Disconnected waste gate line from n75...

[AJacksA4]

Like the title states, I unplugged the vacuum line going to the actuator from the n75 and during WOT I max out at 20psi. The car wont overboost or anything like I was expecting. It holds 20psi all day. I also hear a loud raspy rattle under boost with the host disconnected.

Whats wrong here?

I'm trying to chase down a laggy boost issue and just trying different things out.

[walky_talky20]

Yeah...don't do that.

Your car (in an attempt to keep itself from a-sploding) is actually not giving you WOT. Your ECU sees that the boost has "gone rogue". It also sees that you won't knock it off with the freaking WOT runs. The moment things get unsafe it smoothly backs off the throttle plate to keep things in check. It could just do a hard fuel cut - like everybody else does - so you should be utterly amazed at how well it runs with zero wastegate control.

Welcome to the absolute end of the fuel and boost maps. You made it. And then you went further. <Slow Clap>

EDIT: You didn't mention that you were chipped. But if you were expecting more than 20psi, I suppose you must be. I guess I might expect maybe a little bit more boost before it started pulling throttle, in that case - but maybe not. Your rattle and raspy sound may be a loose wastegate or the gate being blown open by high exhaust pressure. You may be able to help it out by adding some more pre-load on the gate. I would start by measuring the pre-load with a pressure source. You can crank it up a bit so that it cracks at a higher pressure. I would recommend a crack pressure no higher than 5psi. Mine is at 5psi and its a little too high for correct smooth onset and control at the bottom end.

[AJacksA4]

Yeah...don't do that.

Your car (in an attempt to keep itself from a-sploding) is actually not giving you WOT. Your ECU sees that the boost has "gone rogue". It also sees that you won't knock it off with the freaking WOT runs. The moment things get unsafe it smoothly backs off the throttle plate to keep things in check. It could just do a hard fuel cut - like everybody else does - so you should be utterly amazed at how well it runs with zero wastegate control.

Welcome to the absolute end of the fuel and boost maps. You made it. And then you went further. <Slow Clap>

EDIT: You didn't mention that you were chipped. But if you were expecting more than 20psi, I suppose you must me. I guess I might expect maybe a little bit more boost before it started pulling throttle, in that case - but maybe not. Your rattle and raspy sound may be a loose wastegate or the gate being blown open by high exhaust pressure. You may be able to help it out by adding some more pre-load on the gate. I would start by measuring the pre-load with a pressure source. You can crank it up a bit so that it cracks at a higher pressure. I would recommend a crack pressure no higher than 5psi. Mine is at 5psi and its a little too high for correct smooth onset and control at the bottom end.

Lol funny enough I was just reading your thread about your boost issues a few years back. I'm basically having the same slow spooling issues... boost is slow to build but hits specified at ~3200rpm. I threw in a test pipe to rule out the cat (the cat material was in fact loose) but that didn't help the spooling issue.

Idk if you saw my other thread but these are my logs:



With N75



By disconnecting the waste gate line, I was seeing what sort of effect it would have. It held 20psi with the line disconnected, which is higher than when its connected.

I have a new (used) k03 sitting on my kitchen counter ready to go in, but I still want to get some more input on the issue. It seems like a new turbo solved your issue?

[ECS Tuning-Audi]

Has anyone actually posted any logs that show actual boost hitting the requested at low RPM (1840). Seems like it's almost impossible for the turbo to hit 10 psi at that rpm.

Jason

[walky_talky20]

New turbo and a tighter gate adjustment helped, yes. And sorry for coming off like an arrogant douchebag in my first reply. I was mostly just trying to be funny and identify the fairly dangerous nature of your testing method. I'm a pretty nice guy. Honest.

I should probably get around to doing some logs on mine and update that thread, eh? I can do some on my brother's ATW as well. His car always hit boost better than mine.

Your N75 duty looks pretty decent, but there is probably some room for improvement on the boost threshold.

[AJacksA4]

Has anyone actually posted any logs that show actual boost hitting the requested at low RPM (1840). Seems like it's almost impossible for the turbo to hit 10 psi at that rpm.

Jason

Yeah doesnt really seem possible lol. From talking to others I know the turbo should be spooled up by ~2500. Is that what your experience has been like?

[AJacksA4]

New turbo and a tighter gate adjustment helped, yes. And sorry for coming off like an arrogant douchebag in my first reply. I was mostly just trying to be funny and identify the fairly dangerous nature of your testing method. I'm a pretty nice guy. Honest.

I should probably get around to doing some logs on mine and update that thread, eh? I can do some on my brother's ATW as well. His car always hit boost better than mine.

Your N75 duty looks pretty decent, but there is probably some room for improvement on the boost threshold.

