1980 911sc potential CIS lambda issues during engine drop

[Parr]

Hello Everyone,

After owning my 911sc for close to ten years, I've finally begun my first engine drop to fix all the oil leaks I can find and give everything a good cleaning.

Things have gone smoothly, and I'm almost ready to put the engine and transmission back in, but I have some questions about a few things I'm seeing.

I'm mostly concerned about some of the CIS components.

I'm having trouble finding out if two components are missing something, haven been altered, or are correct. Please see below.

For the metal box in pic 1, the wires coming out the top are cut. Where should they be connnected, and why would someone cut them?



For the part in pic 2, should there be a vacuum hose connected here?



Thank you!

[pmax]

The saucer on the top is the wrong unit. You need the doodad without the nipple called the AAV.

https://www.pelicanparts.com/More_Info/911110273X.htm

$1000 !
Used would be cheaper

[boyt911sc]

Parr,

Picture #1:
An external voltage regulator was used in ‘’78~’79 SC and was later replaced by an integrated VR in the alternator.

Picture #2:
You have the wrong CIS part. That is a decel valve and exactly the same as the one with the vacuum hose in the picture. It should be an AAV (auxiliary air valve).

Compare this picture to yours:


These are the AAV that you need to install.


PM me your address and I will have one shipped to you.

Tony

[Parr]

Thank you both for responding so quickly.

Tony, lets do it!

Could the wrong part I have installed be throwing off air/fuel mixture?

On the voltage regulator, so I have nothing to worry about there?

[boyt911sc]

Originally Posted by Parr

Thank you both for responding so quickly.

Tony, my address is 2625 leroy lane, West bloomfield MI 48324. Thank you!

Could the wrong part I have installed be throwing off air/fuel mixture?

On the voltage regulator, so I have nothing to worry about there?

Parr,

An AAV is normally open ((NO) and would close when vacuum is applied. While the DV (decel valve) is normally closed (NC) and would open when vacuum is applied. They operate and function completely different from each other.

So when you inadvertently installed a DV in place of an AAV you will have some minor problem with the operation of your CIS. You might not noticed it, but the cold start would slightly be affected and worse, if the DV is leaking, you will have unmetered air going into the system.

Best thing to do is install a good working AAV in place of the errant DV.

Verify and confirm that you have the upgraded alternator version with integrated VR.
Keep us posted.

Tony

[Parr]

Tony,

I've been trying to reach you to do this swap. I left you a few messages.

Please give me a call when you can, and thank you again for the assist.

[boyt911sc]

Michael,

The AAV is on its way now and should be there in 2 days maybe 3. It was tested before packing. See picture below:



Do not forget to test the decel valve, you have 2 of them. And we’ll do the swap later. Thanks.

Tony

[pmax]

Parr,

Have you done a vacuum leak test ? If not, make sure you do.