F21 Not boosting past 10 psi stage 3 630cc

[PsorianoPre99A4]

Just put in a stage 3 UM tune on my 99.0 1.8tqm aeb with an f21 kit nd only hitting 10 psi. Before i put the tune on I was hitting that same amount on my stock ecu. I just switched ecus that had um stage 3. I also have a 3" maf and 630cc injector installed. Could this be my wastegate actuator? Throttle body alignment? I know there isn't any boost leaks

[Tanzimur]

did you try removing the waste gate line from the n75 and driving around toeing into it while trying to get into boost? if not this test the waste gate to see if it is functioning properly. but watch the boost gauge and do NOT go WOT boost will just build and build till shes explodes. Heads up!

[zandrew]

Check that your n75 is functioning properly and hooked up properly. Also check your boost lines have no cracks and are in good shape.

[PsorianoPre99A4]

did you try removing the waste gate line from the n75 and driving around toeing into it while trying to get into boost? if not this test the waste gate to see if it is functioning properly. but watch the boost gauge and do NOT go WOT boost will just build and build till shes explodes. Heads up!

I have not tried that yet. The line that goes to the actuator from the n75? I did take that line off and used a boost tester on that actuator and I heard it start to crack open at around 5-7psi, when I think it should be cracking at 12 psi.

[PsorianoPre99A4]

Check that your n75 is functioning properly and hooked up properly. Also check your boost lines have no cracks and are in good shape.

I'd throw a code for n75 if not working properly right? Boost lines are good. No cracks anywhere.

[zandrew]

If the lines are not connected properly then you would not get a code.

If no codes the other thing to look at is the compressor cover seal. Is it missing, not installed properly, etc. Does the turbo boost to 10 lbs instantly like a K04 or does it take a second to get there and not go past 10 psi?

[PsorianoPre99A4]

Okay so I just tested something. I took off the hose between the N75 to the wastegate actuator and I was hitting boost spikes over 20psi, I was scared so I left off quickly. Does this mean by waste gate actuator is bad and is prematurely releasing the pressure?


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[PsorianoPre99A4]

Please help I need to figure out if I need to buy a waste gate


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[PsorianoPre99A4]

Any insight about post 7?


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[zandrew]

Hook the line coming off the compressor cover (positive boost) directly to the wastegate and see what it holds. This will tell you if the wastegate is healthy or not.

The wastegate should not hold boost infinitely with no boost signal going to it. Some will open at much lower setting then 20 psi with no signal at all. Do not read anything into that. Test it the right way and eliminate each possibility till you find what needs fixed.

[PsorianoPre99A4]

I don't think I understand the 2nd part of what you're saying. I took off the line that connects from the n75 to the wastegate actuator. And hit boost spikes up above 20-25 ish, I didn't hold it there though because I got scared. What other ways can I test to see what's wrong? I was thinking it's the actuator itself or I need a mbc.


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[PsorianoPre99A4]

did you try removing the waste gate line from the n75 and driving around toeing into it while trying to get into boost? if not this test the waste gate to see if it is functioning properly. but watch the boost gauge and do NOT go WOT boost will just build and build till shes explodes. Heads up!

I just tried this and the boost spike up to about 25 psi, but I left off quickly when I did that. What would that be telling me exactly? I did hold it at 15psi for 5 seconds before i went wot for 1/2 second. And again, this was while the line from the n75 to wastegate actuator unconnected. Someone please help, I need to decide if its the actuator and if I need to purchase a new one. Has anyone had any problems with there F21 actuator?

[MetalMan]

If you're seeing higher boost at all (with N75 line disconnected) then it's not the turbo or wastegate. This test proves that when the wastegate is left closed it stays closed and allows boost to build.

Standard F21 cracking pressure is 7-8psi. It's possible that yours could be set at 10psi.