Haha no worries man, I knew from the get go that it wasn't a smart thing to do. Yeah I'm leaning towards throwing in the new turbo as a last effort, may change the exhaust manifold gasket while I have everything apart down there. I don't hear anything as far as leaks but being such a cheap part, its worth a shot.

[ECS Tuning-Audi]

Yeah doesnt really seem possible lol. From talking to others I know the turbo should be spooled up by ~2500. Is that what your experience has been like?

I would say by 2800-3100 I have full boost. The current turbo/cat on my B6 has 219K on it so they're definitely on their last legs. I'm actually swapping out everything this weekend. I have a brand new K04 and 3in testpipe ready to go in. The old turbo had a bunch of in and out shaft play so it was definitely shot. I'm surprised it has lasted this long.

I'm hoping for a noticeable difference in how the car responds with a brand new turbo and no restriction.

Jason

[walky_talky20]

Looks like I did log my brother's car. Meets 17-18psi request by 2700 RPM or so. N75 duty at about 75% to do it.

[2stroke]

I would recommend a crack pressure no higher than 5 psi.
Mine is at 5 psi and its a little too high for correct smooth onset and control at the bottom end.

Wastegate actuator cranking opening pressure ?

1.8T 20V longitudinally mounted motor. ( Audi A6 / Audi A4 / VW Passat / Skoda Superb / Seat Exeo )

What is considered as normal wastegate actuator cracking opening pressure for these Turbo's ?

* K03-005
* K03-029
* K03-073
* K04-015

[walky_talky20]

Stock adjustment is not very tight. From experience: on an unaltered OEM turbo, the wastegate disk can spin with around 2-3 psi applied to the actuator. This equates to about "1 turn of the nut" worth of pre-load on the actuator or less. I'm not aware that there is any variance of this adjustment between any of the factory turbos.

Maybe somebody else will chime in with more official informations.

[2stroke]

Stock adjustment is not very tight.
From experience: on an unaltered OEM turbo, the wastegate disk can spin with around 2~3 psi applied to the actuator.
I'm not aware that there is any variance of this adjustment between any of the factory turbos.

Found information about one of the above Turbo's.....

Acording to technical specifications from BorgWarner the factory setting cracking pressure for K03-029 should be -----> 0,37 Bar / 5.366 psi

[walky_talky20]

I wonder if that might be the "fully open" value or something?

I haven't seen any OEM K03 turbo with a measurable "crack pressure" of 5psi. I adjusted mine to be exactly that and it took quite a few extra "turns of the nut" to get it there. Unplugging the N75 on a 1.8T will generally give you much less than 5psi. Usually 2 or 3 psi is expected.

[2stroke]

I wonder if that might be the "fully open" value or something ?
I haven't seen any OEM K03 turbo with a measurable "crack pressure" of 5 psi.
I adjusted mine to be exactly that and it took quite a few extra "turns of the nut" to get it there.
Unplugging the N75 on a 1.8T will generally give you much less than 5 psi.
Usually 2 or 3 psi is expected.

I have 2 pieces of K03-029 ( for 1.8T engine ) lying on the bench and I want to check if the actuator and wastegate works as it should and if it opens as it should, etc.

At what pressure should the wastegate plate be 100% completely open ?
Should the arm always be connected to the wastegate when checking etc ?
Anyone who can contribute with some instructions how to measure and so on ?

[Cybersombosis]

I use a leak down tester set to 4-5 psi. I found that my compressor’s regulator isn’t sensitive enough. I put a mark on the rod so it’s easier to see it move. 1psi is way too soft. You will get boost creep. Cracking pressure is what we are testing for. Your crack pressure is currently 1psi. As long as you are setting crack pressure to 4-5 psi, you don’t have to worry about the wide open pressure.

[Jayz691]

Crack pressure should be 5-6psi..
Too low wont give ya "boost creap", it'll make it hard to hit your target boost.

Sent from my LM-V600 using Audizine Forum mobile app

[Cybersombosis]

Oops sorry I used the wrong term. If the spring pressure is too low (1PSI was mentioned), the force of the exhaust gasses can push open the wastegate and not allow you to build boost properly.

[2stroke]

I put a mark on the rod so it’s easier to see it move.
1 psi is way too soft.
...If the spring pressure is too low (1 psi was mentioned), the force of the exhaust gasses can push open the wastegate and not allow you to build boost properly.
Cracking pressure is what we are testing for.
Your crack pressure is currently 1 psi.
As long as you are setting crack pressure to 4~5 psi, you don’t have to worry about the wide open pressure.

Crack pressure should be 5~6 psi
...Otherwise it'll make it hard to hit your target boost.

