hyphenf15

What is the proper test for the cut off valve that runs inline from the secondary air pump to the SAI valve. I have the SAI valve off the car and need to pull a vacuum on the cut off valve but I don't know how it works. I've tested the vacuum with both ends open and it does not hold. If I plug both ends of the valve then it holds a good vacuum. Can somebody tell me the proper test for the cut off valve. Does it hold a vacuum to pull the SAI diaphram up/closed???

AOW162435

Greg,
I'm not sure how to answer your question, but if you need any parts, I'm selling my entire SAI system on Ebay at the moment. Clean as a whistle!


Andreas

hyphenf15

good luck with the sale. Anybody know how to test the cut off valve. Part number 993 113 245 00.

hyphenf15

bump - if I only try one end or the other it does not hold a vacuum. Anybody have an idea?

hyphenf15

According to the 993 essential campanion book there is an electronic solenoid valve the removes the vacuum pressure from the cut off valve allowing air from the air pump to pass to the SAI valve and into the engine. I'm making an educated guess that the cut off valve I have is bad because it won't hold a vacuum on the exit side of the cut off valve. If anyone can confirm or deny my educated guess before I spend $100 on a cut off valve that would be mucho appreciated.

hyphenf15

Anybody have the answer?

hyphenf15

OK. After a bit more hands on work with a vacuum gauge and vacuum hand pump my son and I figured it out. The vacuum is only pulled when the secondary air system is turned on during the first minute of engine start. When the vacuum is pulled, the cut off valve is opened allowing air from the pump to enter the SAI valve and the engine. When the pump and relay turn off after 1 minute, the diaphram in the cut off valve closes and no air passes through the cut off valve.

We tested this with the cut off valve by pulling a vacuum and blowing through either end with air passing through the valve. Without a vacuum you cannot get any air to flow through the valve. So the valve I have is good. Saved $100 bucks. And the bad SAI valve has been replaced and the manifold was cleaned as well. So time will tell if the ports are too clogged to allow enough air into the exhaust during start.