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I have a 98 a4 b5 2.8l quattro. I've notice when I start my car I hear a constant "PSSSSSS" from the rear and it doesn't stop until I stop the engine. After investigation I found a broken steel vacuum? line that is pissing air. I have two pictures here and can't seem in all my efforts to determine what the line is and where it leads too.
I've deleted my resonator and upon removing the heat shield you can see in the photo the two brake lines run into the rear and this line which is very rusted is above the brake lines parallel. It runs up and over the sub frame and exits the top of the rear subframe near the rear of the muffler. Please help me identify this line and if possible a diagram for it and where it leads to in the rear of the car. Thanks!
This POV is behind rear tire looking up into sub frame between back of muffler.
You can see with the resonator heat shield removed two rear brake lines. Above the two lines is another thicker line. Maybe .375 dia? This line is unknown to me and the one i'm asking you all to help me identify.
Shot in the dark... What about the vacuum line for the trunk unlock? Could make hissing noise if it is leaking yet not affect the car engine performance? Not sure of the routing of the line but this makes sense otherwise. Having any issues with the door or trunk locks?
Fortunately in the 29 years of owning Audi (1985 4000 Quattro was my first, on #8 now) I have never had a problem with the central locking system. Just thought they were vacuum based. Oh well.
Glad you found a way to enter this new piece of diagnostic info.
How about fuel system then? Check out a diagram that shows the evap system. Just googled this and found all sorts of diagrams showing a line going from the tank to some sort of charcoal canister. Seems like there ought to be lots of posts available to one who searches appropriately.
yea its becoming a pain. I'm very capable of diagnosing and repair my car as I always have. I'm at the point where I've contacted Audi in my local area to try and identify this line.
It runs out of the bottom of the driver side floor panel right near the inner fender. from there the line tucks into the chassis tunnel along side the brake lines as you can see.
I'll keep thinking about it and searching. I'm just trying to do it with out tearing my car apart.
P1476 is the code "leak detection pump low voltage" I've searched for diagrams and Haven't seem to come across any I can use. Your help is much appreciated
..with cars in general is some of them add pressure (or vaccuum) to the fuel tank (probably just for emissions purposes), and when your gas cap doesn't seal correctly, it can throw on a check engine light. I have a '96 A4, and I'm not sure whether or not our cars use these systems, but I know they have a charcoal canister system (emissions, to regulate/burn fumes escaping from the fuel), and there has to be some way of getting fumes out of the tank... a fat vaccuum line running from the tank to the system up front...? Good luck, hopefully I helped somehow!
10-12-2014, 10:13 AM
Please help me identify broke chassis vacuum line
