Boost issues

[Gabriel_]

Before I get stared, I've reserved this issue for a few das now. I've got a p0229, I did the SAE delete, as well as a new TIP, and forge DV. But ever since I did the delete I've had the under boost code. I don't have any vacuum leaks. I pulled the vacuum line off the waistgate to see if maybe the turbo was bad it boost's fine. I replaced the N75, N249 (even though is blocked off) tried changing the vacuum diagram so it's a little more like stock, still nothing....

I guess my 2 questions are is it possible my waist gate actuate is going bad and opening with very low boost?

And dose anyone have any other ideas?

[diagnosticator]

Why did you remove the SAI? If you understood what SAI does, and how, you would most likely not be having this problem since you probably would not have removed the SAI. There is no practical benefit from removing the SAI, and now you have new problems that did not exist before. Regardless, removing the SAI has created a plumbing problem somewhere in your vac and/or boost control systems. A failed wastegate actuator can't cause the wastegate to open early. That would cause the WG to open late or not at all. If the wastegate is sticking open or has a hole burned in the valve disk that will cause low boost, the fact that it started happening right after removing the SAI is most likely not just a coincidence because the arbitrary failure of something related to boost control at the same time the SAI was removed is very unlikely.

[Gabriel_]

Wow your so smart of course the problem happened form the SAE delete. I replaced that that stuff because it either tested just a little off or looked old/rustic. I deleted it because the SAE system on audis is for one crap. Plus I also have a b5 that I set up with a gtx2871r that I also deleted the system, and didn't have any problems with. I plan on doing the same with this car by ko3 since it's a day ly driver. But then ran into some problems.
No need to come in here being a dick just because you love your stock sae system. And yes i understand what it dose and what is use is still dont like it. Thanks for the answer tho

[Let it snow]

Wow your so smart of course the problem happened form the SAE delete. I replaced that that stuff because it either tested just a little off or looked old/rustic. I deleted it because the SAE system on audis is for one crap. Plus I also have a b5 that I set up with a gtx2871r that I also deleted the system, and didn't have any problems with. I plan on doing the same with this car by ko3 since it's a day ly driver. But then ran into some problems.
No need to come in here being a dick just because you love your stock sae system. And yes i understand what it dose and what is use is still dont like it. Thanks for the answer tho

You just called one of the most knowledgeable, helpful and respected forum members a dick. You should not get much help after that.

[diagnosticator]

I questioned why you removed the SAI because typically guys who do this don't really know why the SAI is installed in the first place, and do so because it seams to be the popular thing to do. I don't know what you know or don't know otherwise. Your questions imply an incomplete background regarding how and why the various engine systems function as they are designed, including the boost control system. I don't love the SAI so much, I don't consider important engine equipment optional, and usually the decision to remove SAI suggests guys doing this think they know more than the factory does about engines. If your are fully aware of the technical aspects of the SAI, and that something about the plumbing is mis-configured from removing SAI, why did you post here? No offense intended.

[hightime80]

Wow your so smart of course the problem happened form the SAE delete. I replaced that that stuff because it either tested just a little off or looked old/rustic. I deleted it because the SAE system on audis is for one crap. Plus I also have a b5 that I set up with a gtx2871r that I also deleted the system, and didn't have any problems with. I plan on doing the same with this car by ko3 since it's a day ly driver. But then ran into some problems.
No need to come in here being a dick just because you love your stock sae system. And yes i understand what it dose and what is use is still dont like it. Thanks for the answer tho

What a douche'
Good luck getting your shit fixed now😉

[old guy]

Since your underboost code appeared immediately after you modified "whatever" I have to assume something is hooked up incorrectly. You mentioned an SAE delete and that you blocked off the N249. My assumption is that you are referring to the SAI (secondary air injection) system. Not sure about the blocked N249. If you could provide a better description and/or a few pictures of what you changed I am sure we can figure out what went haywire.

