Vacuum leak

[Terry.Reese]

So I occasionaly have this vacuum leak so I think i may an issue somewhere down the line that I cannot quickly see, I replaced a bit of tubing at one point with fishtank hose and fixed the problem. BUT, the plastic on the original piping is very brittle. My idea which I am going to post a original vacuum line for the 2004 4.2l B6. My idea is to rebuild a new line with more flexible hose. Thoughts?

Original line which I can by used for about 20-30 bucks.



or I can rebuild it with a similar type hose




I keep getting a lean bank code, if i remember correctly it is P0171 System Too Lean (bank 1) My MAF is only 6 months old also. Bosch

Thanks.

[bmwpower603]

Did you tighten your intake manifold bolts? Those come loose.

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[SlickFix]

Sure, why not. I used silicone line to replace all the vacuum lines on my B6 A4 Avant, and that's been going strong for years.

[jakeoboy67]

Did you tighten your intake manifold bolts? Those come loose.

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check this first , if you had a vacuum leak in some random vacuum hose, it would affect both banks ,
and you only have a code for bank 1.

[Terry.Reese]

Thanks, I will do both, but first I will tighten the intake manifold bolts.

[bmwpower603]

Thanks, I will do both, but first I will tighten the intake manifold bolts.

Did your ITM bolts end up being loose?

[Terry.Reese]

I am going to check tonight, looking for a new house with the wife and didn't get a chance. I will update tonight.

[Terry.Reese]

So tightened them up. A couple needed tightened slightly. Code hasn't popped up in a few days. So next is redoing the lines. And hopefully all will be good.

[Terry.Reese]

Popped the code again tonight. Same one.

[bmwpower603]

Popped the code again tonight. Same one.

They could have loosened back up. I would take all of them out. Use loctite. If that doesn't work. It could be some kind of exhaust leak.

I had the same issue. Never had the light come back on. But then again. 3 weeks later the car broke a main engine guide.

Currently the car is getting fixed :)

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[JimmyBones]

Popped the code again tonight. Same one.

Do you have intake manifold spacers? If not then get them and put blue locktite on the threads of the intake manifold bolts.

I say this because there was a TSB for that code and the intake manifold bolts backing out. The first step was to tighten the bolts and if that didn't solve the issue then Audi said to replace the intake manifold gaskets. If you are replacing the gaskets then it makes sense to get intake manifold spacers while you are in there.

Worst case, the intake manifold is warped and you need to put sealant/RTV between the cylinder heads, gaskets, and intake manifold. It was rare but that did happen, especially if you sit in rush hour traffic for prolonged periods of time or any situation where the intake manifold gets really extremely hot for long periods of time. Well I should say that it gets hotter than normal for long periods of time because there V8s do run hot as hell normally.

[Terry.Reese]

manifold spacers? no idea, not even sure what they look like, I have changed the gaskets on the valve covers and that is it. sorry not meaning to be the newb here, TSB?

[JimmyBones]

manifold spacers? no idea, not even sure what they look like, I have changed the gaskets on the valve covers and that is it. sorry not meaning to be the newb here, TSB?

JH Motorsports sell intake manifold spacers for these B6/7 S4s. They raise the intake manifold up so that it stays cooler while driving. They look like this:



Here is a link: https://jhmotorsports.com/shop/catal...h=21_56_61_240

TSB stands for Technical Service Bulletin. It is like a Audi published service circular to help diagnose common issues.

If you have any other questions then please ask.

[Terry.Reese]

Thank you very much for the info. I will look into these next. Much appreciated!

[Terry.Reese]

So initially I went in and tightened the incorrect bolts, I did the star ones, I kept throwing codes still, I then went in the light..(duh) and the Allen head bolts were all loose, I tightened them up and I could feel a better response almost immediately. I am currently putting money aside for the JHM spacers and gaskets and going to replace them all along with the vacuum hoses. Thank you all for the directions and assistance.