Replacing Electronic Change-over Valve

[78F350]

I was getting a CEL with codes for P0140 and p1411. Also the Blower for the Secondary Air Injection System was loud, like a vacuum cleaner with a blocked suction. First I replaced the blower, but that didn't change anything. Next after some research and double checking the vacuum lines I tried replacing the Electric Change-over Valve. I'm running fine with no CEL now and the blower is sounding normal.

Best access is by removing the alternator I kept it wired, but pulled it forward out of the way.
1. Remove the panel behind the seats.
2. Remove the serpentine belt.
3. the Alternator is held in with 2 bolts. The one on the right runs through an idler pulley.
4. With the alternator removed you can access most of the SAI system. The change-over valve is circled:


The valve clips onto a bracket at the bottom. There are two vacuum lines and one electrical connection.
The hardest part was getting my big hands into position to connect the vacuum lines.

There are a few more parts of the system, that can fail, or the passages in the SAI can be clogged, but this seems to have fixed it for me. I'd say #1 check the vacuum line for a leak before replacing other parts. While you are in there it's a good idea to replace all of the vacuum lines anyway if they are over 10 years old.

Here's the basic diagram, but layout varies by year and transmission:

[flaps10]

So based on your photo the change over valve is number 18 in the diagram?

[78F350]

Originally Posted by flaps10

So based on your photo the change over valve is number 18 in the diagram?

Yes. Here is the same diagram, with the rest of the key appended.




Clipped from this:
http://www.porsche.com/all/media/pdf/originalparts/usa/986_USA_KATALOG.pdf

edit: well, now that its uploaded that picture is scaled too small to read easily. Lets try adding this:

[Krieger]

Good work. What year is your box. I have an 99 and wondering if these part #s are good for me too.

[78F350]

Originally Posted by Krieger

Good work. What year is your box. I have an 99 and wondering if these part #s are good for me too.

That one is an 01. For the part number, check the Catalog.

The SAI is in the table of contents Under:
Main Group 1: Engine > 108: Air Injection System.

In the remarks column on the right, there are notes. -99 means through model year 1999, etc.