So you have some more work to do, to determine what the issue is. There are a few possiblities, some may have been mentioned already in this thread:

1. bad N75
2. limp mode - scan for fault codes
3. bad N75 wiring
4. N75 hooked up incorrectly

[PsorianoPre99A4]

I made sure the N75 is routed correctly and it is. I will try to get a picture if I can. I also replaced it with a new n75 and same results. If it was wiring wouldn't a fault code come up? Which there isn't. And I also thought that AEB there is no limp mode? No code for that. I won't be able to get a good version of vagcom until the weekend .


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[MetalMan]

I made sure the N75 is routed correctly and it is. I will try to get a picture if I can. I also replaced it with a new n75 and same results. If it was wiring wouldn't a fault code come up? Which there isn't. And I also thought that AEB there is no limp mode? No code for that. I won't be able to get a good version of vagcom until the weekend .

If N75 wiring is bad you would probably get a fault code.
AEB is capable of limp mode, though it lacks many of the fault detection and whatnot that could trigger limp mode on AWM.

I believe with VAG-COM you can check requested boost; the value it reports will be in mBar. Take this value and convert to psi, then subtract ambient air pressure (usually 14.7 psi for sea level). The result will be the boost level your ECU is requesting, which obviously can be a useful tool for diagnosis.

Similarly, you can check N75 duty cycle to see how the ECU is attempting to control the N75.

[PsorianoPre99A4]

If N75 wiring is bad you would probably get a fault code.
AEB is capable of limp mode, though it lacks many of the fault detection and whatnot that could trigger limp mode on AWM.

I believe with VAG-COM you can check requested boost; the value it reports will be in mBar. Take this value and convert to psi, then subtract ambient air pressure (usually 14.7 psi for sea level). The result will be the boost level your ECU is requesting, which obviously can be a useful tool for diagnosis.

Similarly, you can check N75 duty cycle to see how the ECU is attempting to control the N75.

Thanks for the insight Metal, when I get a hold of another vagcom I will reply back to see what I come up with. How much will it cost for a version of vagcom that is capable of doing this? I want to get one for my car so I don't have to wait around for others to help me.

[Believer]

I didn't think aeb had a boost readout due to no MAP?

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[PsorianoPre99A4]

I didn't think aeb had a boost readout due to no MAP?

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I'm also throwing the code P1565 for throttle body adaptation. Throttle body isn't adapting correctly after switching ecu, could that be of an issue of why i'm not getting any power? Or is that just idle related?

[zandrew]

If you take the line coming off the compressor cover side that goes to the n75 and pull it and hook it directly up to the wastegate you will find out if the wastegate is working correctly and at what psi your wastegate is set at. The way you did only tells you if the wastegate is closed. However the wastegate arm can be out of adjustment and buying hooking the wastegate up directly to the compressor port it will tell you if the wastegate itself is setup correctly.

You keep insisting it's not the n75 and no codes. With it boosting over 20 psi disconnected it should not be the compressor cover gasket. This narrows it down to the wastegate unless you are missing something else. Trouble shoot the wastegate and either eliminate it or get it fixed. Your jumping from one thing to another without eliminating any part.

[zandrew]

If you still do not understand what I am saying look at this picture.

http://www.google.com/search?q=n75+h...TbGMsWhLaJM%3A

Take the blue arrow on the n75 and hook it directly to the green arrow. All wastegate have a psi setting them self. If you run the turbo this way it will tell you if there is issues with the wastegate itself.

[PsorianoPre99A4]

I think the wastegate could just need a readjustment.
By taking the blue arrow and connecting the hose or to the waste gate actuator?


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[PsorianoPre99A4]

What will it tell me exactly? Will the car run that way?


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[MetalMan]

I didn't think aeb had a boost readout due to no MAP?

You are partially correct; you don't get to see boost actual on AEB due to lack of MAP. But I'm pretty sure you can still see boost requested.

What will it tell me exactly? Will the car run that way?

