Line from Mixture control boot to Intake Manifold - SC engine

86 911 · 86 911's Garage

I went down to a local Porsche repair shop a couple of days ago and asked a mechanic where the vacuum line from the distributor plugs into. He showed me, and it was on the air flow sensor. I took my car home to plug in the distributor vacuum line and found that there was already a line on the air flow sensor. That line connected from the air flow sensor to the intake runner/manifold. I then disconnected that line and put the line from the distributor on. I started the car up, and it started fine. Does anyone else have a line on their SC (1978 or 1979) that goes from the air flow sensor to the intake runner? I have no clue what that line is and feel unsure about leaving it disconnected in favor of connecting the distributor vacuum line.

ianc · 04-05-2006, 08:52 PM

Quote:

mixture control boot

Look around until you find what this part is really called, because I have no idea what you're talking about...

ianc

86 911 · 86 911's Garage

Sorry, the proper term is the air flow sensor. Here is the line I disconnected in favor of the distributor vacuum line:

It's the hose with the black arrow pointing to it and not the red colored hose.

Also, my air flow sensor has only one nipple for the 2 hoses, not two nipples as shown in the photo

. The diagram should be for a '78-'83, so I'm not sure why mine only has one nipple.

ianc · 04-05-2006, 10:28 PM

What year is your car\engine? Your name and your sig seem to be at odds, and your sig doesn't say what year.

Does the biscuit on your distributor have one vacuum line or two?

ianc

86 911 · 86 911's Garage

The engine is a 1978 911 SC and the car body is a 1976. The biscuit on the distributor is only made for one vacuum line. There is only one nipple on the air flow sensor as well, although there is already some line going from there to an intake runner.

Jim Williams · 04-06-2006, 04:04 AM

Matt,

Not to belabor the point about terminology, but what you have shown the diagram of is called the throttle body, not the airflow sensor. If you have a reference that calls it an airflow sensor, then it is wrong. You can look up the proper terminology for the CIS compnents here:

http://members.rennlist.com/jimwms/CIS/CIShome.html

Also, the intake runners are the cast aluminum tubes that connect the intake manifold to each individual intake port on the heads. They have no provision for any connection except at each end.

No intent here to give you a hard time here, but it would help others help you if you use the commonly accepted names for the components.

86 911 · 86 911's Garage

Thanks Jim. I'll try to use the proper terminology from now on. The line that goes to the bottom of the intake runner from the throttle body is a small rubber hose and it doesn't look like it affects the car much if I disconnect it.

86 911 · 86 911's Garage

Here are some photos of the line I am willing to disconnect in favor of the distributor vacuum line:
Connects to:

Goes to (it's the line in the back right with the white "collar"):

What is this line for? Is it safe to disconnect it?

brendon · brendon's Garage

That is th vacuum line for your control pressure regulator (sometimes called the Warm-Up Regulator, or WUR). Some regulators have this, some don't. My '80 SC engine is not supposed to have a vacuum controlled WUR, yet there is one in there; but the vacuum line is not connected.

I am still sorting out some driveability issues of my own, so whether or not this "needs" to be connected on your application I couldn't say for certain.

86 911 · 86 911's Garage

Woohoo! I passed emissions. Thanks Brendon. I will just leave that line where it is. I just needed to plug in the distributor vacuum line to pass smog, but instead I ran the line in back of my engine and faked it, but made it look functional. Anyway, I passed emissions, so now I'm happy

.

Jim Williams · 04-06-2006, 04:05 PM

Matt,

The connection to your throttle body in the first photo you posted is the atmospheric connection to the WUR. This is not a vacuum connection, but rather just a convenient place to connect the end of the hose. It is only an atmospheric vent for the WUR. The vacuum connection for the 1978 year of CIS is the one at the bottom of the WUR.

When you say a hose is connected to the "intake runner", I am not following this. The intake runners don't have a vacuum connection here, unless someone has modified one. There should however be a vacuum line on the bottom section of the WUR. This connection would be just out of sight at the bottom of your second photo. Does your WUR have one of these connections? Also, can you read the Bosch number on The WUR?

If your WUR has the bottom connection, follow where it goes, and post your findings.

If you connect the distributor vacuum line to the top connection on the throttle body, you won't get a vacuum here.

Here are the vacuum connections for the '78 911 CIS:

http://members.rennlist.com/jimwms/CIS/vaclines.html

Hope this helps,

86 911 · 86 911's Garage

Thank you for the info Jim. The vacuum hose which I mentioned earlier actually does go to the WUR, and not the intake runner. Yes, there is another vacuum line at the bottom of the WUR as you mentioned. The part number on the WUR is: 911-606-105-09-M14