1. So just when the actuator arm starts to move is what is called 'Cracking pressure'.

2. Should this be tested with or without the actuator arm connected to the wastegate ?

3. Since 5-years back my engine has Stage-1 modified software, but of course I want to make it work as well as possible.

- - - - - - - - - - - - - - - - - -

I just found this on FORGE homepage for 1.8T ( 20 v. ) engines:

4. Is the table below something to be concerned about in this context ?
5. Is there something in the table that I should make use of ?
6. They use different terminology but what pressures are they referring to ?

Diaphragm Actuator spring pressure set up:

* Running pressure 10 psi (0.7 bar) - spool up/opening pressure 5 psi (0.35 bar)
* Running pressure 13 psi (0.9 bar) - spool up/opening pressure 7 psi (0.5 bar)
* Running pressure 15 psi (1.0 bar) - spool up/running pressure 9 psi (0.6 bar)
* Running pressure 18 psi (1.2 bar) - spool up/running pressure 14 psi (0.95 bar)
* Running pressure 20 psi (1.4 bar) - spool up/running pressure 17 psi (1.1 bar)




This is the Stage-1 software from BHP-Motorsport in Germany that I have in my car.

What I have in my CPU .jpg

[Cybersombosis]

1. It’s cracking pressure not cranking pressure. To open up a crack.

2. Everything needs to be attached and a preload applied to the actuator.

As stated, 5 psi is the sweet spot on a stock turbo. Don’t make it more complicated than it has to be.

[2stroke]

1. It’s cracking pressure not cranking pressure. To open up a crack.

2. Everything needs to be attached and a preload applied to the actuator.

3. As stated, 5 psi is the sweet spot on a stock turbo. Don’t make it more complicated than it has to be.

1. ...sorry, English is not my spoken language.

2. Good to know.

3. Since it seems that the actuator springs in both of my actuators are not even close to the correct pressure, I wonder if it is better to look for a new actuator ?


The table below is an example for VAG cars with transverse 1.8T engine:

All the following KKK / BorgWarner K03- turbos have the same installation dimensions and thermodynamical performance.
The differences are only in the actuator that opens the turbine bypass valve:
K03-011 ----> 65 N actuator
K03-026 ----> 85 N actuator
K03-035 ----> 85 N actuator
K03-044 ----> 65 N actuator
K03-045 ----> 85 N actuator
K03-049 ----> 65 N actuator
K03-052 ----> 85 N actuator
K03-053 ----> 85 N actuator
K03-058 ----> 85 N actuator

The 1.8T ( 20 v. ) versions with higher output have an actuator with a higher opening force due to the higher exhaust gas pressure
( which is a consequence of the higher boost pressure ).
Otherwise the valve would be pushed open by the exhaust gas pressure.

Additionally, with re-mapping of the ECU you can achieve about 215 hp with the newer K03's without danger of overspeeding the turbo.
With the older K03's turbos, 195 hp is the limit.

Best regards // BorgWarner Turbo Systems AG Germany.

...It would be interesting to know similar facts for the models with longitudinally mounted 1.8T engine !?!?

[2stroke]

I have now tested both of mine K03-29 Turbo's and both of them had a cracking pressure of ~0,2 Bar / ~2.9 psi
( both with connected wastegate flapper. )

According to technical specifications from BorgWarner the factory setting cracking pressure for K03-029 should be -----> 0,37 Bar / 5.366 psi

Is it ok to just adjust the nuts on the actuator rod until it reaches 0,37 Bar / 5.366 psi ?


From the testing:

Stroke length of the actuator arm: (measured from the time it starts to move until it does not move any more)
~16 mm. / ~0.629 in.

Cracking pressure:
~0.20 Bar / ~2.9 psi.

Maximum open pressure:
Old: ~0.6 Bar. / ~8.7 psi.



But if I adjust the position of the nuts on the actuator arm, so does the total range of motion for the actuator arm also change !?!?
and it's not good, or is it ok ?


.

[grayjay]

Shortening the actuator arm to restore pre-load tension should not change the range of motion, it will just occur at different range of pressure within the canister. Travel length of the diaphragm in the canister is unchanged. In any case, I think the ECU should still have good control of the actual delivered boost by cycling the N75 valve open/closed. The N75 is cycled via a PID control loop in response to measured changes of the boost pressure sensor so can accommodate for some variation of the canisters actual crack pressure and max opening pressure. In other words, it does not depend on a 50% N75 duty cycle to achieve a specific boost pressure, instead it variably cycles the N75 in response to the measured boost level. It would just become problematic if the turbine housing pressure were able force the wastegate open without any control pressure in the canister (N75 closed).