to me and i put a carrera cooler and thermostat on the pristine 74 911 and shortly thereafter, the thermostat popped up out of the block, ("somebody" overtightened the 6mm thermostat bolts) and hosed everything with 3 gallons of 20-50 synthetic. Got it shut off before it rattled the motor.

We stripped it down to the long block and cleaned everything. I started replacing old gaskets, seals,hoses and making thngs right, clutch, rebuilt alt,paint fan, ect.

I have to back up to my initial receipt of the car. I took the car to my dad's long time mechanic for a checkout. I wanted to make sure i could get it 450 miles home. I kenw the car always ran hot and asked them to check the timing and fuel injection, so i didn't toast it trying to get it home.

They reset the points, timing and disconnected the fuel hoses going and coming from the device that looks like a throttle positon sensor, (see pic). I was told that there was a vacuum leak, the part was for emission part throttle leaning and that i didn't need it, since the car was exempt from CA emissions. The car got 16 mpg on the easy drive home.

Were those guys blowing smoke up my azz??? do i need to hook this device back up???

When i got the engine out, i found that the one inch diameter pipe angled down (7 oclock), with no hose attached. This is the pipe that seems to come out of the cold start valve. I have searched a lot of sources and cannot find where this fitting is supposed to end up going. This is the "nipple" that is just above the crank case breather.

I am trying to replace all of the old hoses and get things right but am unable to find a hose diagram.

help,
chris

[snbush67]

CIS Primer for the Porsche 911

[HarryD]

That is your Cold Start Injector. It is used to richen the mixture when you go to start your car. Without it, it is very hard to get your car started when it is cold.

It appears to be missing several parts and connections. This page in the Pelican PArts Catalog shows the parts: Porsche 911 & Turbo CIS Fuel Injection - Page 10

One thing missing is a line from your fuel distribuor to this part.

[kodioneill]

That red piece does not have a passage through it. It's used as a spacer.

[Chris Morse]

Thanks, Snbush67,Harry and Kodioniell,

I have looked at the same diagrams and parts pages but i have been unable to find where this $544 dollar hose goes.

I've got a biece of bulk hose coming Monday to go from the engine breather to the dry sump tank and from the air cleaner housing to the tank.

The clip, boot and wiring connector to the cold start valve is being repaired and heat shrunk and is disconnected at the moment.

Two questions; where does that $544 hose go? The Page 10 at Pelican shows the hose from the hose hooked to the red spacer and says it goes to the "auxiliary air regulator" but page 11 shows the regulators for models 1976 on. Is it likely that someone installed a later model part. It sure looks like it needs a hose, at least to the air cleaner or it should be plugged off???

In my hurry to become cis savy, i forgot to post the picture of the disconnected "throttle position controll regulator" which

"Early CIS only ('73 - '75) Operated by a cam driven off the throttle shaft. Enriches the mixture at full throttle and at idle by decreasing the control pressure.

Failure mode: Leaking diaphragm keeps fuel mixture too rich at part throttle.

I was toldby my dad's shop that "this leaned out the mixture for emission reasons and didn't need it to be connected"

? should i reconnect this?

Mired in ignorance and BS,
chris

[ossiblue]

The red piece is in fact from a later CIS. The nipple connects to a hose that goes to the AAR, as mentioned in your post. Your 74 does not have that device so I suspect someone added the part as a spacer--the cold start valve itself looks to be the correct year as later versions that go with the red piece use a banjo fitting for the fuel connection. I would simply plug the nipple opening as there is no need for a hose connection on your car--you have the hand throttle/micro switch set up for cold start. With the nipple open, you likely do have a vacuum leak.

[Walter_Middie]

I don't have any pictures of mine right now, but I think my 75 also has that same red spacer on the cold start valve. It has what looks like a connection for a hose, but it goes nowhere, and there is NOT a hose connected to it. It's just left "open" (I think it is not open, I think it is plugged).

As kodioneill says:

That red piece does not have a passage through it. It's used as a spacer.

[ossiblue]

I believe both Rex and Kodioneill that the hose connection is not open. However, for peace of mind, you might want to simply probe with a small wire to see if it is blocked. Regardless, nothing needs to be connected to it and it should be sealed from air intake.

[Walter_Middie]

The confusion may come from the parts catalog that incorrectly shows the same picture for all years of the CSV. This incorrect picture shows a hose connected to the CSV mount and is just repeated for all years regardless of accuracy.

Porsche 911 & Turbo CIS Fuel Injection - Page 10

However, the actual hose itself is labeled as:

Parts catalog number 911-110-277-01-OEM

Hose, from cold start mount to auxiliary air valve, 911 (1978-83)
$544.25

So the hose is for early SC's with an auxiliary air valve - something our earlier mid-year cars do not have. We use the hand throttle between the seats for increasing the idle RPM when cold.

[kodioneill]

My 74 2.7 has the red block spacer. I think it was made for future cis systems but implemented in 74. You are missing a hose that will cause a serious air leak though. look at the upper right corner of photo. That brass bell shaped item is the vacuum limiter, both the large hoses connect to the throttle body in the rear the small hose is connected to manifold vacuum.

[kodioneill]

This is the valve I'm talking about.

