What's this? Please.
05-01-2011, 07:59 PM
#16
Rennlist Member
The Porsche 993 Essential Companion explains the system in a couple of pages quite well.
It is a one-way valve allowing air to flow to the ports, but prevents exhaust gases to flow back towards the pump after the DME turns the pump off.
If it hasn't failed, a cleaning is all it needs.
I just cleaned mine last week. It wasn't causing problems but since I had it off, why not. Holding the ISV upright with the ports at the bottom, I used lacquer thinner and a small brush...I can't tell the unit has ever been installed.
It is a one-way valve allowing air to flow to the ports, but prevents exhaust gases to flow back towards the pump after the DME turns the pump off.
If it hasn't failed, a cleaning is all it needs.
I just cleaned mine last week. It wasn't causing problems but since I had it off, why not. Holding the ISV upright with the ports at the bottom, I used lacquer thinner and a small brush...I can't tell the unit has ever been installed.
05-02-2011, 11:39 AM
#17
Racer
Thread Starter
Mystery solved. :)
Thanks to all. 
Auxiliary Air Pump filter element seems to be the SAI check valve.
Porsche Warranty & Maintenance booklet on page 36:
48 000 km Service:
Auxiliary air pump: replace filter element.
Why Porsche calls the SAI check valve a filter element only the Gods know.
Rücklaufventil would be the correct German name.
Auxiliary Air Pump filter element seems to be the SAI check valve.
Porsche Warranty & Maintenance booklet on page 36:
48 000 km Service:
Auxiliary air pump: replace filter element.
Why Porsche calls the SAI check valve a filter element only the Gods know.
Rücklaufventil would be the correct German name.
