Hello!
Question about car - 2007. VW Golf 5 GTI , 2.0 TFSI BWA engine Manual
Have P0171 CEL system too lean on car. While looking for causes found out that pumping the brakes while car is running makes the short term fuel trim spike to +25%. Many people are saying that brake vacuum check valve is the cause, see image.
Question: In which direction should the air be restricted in this image and which one should be open.
I can say that blowing air into 1. part is blocked by the valve, not receiving air in 3. or 4. exit. However I can blow into 3. and 4. and receive air out of remaining 2 exits. Is that normal?
