I have a problem with my EGR system, I have a newly purchased 1997 Subaru Outback limited, High miles 175K, 5-speed, 2.5L, 4 Cyl. Started off I would get the Check engine light with a code P0400 stating EGR flow problem. System consists of BPT(Back Pressure Transducer), Control Solenoid, and EGR valve. I have done all the tests in the manual. Checked all hoses, the valve functions properly with hand pump applying 10 in. of pressure, and passes diaphragm check. Solenoid has the battery voltage and 41 ohms resistance, within the 10 to 100 range. I have replaced the BPT since the old one I thought was not operating correctly, and everything else checked out. With a vacuum gauge at the valve hose it shows the initial spike in vacuum of 12 then drops to 2-4. However when the cover to the BPT is opened and the little white fuzzy thing is removed there is a round maze looking section with one little hole going down into the main body. When I plug this hole the whole system operates correctly, valve moves and stays, and adjusts with different RPMs. This hole is supposed to be there and the white fuzzy will allow air in at a low rate, plus there are two small holes at the top of the cover so air will be able to get in; the old one smells of gasoline and exhaust. Now I get two codes P0400 and P0325 a knock sensor #1. I do most all of my work and am baffled along with my buddies and mechanic friends, any help would be great.