[Chris Morse]

Thanks, Ossie, Walter and Kodi,

Well that is a big relief, not having to buy that $544 hose ;-0 I will probe and cap the hose barb.

What do you guys think about the mechanic leaving the throttle regulator disconnected?? I am inclined to hook everything back up as it was designed.

How can i test the throttle regulator??

Thanks,
chris

[Chris Morse]

Originally Posted by Chris Morse

Thanks, Ossie, Walter and Kodi,

Well that is a big relief, not having to buy that $544 hose ;-0 I will probe and cap the hose barb.

What do you guys think about the mechanic leaving the throttle regulator disconnected?? I am inclined to hook everything back up as it was designed.

How can i test the throttle regulator??

Thanks,
chris

One more question: Can i test the throttle pressure controll off of the car. it would be a lot easier.

thanks,
chris

[ossiblue]

The throttle regulator was replaced by changes in the wur and (other CIS components?) found in 75 and later CIS that allowed for enrichment during wide open throttle. The 73/74 wur is different (and NLA) unique to those two years and required the regulator. I would tend to hook everything back up as intended, though I don't have experience with the throttle regulator--my 73 is running a 76 2.7L.

[T77911S]

Originally Posted by kodioneill

My 74 2.7 has the red block spacer. I think it was made for future cis systems but implemented in 74. You are missing a hose that will cause a serious air leak though. look at the upper right corner of photo. That brass bell shaped item is the vacuum limiter, both the large hoses connect to the throttle body in the rear the small hose is connected to manifold vacuum.

are you talking about the decel valve?
there hose is there, it is just not connected to the side port of the DV. cant tell if it is plugged or just lose.

[Chris Morse]

Originally Posted by ossiblue

The throttle regulator was replaced by changes in the wur and (other CIS components?) found in 75 and later CIS that allowed for enrichment during wide open throttle. The 73/74 wur is different (and NLA) unique to those two years and required the regulator. I would tend to hook everything back up as intended, though I don't have experience with the throttle regulator--my 73 is running a 76 2.7L.

Thanks Ozzi,

I am in the porcess of trying to get everything back to stock, replacing all vacum, fuel and evap hoses. I will hook it up and proceed with having a bung welded into the tailpipe so i can install an LM1 o2 sensor for verification purposes.

thanks,
chris

[Chris Morse]

Originally Posted by T77911S

are you talking about the decel valve?
there hose is there, it is just not connected to the side port of the DV. cant tell if it is plugged or just lose.

Hi T7,

Yes you have caught me with my decel valve un-hosed. I just today got the proper fabric covered hose to recitify this malady and both breather hoses as well! This stuff is not easily sourced locally - thank you pelican for sending up the right stuff.

FWIW, i am replacing all hoses, including the brittle evap hose that runs to the tunnel. I need to have a sound starting point for my stewardship, that sounds a bit stuffy, but i want to do it right.

Thanks guys for all of the help,
chris

[handdrawnsquare]

so what is the verdict for that red fitting/spacer at the cold start valve? it is not blocked in the interior of the air box. actually there is a smaller metal manifold in the interior of the airbox from the coldstart valve to the centers of the 6 seperate intake outlets of the airbox.

if i block the connection there is no way that the cold start valve will function very well because the atomized gas from the injector would condense on the cold metal walls of that smaller manifold system before the atomized gas would have a chance to enter the intake runners.

so for me it is obvious that it needs air intake at the coldstart valve. i have a 1975 911s and it is not connected.

the idea of un-metered and more importantly un filtered air being allowed into the engine also seems very strange to me.

so in therory it is a functioning air leak into the system. i'm thinking of wanting to connect it someware it can be filtered and metered.

the oil vent tube at the left side of the airbox seems to be a nice place to make a t-joint.

i do have someother disturbing information and that is that the porsche dealership here in france told me to plug it.

either way, if i plug it or move it to a filtered metered location i will need to do an idle and mixture adjustment.

if i plug it the mixture will be rich and if i move the opening to before the meter plate it will affect the volume of air passing the air flow sensor. this will increase idle very slightly maybe the idle screw can compensate for the small increase in air flow.

i am hoping for a definitive answer to if i should plug it or not and what is the part number of the plug?

maybe i just think too much

thanks

[Walter_Middie]

On my 1975 it is not open. Are you sure yours is open? Have you removed it and looked at it closely? I don't think your car would run with that large of an air leak. It must be closed.

[handdrawnsquare]

thanks for the info about you car's spacer.

are you sure that yours is closed? i hooked a hose up to mine so i could plug it easily and when i do the car runs like crap. i have the feeling that the motor is running heavy or too rich. i'm sure that being open is affecting the mixture, idle etc.

I can see the spacer being plugged if there wasn't that mini manifold for it. maybe the airbox is from a later year?

Anybody know about airbox changes over the cis years?

I have a spare 1975 cis system that i can easily inspect and on that system it is open too.

I am waiting for a new alternator for the car and when it gets mobile again i will take the one off my car. it's a pain in the ass back there but a piece of mirror helps

i used to have porsche pet 5 and it had the 1975 model part numbers but since i moved i can't seem to find the disk. my current katalog is for a '77.

any body have a copy of pet 5 floating around? i would really like to find the part number for the proper piece.

thanks guys

robert