No boost!?

[jacobsen]

Yesterday I replaced the turbo exit gasket and I put a new mass air flow sensor on the air box and a new n75 with oem hoses. Before I had an exhaust leak at the turbo exit gasket and it was stinky and pretty sure it cause the motor not to boost very much. I assumed replacing those three items would make the car run right again. But in fact the car has less boost than before with the Leaky gasket. I'm stumped... Paging og or diagnosticator.

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[old guy]

First make sure your N75 is fully connected to the harness plug. If it isn't connected you will not be able to boost past the wastegate pressure.

[jacobsen]

First make sure your N75 is fully connected to the harness plug. If it isn't connected you will not be able to boost past the wastegate pressure.

When I plugged it in it went qlick so I thought I had it all the way in. I'll check it again.

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[old guy]

You should also go ahead and reset your ECM in case you have a DTC causing a lack of signal to the N75.

[jacobsen]

You should also go ahead and reset your ECM in case you have a DTC causing a lack of signal to the N75.

I tried unplugging the battery for a minute, should I unplug it longer?

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[old guy]

That's probably not long enough. Leave it unplugged for at leasr 15 minutes. Do you have any way to monitor your ECM? VCDS, TorquePro, etc?

[jacobsen]

That's probably not long enough. Leave it unplugged for at leasr 15 minutes. Do you have any way to monitor your ECM? VCDS, TorquePro, etc?

I have a torque dongle but it stopped responding when I tried to change its default password a year ago. So it's a brick. I need a new one. I have the torque app but no vcds or anything like that.

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[old guy]

Do you have a ELM327 to connect TorquePro through Bluetooth?

[jacobsen]

Do you have a ELM327 to connect TorquePro through Bluetooth?

Exactly, but it bricked a year ago and it won't respond or appear Bluetooth search.

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[old guy]

Too bad. You could have used it to reset your ECM. Try the battery reset and see if it makes a difference. Meanwhile are you sure your DV is functioning properly? Confirm that the vacuum/boost line from the intake manifold to the DV is intact.

[jacobsen]

Too bad. You could have used it to reset your ECM. Try the battery reset and see if it makes a difference. Meanwhile are you sure your DV is functioning properly? Confirm that the vacuum/boost line from the intake manifold to the DV is intact.

The n75 is plugged in. I unplug the battery for 30 minutes. I checked all the hoses. The diverter valve is properly connected and the hose is ok. Still this problem persists. What the heck is going on with my car...

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[old guy]

Clamp off the hose connecting the N75 to the wastegate to prevent the boost signal from reaching the wastegate. Take it for a gentle spin around the block and see if you can obtain boost. If you cannot obtain any more boost the problem could very well be a wastgate issue.

[jacobsen]

Clamp off the hose connecting the N75 to the DV to prevent the boost signal from reaching the wastegate. Take it for a gentle spin around the block and see if you can obtain boost. If you cannot obtain any more boost the problem could very well be a wastgate issue.

I have the n75 hooked up and the APR diverter valve hooked up so that the Boost comes on right away rather than gradually. So the hose from the intake manifold goes directly to the diverter valve. So how can I perform this test with my motor set up this way?

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[old guy]

It shouldn't matter how your DV is hooked up. It sounds like you have simply bypassed your N249 underneath the intake manifold. The N75 should have a hose connection to the high pressure port on the outlet side of the turbo and another hose connection from the N75 to the wastegate. Clamp that one off that connects from the N75 to the wastegate.

[jacobsen]

It shouldn't matter how your DV is hooked up. It sounds like you have simply bypassed your N249 underneath the intake manifold. The N75 should have a hose connection to the high pressure port on the outlet side of the turbo and another hose connection from the N75 to the wastegate. Clamp that one off that connects from the N75 to the wastegate.

Alrighty, I'll give that a shot. It's my grandparents 71st wedding anniversary today so it will be a little bit later before I get to it. Thanks, ill report back later.

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[old guy]

71st wedding anniversary?? Wow! Tell them Old Guy says Happy Anniversary!!

[jacobsen]

71st wedding anniversary?? Wow! Tell them Old Guy says Happy Anniversary!!

