17924 - Intake Manifold Valve (N156) : Open Circuit

[ulfilias]

Hi Guys,

After playing with spark plugs, coil packs and miss fires (see here) which turned out to be a dodgy coil pack, though it had been replaced less than 100miles before!

I now have a new error in VAG-COM -

17924 - Intake Manifold Valve (N156) : Open Circuit

Any ideas ??? Have I knocked anything I shouldn't have, what is this and how does it effect the car as it seems to be running pretty well (I have a long trip Wednesday). Any suggestions ???

Thanks,
Lee

[David's8]

Rosstech wiki states:

http://wiki.ross-tech.com/wiki/index...4/P1516/005398

17924/P1516/005398 - Intake Manifold Valve (N156): Open Circuit
Possible Causes:
1. Wiring from/to Intake Manifold Valve (N156) faulty
2. Intake Manifold Valve (N156) faulty
Possible Solutions
1. Check/Replace Intake Manifold Valve (N156)
2. Perform Output Test.
3. Use Scope to check Activation Signal while performing an Output Test.

[ulfilias]

Hi David,

I'd seen that from this thread - However that assumes you know how to do an output test!!!

I did find this PDF which describes how, albeit on a 40v A8 rather than an S8. However that also mentions various VAG gear that i'm guessing VAG-COM replaces to some extent.

I have however found this rather useful thread with lots of pictures and diagrams and have gotten my head arround what it is and what it does.

Popping the bonnet and grabbing a friend, I've just checked if the bellows are doing their stuff. They are fully closed when just idle and playing with the loud pedal round 5-6k rpm they release, which seems to be what they are supposed to do. I did have a fiddle with the cables and sensors arround that area, unplugging and replugging as well. Clearing the code and it seems to have gone, so i'll see what happens on a ride out later.

Reading through things, it seems you get a bit more torque or pepp from the engine at low and high revs, depending on the pathways. Neither of which should cause any major show stopping problems!

Lee

[Architex_mA8tey]

If you need the manifold flaps and hinges refurbing then pm Guy (daviesbike) on here as he is doing them regularly

[David's8]

Yes the audi world thread is good on the subject. Though from what you say they are both operating in the 5-6k rev range. the first (middle speed range valve) should open at 3360rpm and the second at 5200 rpm from what I understand.

[ulfilias]

David,

The A8 40V has a 3 stage manifold (Both closed, one open, both open) the S8 has a two stage (both closed, both open) from what i've read, which is what mine is doing (it's a S8).

Lee