Bad turbo?

[B6_A4_Kid]

My bros b6 a4 1.8t Quattro is not boosting at all. We threw a new diverter valve in it and made sure it was the right way, that didn't help anything. Then we did the vacuum leak test. It does seem to be leaking near the kombi valve area, but it's not throwing a cel. The car is completely NA right now, not sure what to do next. When driving you can't even hear the turbo spool. I am thinking it could be the n75 because it's not throwing a code. I have vcds lite and there is nothing coming up and his dash is clear. Not sure if it makes a difference but his a4 is at 156k. Thanks in advance

[old guy]

It could be a sticking N75. A quick way to check out the DV and wastegate is to clamp off the N75 boost signal line that connects the N75 to the turbo wastegate. You should see an immediate change in the boost. As in full boost right away. If it doesn't happen you are either dumping boost somewhere in the boost track or the wastegate is stuck open.

[B6_A4_Kid]

Which is the boost signal line?

[treysgreen]

[customa4]

The one that says "Turbo (Boost)"



You can use a fuel line clamp like this to clamp off the line. Click



When you do this you will have unregulated boost since the N75 can't control it. Take it easy if you don't have a boost gauge to monitor the PSI, don't want to overboost.

[B6_A4_Kid]

Well we gave that a shot and it's definitely spooling, but now we it spoils it literally sounds like he has an ewg. Is that what happens when you clamp off the line, or is there something wrong with the waste gate on the turbo?

[old guy]

Help me out a little here. What does an ewg sound like?

[B6_A4_Kid]

Like a flutter sound under acceleration. Only when boost comes on, the difference is an external waste gate really only opens up at WOT or close to it. The was happening when boost barely started to kick in and it continued to do it until we let off.

[old guy]

External Waste Gate. Sorry.... missed the acronym.

So N75 in place no boost. Clamp off the boost signal hose to the N75 and you get some boost but a fluttering sound.

I'm speculating that you have a defective/broken spring or a split diaphragm in the waste gate.

[B6_A4_Kid]

That was my bad, I should have been more specific. So does this mean he needs a whole new turbo? Or is this a part we can just replace? Thanks

[old guy]

That was my bad, I should have been more specific. So does this mean he needs a whole new turbo? Or is this a part we can just replace? Thanks

The wastegate can be replaced separately.

[B6_A4_Kid]

If we get a new n75, but don't get around to getting a new wastegate for a few months. Is that going to hurt anything?