I think I narrowed down my P1128 CEL issue. I looked at every vacuum single hose and all were replaced last year except this one which I inspected at the time and thought it was OK. However it looks to be broken enough to let air pass.

Here is the top of the engine view:



The vacuum hose from the check valve (circled in blue) goes under the plate and connects to a T. That T then connects to the suspect hose which looks to me like it has unraveled and has come apart. In the pic below, the hose from the check valve is on the right coming down and goes to the suspect hose below the T:



Anyone know if that suspect hose can be replaced easily? It looks to be metal crush-clamped on both ends. I need to replace that and wondering it a new replacement hose is needed or can a simple hose the correc ID fit?

If I remove the check valve and blow into that hose going into the T, air passes right through that sucker. I just don't want to take it apart to inspect to find out I need to remove the item right behind it to even get at it. Hoping just the correct fitting hose without crush-clamps will fit. Or even small screw clamps I suppose can work.

1998, 2.8L, 30v quattro.

 

just go to autozone and get some hoses, its really easy. im pretty sure your "suspect" hose goes into the fuel pressure regulator (to the right of the fuel rail)

 

but if its the braded hose its the vacumm resevior (the blue thing that looks like a smurf boner) and all of these are easy to route. if your system has never been changed id just re do all of them.

 

In the second pic, it is the hose with the red arrow pointing to it. All other system hoses are all new.

The suspect hose is about 2" long (best guess) and has 2 crush-clamps on each end. On the top oo the hose goes into the T-connector. Before I yanked out the suspect hose to try and replace, I wanted to know if there was a male fitting on the lower end that the hose clamps around and if I could get to that.

I am looking to get an idea of what it is before I yank it out.

 

Ended up being easier than I thought. Yanked out the old hose and replaced. Oddly enough it was just the sheath around the hose that was falling apart. The actual rubber inner section was in tact. Still replaced it though. Now a wait and see game.

Another question on the blue/black check valve (near blue circle int he 1st pic). I assume air/vacuum only flows in one direction on this. It takes a good amount of force to push air through this thing using my mouth to push air through. Should air easily pass through this thing or is it supposed to be tough to get air through? As in is it set up that way or should air pass with no resistance in one direction?

 

The hose below that T goes directly to the intake manifold just after the throttle body. At the T, one side goes to the fuel pressure regulator and the other side goes to the check valve you have circled. The other side of the check valve then routes to several things your engine uses vacuum for and it goes to the vacuum reservoir. The check valve prevents the vacuum reservoir from venting back into the intake manifold. Not sure how difficult it is to blow/suck air through though.

 

Also check all the lines that were previously replaced. I had cut one line too short when I did mine and over time it wiggled around and got crimped under something, restricting vacuum flow.