They are a testament to what's possible if you really care about what you're doing. They set a very high example! Apparently my girlfriend's grandparents have been married for 74 years. Can you imagine? I noticed my old n75 is 05890 6283 C and my new n 75 is 06890 6283 e. Does this spell a problem? I believe I was told to get revision C I'm going to go out and try to clamp the wastegate hose now. Somehow I can't help but wonder if the second open port on the wastegate is causing this. I felt like I should cap it off or close it somehow but other members recommended that keep it open.

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[jacobsen]

I replaced the new in 75 that was a uro brand with the original OEM with the Audi symbol on it. The Boost is much better than before. But not as good as it has been.

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[old guy]

Somehow I can't help but wonder if the second open port on the wastegate is causing this. I felt like I should cap it off or close it somehow but other members recommended that keep it open.

You are running a K04, correct? I am not aware of a second wastegate port on a K04. Is it something different than a standard K04?

[jacobsen]

You are running a K04, correct? I am not aware of a second wastegate port on a K04. Is it something different than a standard K04?

I was confused by the second port on the wastegate actuator as well. Traditionally you have the wastegate on a 90 degree Bend facing the passenger side where the input to the n75 goes. This one has that. But it also has one which is facing the driver side. I did remark about this on the forum here but other members suggested I leave it open. I thought that was peculiar. My first inclination was to cap it off with a piece of silicone hose with a screw zip tied into the end.
And yes this is a ko4 correct part number.
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[old guy]

So where on the wastegate is this second port? I'm still confused.

[jacobsen]

It's facing the opposite direction as the one you see and instead of being built into the top side like that one as it's built into the side. To be honest I didn't get many responses on my question about it before and not only am I confused but it seems like everyone I talk to about it is confused. But it was explained to me that it is for some secondary function on newer cars.

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[jacobsen]

I thought about getting an adapter and connecting them both to a 3 Way T Junction and connecting that to the n75. But I think at the moment I'm going to let the motor cool off and try to reach down and plug it.

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[jacobsen]

I just discovered while rummaging around around the n75 that the tip is barely resting on the compressor side of the turbo, somehow it back it's way off. I guess I need to tighten it back down... How did this happen...

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[old guy]

If the second port is on the side of the wastegate and below the internal diaphragm you are going to want to leave it open. Otherwise you will be adding pressure to both sides of the wastegate diaphragm.

And the more I think about it that second port must connect on the back side of the diaphragm. Otherwise it would be completely redundant. I don't know what it is for but it wouldn't make sense to have it be otherwise.

[MoparFreak69]

It's probably a dual acting actuator. Meaning it can probably be used on different turbo applications that may require the diaphragm to either push or pull on the rod.

[jacobsen]

Well I put my finger over it while the car is running before and it's sucking air. So it's some kind of vacuum leak one way or the other.

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[MoparFreak69]

The diaphragm is probably torn inside of it.

[diagnosticator]

Well I put my finger over it while the car is running before and it's sucking air. So it's some kind of vacuum leak one way or the other.

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The wastegate actuator port on the opposite side from the normal port, must be OPEN, not connected to anything or capped.

There is something wrong with the vacuum system plumbing if there is vacuum at the opposite side actuator port. For this to occur, the control pressure hose from the N75 must be at vacuum pressure with the engine idling, and the diaphragm must be split so that the vacuum pressure can be applied to the other side of the actuator diaphragm. In order for there to be vacuum from the N75 to the actuator, the N75 control pressure source connection must be incorrectly connected to a vacuum pressure source instead of the compressor housing volute.

The N75 control signal source is incorrectly connected to a vacuum pressure source, and the diaphragm in the actuator is defective.

[diagnosticator]

Clamp off the hose connecting the N75 to the wastegate actuator to prevent the boost signal from reaching the wastegate. Take it for a gentle spin around the block and see if you can obtain boost. If you cannot obtain any more boost the problem could very well be a wastegate issue.

Replaced DV with wastegate actuator.

[diagnosticator]

I thought about getting an adapter and connecting them both to a 3 Way T Junction and connecting that to the n75. But I think at the moment I'm going to let the motor cool off and try to reach down and plug it.

Do not connect anything to that port and do not plug it with a cap. the port must be open.

[diagnosticator]

I was confused by the second port on the wastegate actuator as well. Traditionally you have the wastegate on a 90 degree Bend facing the passenger side where the input to the n75 goes. This one has that. But it also has one which is facing the driver side. I did remark about this on the forum here but other members suggested I leave it open. I thought that was peculiar. My first inclination was to cap it off with a piece of silicone hose with a screw zip tied into the end.
And yes this is a ko4 correct part number.
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Is the second actuator port that is pointing toward the driver's side, on the same side of the actuator can as the port pointing to the right, or on the opposite side of the actuator can?

