Hey guys,

Newbie here, Yesterday I was coming home and realized the check engine light was on. I went to have it scanned and it picked up p0171 code too lean bank 1, also through a p0507 for idle. I also noticed today that there is suction coming from the oil dipstick and I can not get the oil cap off when the motor is running. I also noticed that the oil dipstick is not sealing very well and I have some oil on top of my hood inside. Now I don't know for sure if it's coming from the dipstick or not but to the best of my abilities from tracking the spray pattern it's where the oil is spraying from, but I could be wrong. Could anyone help me with this please? It's a 2004 A4 cabbi with 50k on it. The car DOES NOT have a rough idle and drives fine except for some bogging at stop lights and also when Im on the highway I can tell it loses power from time to time. Thanks in advance.

 

16555
P0171
Fuel Trim,Bank1 System too Lean
16891
P0507
Idle Control System Higher than Expected
Well there is pressure in the crankcase and under the valve cover when the engine is running so it should be a little harder to remove the oil cap when its running.
You got yourself quite a large vacuum leak, probably from one of the vacuum check valves. They look like a mini brake booster thats grey and black. Listen around the engine when its running and see if you can pinpoint where the sucking noise is coming from. This is a 1.8T i take it?

 

Hey thanks for the response sir. Yup I apologize for not including engine size. It is the 1.8. How many check valves are there and where would they all be located? Are there any diagrams? I did check for hissing noises but it could also be the internals of the check valve that went south too huh? Wonder how much it would cost to just replace all the vacuum hoses at T's and check valves you think?

 

There are three of them, one is near the air box, one is behind the motor, and the other one is by the intake manifold. All of them are hard to see LOL. The check valves tend to actually break off, or they wear a hole in them, so you should still be able to hear a hiss. If you buy regular $4 universal check valves instead of the $30 audi ones and buy about 15ft of vaccum line it should only cost you around $50 to replace them all. There is also the suction jet pump http://www.ecstuning.com/Audi-B6_A4-...ake/ES1891983/ (see link) and other lines like these http://www.ecstuning.com/Audi-B6_A4-...Engine/Intake/ which would bump your project budget up a bit. I would also clean the MAF sensor with some MAF cleaner to make sure thats not the problem.

 

Edit: double post