Vacuum leak Audi A4 V6

[foretshaun]

I've got a problem with my Audi 2.4 V6 that's driving me crazy,
the check engine light is on and I've got the fault codes P0171 and P0174 which are the so-called "lean codes".
I have been searching for a vacuum leak by spraying on a couple vacuum lines with some starter fluid/gas to see if the engine "coughs" but without further success.

So does anyone know any typical spot where there could be a vacuum leak or if there might be something else that's faulty? Like the MAF or anything alike?

I don't have English as my mother tongue FYI, so I'm sorry for any spelling mistakes etc.

All/any help is highly appreciated!

[SJorge3442]

I've got a problem with my Audi 2.4 V6 that's driving me crazy,
the check engine light is on and I've got the fault codes P0171 and P0174 which are the so-called "lean codes".
I have been searching for a vacuum leak by spraying on a couple vacuum lines with some starter fluid/gas to see if the engine "coughs" but without further success.

So does anyone know any typical spot where there could be a vacuum leak or if there might be something else that's faulty? Like the MAF or anything alike?

I don't have English as my mother tongue FYI, so I'm sorry for any spelling mistakes etc.

All/any help is highly appreciated!

Firstly, your english is spot on, so keep up the good work!

I would say your leak is being caused by one of the following.
Bad intake manifold gasket
Bad PCV lines
Bad MAF.

I had the same codes on my 3.0 and after changing my intake manifold gasket, cleaning my fuel injector o-rings and replacing my PCV lines, the codes have gone away. You can measure the maf's quality via ECU logging software such as VCDS or Torque Pro for android.

[foretshaun]

Firstly, your english is spot on, so keep up the good work!

I would say your leak is being caused by one of the following.
Bad intake manifold gasket
Bad PCV lines
Bad MAF.

I had the same codes on my 3.0 and after changing my intake manifold gasket, cleaning my fuel injector o-rings and replacing my PCV lines, the codes have gone away. You can measure the maf's quality via ECU logging software such as VCDS or Torque Pro for android.

Thanks a lot! I will take a look at those things, hoping for the MAF or a PCV line!

Is it difficult to change the intake manifold gasket and how much vacuum should the Torque app measure at idle?

[SJorge3442]

I've always been told that 18-25psi at idle is normal. I'm not at all familar with the 2.4 V6 but looking at some Google Images, it looks very similar to the 3.0. Removing the intake is as easy as removing the fuel rails, vacuum lines, pcv lines, and throttle body. You may have to remove some other pieces to make room to slide it out. You can try spraying starting fluid around the base of the intake to check for leaks, but since you cant get to the inside edge of the manifold, the leak might not be visible/reachable.

[ADCS]

The torque app is not measuring vacuum. It is interopalting it. It is probably good enough to detect a problem (large delta from what you typically see with the app) but I wouldn't use it to get an accurate reading of vacuum.