If it is on the same side of the actuator can, then the port pointing to the driver's side must be capped.

[jacobsen]

Is the second actuator port that is pointing toward the driver's side, on the same side of the actuator can as the port pointing to the right, or on the opposite side of the actuator can?

If it is on the same side of the actuator can, then the port pointing to the driver's side must be capped.

https://youtu.be/eTletmBNxsA

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[jacobsen]

I have everything buttoned up again and I just took it for a spin and it's a little bit better than before with the tip snugged down. But it's not where it should be. I'm going to disconnect the battery for while and try it again.

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[diagnosticator]

The wastegate actuator shown on the K-04 in the video, has a sealed actuator rod at the housing pass through. Therefore the second port is the vent for the actuator housing. If the actuator was used with an inverse pressure/vacuum control signal, the control pressure would be connected to the second port, and the normal port would be the actuator vent. If the actuator was not vented, the diaphragm could not move properly with varying control pressure, because the air volume on the vent side of the diaphragm would act as an air spring being trapped in the actuator housing.

[jacobsen]

The wastegate actuator shown on the K-04 in the video, has a sealed actuator rod at the housing pass through. Therefore the second port is the vent for the actuator housing. If the actuator was used with an inverse pressure/vacuum control signal, the control pressure would be connected to the second port, and the normal port would be unconnected/open being the actuator vent. If the actuator was not vented, the diaphragm could not move with varying control pressure, because the air volume on the vent side of the diaphragm would act as an air spring being trapped in the actuator housing.

I drove it for a couple of days with it plugged when I first got it. Then I took the plug off when I realized it shouldn't be plugged. And I felt the pull of suction does that mean the diaphragm is bad?

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[diagnosticator]

I drove it for a couple of days with it plugged when I first got it. Then I took the plug off when I realized it shouldn't be plugged. And I felt the pull of suction does that mean the diaphragm is bad?

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If there is vacuum pressure at the actuator vent, then there must incorrectly be vacuum applied to the control pressure port at the actuator from the n75 and the diaphragm must be defective or the vacuum pressure could not pass the diaphragm to be present at the actuator vent.

Sometimes faulty parts escape being noticed during manufacturing.

Test the actuator by using a hand vacuum pump connected to the normal control pressure port. The actuator must hold whatever vacuum pressure is applied without leaking off.

[jacobsen]

If there is vacuum pressure at the actuator vent, then there must incorrectly be vacuum applied to the control pressure port at the actuator from the n75 and the diaphragm must be defective or the vacuum pressure could not pass the diaphragm to be present at the actuator vent.

The middle port is connected to the compressor side of the turbo. The long side is connected to the tip. The short side is connected to the actuator. The diverter valve is connected to the intake manifold. It sounds like my next mission is to confirm that there is suction at the vent? It's merely vent to allow the diaphragm or plunger inside the actuator housing to move freely is what you're saying? It's not actually supposed to be hooked up to anything, unless it was inverse, which sounds like it would be pressurizing it in the reverse function it set up and now.

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[diagnosticator]

The middle port is connected to the compressor side of the turbo. The long side is connected to the tip. The short side is connected to the actuator. The diverter valve is connected to the intake manifold. It sounds like my next mission is to confirm that there is suction at the vent? It's merely event to allow the diaphragm or plunger inside the actuator housing to move freely is what you're saying? It's not actually supposed to be hooked up to anything Kama unless it was inverse, which sounds like it would be pressurizing it in the reverse function it set up and now.

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All correct.

If the N75 is correctly connected, there is no way for vacuum pressure to be applied to the wastegate actuator. Confirm the presence of vacuum pressure at the actuator vent. Normally there can only be ambient outside atmospheric pressure on the vent side of the actuator diaphragm and at the vent port. There is no way for there to be vacuum pressure applied to the actuator at the control pressure port from the N75.

The only situation where vacuum could exist at the actuator, if the compressor housing is below ambient air pressure. That would require a major blockage in the intake system plumbing before the compressor.

Test the actuator by using a hand vacuum pump connected to either the normal or second/inverse control pressure port. The actuator must hold whatever vacuum pressure is applied without leaking off.