I opened the hood yesterday to discover this little tube had broken. Is this crucial and what is it? Thanks...

 

I believe thats the hose that attaches to the solenoid for your diaverter valve, if thats the case then yes it is important. I bet you have a code if you could check em. Might help if we knew the year of your car, i believe there are variations.

 

OK, thanks. It is a 2000 A4 Quattro.

Looking at some of the diagrams, it appears that it's a hose that connects the "recirculating valve for turbocharger" with the "intake manifold". This "recirculating valve for turbocharger" sits right next the the "secondary air injection solenoid valve" if that guides any further insights into this little problem.

Am I likely to notice a significant performance boost/efficiency once I get this replaced?

 

The recirc valve is the diverted valve - interchangeable terms. Once it's repaired the car will run properly.

 

yeah mine had a crack in it and ran SO slow... got a new one and car ran smoothly

 

Was it simply a matter of replacing the tubing? Or, is the break only symptomatic of something else that's quite likely gone wrong too? I know I've got to get codes, if there are any. I'm just anxious to get what I need for the repair, as I'm getting it looked at for something else early next week and would like to kill 2 birds before a long trip. Thanks..

 

no the tube is jsut bad, get a new one throw it on there BOOM youre done

 

He doesn't need to buy anything. He can cut the long piece to make a clean end and then connect it back. Plenty of slack there. Looks like someone already did it before. But put some clamps on that coupler.

 

So, if I'm reading things right, this is the tube that carries the vacuum from the intake manifold to the N249 solenoid (which in turn is connected to the DV) when the throttle body is closed so as to activate, or open, the DV when letting up on the gas. But, because the tube is broken and the vacuum cannot make it to the N249 solenoid and the DV, the DV would normally close due to the lack of vacuum. Instead, the DV is forced open anyway full-time by the ECU (limp mode) so as to prevent a build-up of boost. If I understand correctly, too much burst would occur without the intervention of the ECU because the vacuum lines cannot actuate the DV. Does that sound right to you more technically inclined out there? In other words, would having this vacuum line broken be enough to send the ECU into "limp mode"?

 

I believe it would be enough to send the ecu into limp mode. I also think that whenever the check engine light is on, the cars in limp home mode. Im not too sure if the dv is in the open position. I thought that it would be closed, because there is no vacuum to open it. Even if the solenoid is being operated by the ecu, there still is no vacuum to open the dv, so i believe its going to be in the closed position until that hose is replaced. I'm supprised theres not a check engine light with a vacuum leak of that size. Just replace the the hose from the intake to the solenoid, and all will be well, its a rediculously cheap hose.