As zandrew alluded to, by hooking the wastegate directly to the compressor reference your turbo will be operating on wastegate pressure. You can keep the N75 plugged in electrically and with its long nipple in the TIP.
By doing this, the turbo will spool up to whatever boost pressure the wastegate is set at, and then the wastegate will stay open. Boost should hold steady at wastegate pressure. It's a very useful test.

[zandrew]

When turbos were first installed on cars there was no boost controller. The port on the compressor side was hooked directly to the wastegate. The wastegate has a base setting. It could be 10 psi, 7 psi, hell 1 psi. I had a garrett gt2871r that had a 14 psi wastegate. Since your car is not going past 10psi there is a good chance the wastegate setting is 10psi.

If you hook the wastegate up as I suggested the car will run fine unless the wastegate is completely locked which it isn't since your not going past 10 psi. It will let you know if it's set correctly or not. If it's working correctly or not. It's a process of elimination, you should start with the wastegate itself.

The n75 works by blocking the boost reference psi until the desired psi is met. Let's say you turbo uses a 10psi wastegate actuator and you set the n75 too 8 psi. The wg will not open till it's 10 psi setting is hit. Let's say you set the n75 to 20psi. The n75 blocks the boost til you hit its 20 psi setting. Once it hits 20 psi it will allow the signal through the n75 and opens the wastegate. With the test I told you to do you eliminate the n75 from the equation and figure out if the wastegate is working correctly. Then you can move on to the next part.

[PsorianoPre99A4]

When turbos were first installed on cars there was no boost controller. The port on the compressor side was hooked directly to the wastegate. The wastegate has a base setting. It could be 10 psi, 7 psi, hell 1 psi. I had a garrett gt2871r that had a 14 psi wastegate. Since your car is not going past 10psi there is a good chance the wastegate setting is 10psi.

If you hook the wastegate up as I suggested the car will run fine unless the wastegate is completely locked which it isn't since your not going past 10 psi. It will let you know if it's set correctly or not. If it's working correctly or not. It's a process of elimination, you should start with the wastegate itself.

The n75 works by blocking the boost reference psi until the desired psi is met. Let's say you turbo uses a 10psi wastegate actuator and you set the n75 too 8 psi. The wg will not open till it's 10 psi setting is hit. Let's say you set the n75 to 20psi. The n75 blocks the boost til you hit its 20 psi setting. Once it hits 20 psi it will allow the signal through the n75 and opens the wastegate. With the test I told you to do you eliminate the n75 from the equation and figure out if the wastegate is working correctly. Then you can move on to the next part.

Ok thanks for the detailed response! I will try this when I get home today. Will my throttle body not being adapted and throwing the code p1565 do anything to the turbo, boost, or power?

[Believer]

Ok thanks for the detailed response! I will try this when I get home today. Will my throttle body not being adapted and throwing the code p1565 do anything to the turbo, boost, or power?

I don't know about the effect of that code but you should fix it to eliminate that as a potential contributor to your issues. Adapt the throttle body (VCDS group 60 iirc), clear faults, and go from there.

[zandrew]

The only other thing I could think the throttle body adaptation could do is put you in limp mode which would not allow you past 10 psi.

[Seerlah]

Dumb question but did you boost leak test, along with exhaust leak test with seafoam? Hitting 20-25psi could have been caused by overspinning the chra and creating compensation. Just something to look into. But you are in good hands and these guys won't lead you wrong.

[PsorianoPre99A4]

Dumb question but did you boost leak test, along with exhaust leak test with seafoam? Hitting 20-25psi could have been caused by overspinning the chra and creating compensation. Just something to look into. But you are in good hands and these guys won't lead you wrong.

I didn't do a boost leak test, but I have replaced all the hoses already. I already was boosting to 10 psi on my stock ecu and at around 20g at idle., which told me I didn't have any leaks.
What do you mean by overspinning the chra and creating compensation?

[MetalMan]

That doesn't indicate lack of a boost leak in my experience. You should definitely check for leaks.

[Seerlah]

What do you mean by overspinning the chra and creating compensation?