[Gabriel_]

I questioned why you removed the SAI because typically guys who do this don't really know why the SAI is installed in the first place, and do so because it seams to be the popular thing to do. I don't know what you know or don't know otherwise. Your questions imply an incomplete background regarding how and why the various engine systems function as they are designed, including the boost control system. I don't love the SAI so much, I don't consider important engine equipment optional, and usually the decision to remove SAI suggests guys doing this think they know more than the factory does about engines. If your are fully aware of the technical aspects of the SAI, and that something about the plumbing is mis-configured from removing SAI, why did you post here? No offense intended.

Im sorry i shouldn't have jumped right off the gun to assume you were being insulting. i apologize.

Since your underboost code appeared immediately after you modified "whatever" I have to assume something is hooked up incorrectly. You mentioned an SAE delete and that you blocked off the N249. My assumption is that you are referring to the SAI (secondary air injection) system. Not sure about the blocked N249. If you could provide a better description and/or a few pictures of what you changed I am sure we can figure out what went haywire.

So after carefully looking into the system, everything was hooked up correctly. i boost air tested the system checked fine, so i went ahead and smoke tested the system as well. it was also ok.

some history on the car, when i bought it the motor was blown. i did a complete rebuild on it, as well as completely going thought the suspension, as well as the interior. this car should have been taken to wrecking yard but i love fixing them and bring them back to life. this car runs amazing feels awesome. after the rebuild i didn't delete the vacuum lines/ SAI pump until i knew it was running ok. BUT i forgot i scanned the system before the delete and i had a under boost code, I'm can be away long periods of time for work so when i got back i completely forgot about it and did the delete.

with that being said i went ahead and put all the old vacuum stuff on it but since i went thought the trouble of putting it back on. theres no way I'm taking it off again, but i did get all new lines, check valves ..EXa... drove it still under boost. installed a boost gauge to see exactly what is going on I'm peaking at 6psi and holds. i went ahead and did another boost leak test.. nothing.. as well as a smoke test.. nothing. so with no leaks and all valves/ solenoids being new. theres only one thing left to try and that is a waist gate actuator test. tomorrow i will test the actuator to see when it begins to open. (the previous owner replaced the turbo with a new one) so I'm thinking the actuator just needs to be adjusted.

My question is, stock audi boost should be roughly like 10-12 psi correct?

[old guy]

You are correct. Stock boost should be in the 10→12 psi range tapering to around 7→8 psi at the top. Your problem is probably one of two things. The N75 circuit or the DV.

Either clamp off or disconnect the boost signal line that runs from the N75 to the wastegate. Take a quick drive around the block. If your boost comes back the problem will most likely be associated with the N75. If the boost doesn’t come back it may be your DV.

How is your DV hooked up? Are you running it through the N249 or directly to the intake manifold? An internal leak on the DV won't show in a boost leak test unless you disconnect the DV from the TIP and plug the TIP port. No air should blow through the open DV port when testing in that configuration.

[Gabriel_]

So I've already done That test, blocked off the N75 boost came back. I replaced the N75 and the problem still occurred. I though just maybe I got a defective part so I took the n75 race I have in my B5 problem still occured. Then I thought well just maybe my dv is bad so I replaced it with a forge one I had laying around. Yet problem still occured.

Dv is hooked to the n249, I try ed flipping it to streight to the intake as well, didn't change anything.

Here's the thread that got me thinking about the waist gate.

http://www.audizine.com/forum/showth...ate-Adjustment

Before I do this I am going to apply pressure to the actuator to visibly see what pressure it begins to open. I created a little tool to do it so I'll update tonight.

[Gabriel_]

So I went ahead and applyed a fixed pressure to the waist gate. It would start to open at 4 psi and fully open at 6psi. Adjusting it doesn't do much in my opinion. All it really adjusted is how much you want to waist gate open. Not the reaction time.. in my case.

So that was a failed attempt. Butt out of frustration I tool my (new) n75 which was peaking boost at 6psi. And put in the old original n75C and it held boost to 10.5psi.... it was still low enough to cause the check engine light to come on for under boost but a big difference.

I did allot of research on the different types of n75's from what I concluded the n75C was upgraded by audi to the n75J (correct me if I'm wrong). Thinking about ordering one of those but I'm kinda curios if maybe my waistgate spring is worn out and that is why it open early? Or just got at bad n75 and the original n75c is on its way out?