Meaning RPMs on the CHRA (center housing rotating assembly) spun more than it normally would have to create the 20+psi boost when testing the WG actuator. As exhaust flow increases, the more your turbo spins and creates boost (spool). To stop it from spinning and creating more positive charge air pressure on the intake, the wastegate opens up. That is the reason it is there. Without that the turbo would just keep spinning faster and faster, building more boost.

Most likely wrong direction to look in, but if a boost leak test shows a positive pressure leak then maybe it's not (positive pressure and vacuum leak test are two different things). As mentioned above, do a boost leak test. Most likely not the issue, but this is one of the first things that should be tested before spending money on parts.

[PsorianoPre99A4]

Meaning RPMs on the CHRA (center housing rotating assembly) spun more than it normally would have to create the 20+psi boost when testing the WG actuator. As exhaust flow increases, the more your turbo spins and creates boost (spool). To stop it from spinning and creating more positive charge air pressure on the intake, the wastegate opens up. That is the reason it is there. Without that the turbo would just keep spinning faster and faster, building more boost.

Most likely wrong direction to look in, but if a boost leak test shows a positive pressure leak then maybe it's not (positive pressure and vacuum leak test are two different things). As mentioned above, do a boost leak test. Most likely not the issue, but this is one of the first things that should be tested before spending money on parts.

Whats considered the proper way to do a boost leak test?

[Believer]

Whats considered the proper way to do a boost leak test?

It's probably easier for you to Google a DIY then type it all up here.

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[zandrew]

I really don't understand asking a question and when getting plausible paths to remedy not trying them. Why ask the question if you do not want to try the suggestions made? Have you tested the wastegate yet? If not why?

[PsorianoPre99A4]

I work and go to school during the week and don't have a chance to do anything until the weekend. I wanted to see if doing a throttle body adaptation with vagcom will work first, and I'll get my hands on one tomorrow. I'm definitely going to try what you suggested to test the wastegate first. I'll keep everyone posted.


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[PsorianoPre99A4]

Update:
So I tried to adapt the throttle body to group 060 and 098, both didn't work. I tried to put my stock ecu in to see if it would adapt to that and it didn't adapt either, and the car wouldn't even start (I think because bigger injectors and maf currently installed). Put the "tuned ecu" back in and cleared the codes and drove home codes didn't come back. However, on the way I home, I decided to go WOT, and I was hitting 20psi randomly pretty easily around 3800 rpms (this hadn't done this before since swapping ecus. It felt slightly faster, but not the 290 whp the tune claims. Could this be my stock fuel pump preventing it from pumping the 630cc? Also, could it possible that my throttle body is bad?
I don't know what's going on.. and now my boost at idle reads -16~, when it normally is around 19-20.

[xdewaynex]

Definitely need to do a boost leak test before you can move any further. The drop in vac reading at idle is a common sign of a leak.

[PsorianoPre99A4]

Definitely need to do a boost leak test before you can move any further. The drop in vac reading at idle is a common sign of a leak.

In the market for an air compressor now, but I don't think they're leaks. I realized it was only like that with my heater/ac fan on, but with that off, its right at 19-20.

[PsorianoPre99A4]

Update: A code hasn't come back, so I guess my throttle body adapted itself after clearing the code and unplugging the TB and ECU and plugging it back in while the door was open. Turned the key on "on" for 30 seconds or so, noticed the TB move. No codes and now I'm easily boosting up to about 22psi no problem. Really weird how that can be, I guess the TB was putting me in limp mode. However, I feel like I can be faster... I've been shifting at about 5krpms, it definitely feels like its much faster, especially when I'm high in boost. I feel like my stock pump isn't keeping up with the 630cc injectors. Or I guess this stage 3 tune isn't what I thought. I feel like my cousins stage 2 revo mk4 jetta can beat me :/

[Believer]

A data log of injector duty cycle and your air fuels will tell you if the pump is keeping up. Rev that thing out higher. The f21 will pull decently to 6.5k or more.

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