NefMoto

I've recently completed a rebuild of a 1.8T with a number of upgraded goodies including a built bottom end and a new turbo kit (PPT).  I'm beginning to move on from fueling on this Stage 3 tune and I'm run into a bit of a snag while tuning and setting up boost control.  I'm unsure at this point if my problem has to do with tuning or hardware but let me explain.

I've used the following boost line configuration for the Tial wastegate which seems to be pretty standard:
(http://i.imgur.com/cLGO9.jpg)

My issue is that I do not have any boost control whatsoever.  The boost skyrockets past 30PSI immediately regardless of what I've tried, other than just running directly off of wastegate pressure which is about 14.5 PSI.  In any other configuration, there seems to be zero control.

-I've tried setting KFLDRL to 0 across the board (as a control test). I expected this would effectively be the same as running off of wastegate pressure.  No effect.  However, since the positive pressure is constant (or should be) at the bottom of the wastegate valve, shouldn't I be inverting KFLDRL to run a high duty cycle (bleeding off 95% of boost)?

-So I tried setting KFLDRL to 95.0 across the board.  Again, no effect.  Surely one of these two configurations should have *some* effect on boost control.  But no.  Zero, zilch.

-Then I tried placing a MBC in place of the N75, turned all the way down.  This should allow no flow to the top of the wastegate valve.  Again, no effect.

I assume it's safe to say that my problem is hardware related somehow?  But how?  The wastegate operates normally at 14PSI until it's connected to something on the top of the valve.

I have logs, but they're generally useless.  They just show what I've said above.  Any ideas?

I'm pretty sure you need to either keep the bottom port at ambient, or somehow limit the amount of boost the lower port sees (compared to the top port), or the WG will never open.

If you keep it at ambient, you may not spool as fast or hold as much boost pressure.

Hooked up wrong, only use one port, third n75 line also goes to ambient for the bleed.

I just use bottom port.  Top is open.

Thanks for the tips guys. I just did a once over of all the lines again and found that the clamp on the bottom port of the wastegate was loose and was leaking.   ::)

I was wondering if people just run the N75 on the bottom port and this answers my question. It doesn't seem like I have much control using the top port.

I always did it like this:

http://forums.audiworld.com/showthread.php?t=1476692

This.

thread bump, did the first post diagram work after securing the clamp?

the top diagram is how you do it with some controllers, not the n75

with the n75 when it cycles it would effectively lock the top port and never allow the diaphragm to work

My understanding of it with the above diagram the N75 is connected to the top port, bottom port has a positive pressure source as well hence the T piece in the line. The n75 still receives boost pressure and sends thru to the top port of the WG, once boost levels are acheived the N75 will bleed of pressure into atmos/intake out the 3rd nipple (longest one) making bottom port pressure > top port pressure and then opening wastegate ???

Just use bottom port only and job done.

If I use bottom port only my car overshoots target by about 200mbar once full boost is achieved.

Then retune boost control....

Will be doing so matchew, going over s4wiki again, will change the Boost PID I  :)

Just wanted to know if there was another successful way of using the N75 on the top port of WG.

Cheers

Mine runs on the top port and works just fine. 

Same as the reference picture in first post?

I use twin MVS Tial gates on the RS6 with twin GTX3071s and I'm using the n75 tee'd to both bottom ports on the Tial wastegates, works perfectly.

oh...sounds interesting...  I would like to see your KFLDIMX and KFLDRL maps if its possibe ;-)

Tuning is currently a work in progress we are currently getting the 1000cc injectors sorted (850cc @ 3 bar but running them at 4 bar).

I have help from someone on this forum and can't give anything out without his say so.  What I can do is point you in his direction if you like.

Here is the link to the nefmoto build thread only a couple of pics but there is a link to my full build thread.  http://nefariousmotorsports.com/forum/index.php?topic=2486.0title= (http://nefariousmotorsports.com/forum/index.php?topic=2486.0title=)

I was originally worried that the n75 could not control the Tial gates but seems to work very well.

I also use stock n75 on external tial
works fine

I don't know how the N75 ports work because I'm new to this type of ECu's. But if it opens ports 1 & 2 when energized then if you put it to the top of the wastegate you will have max boost at 100% duty only when the exhaust pressure is enough to overcome the spring pressure by itself. This is usually a little more than twice the spring pressure. So if you have a 10psi spring you will get about 24psi at 100% duty.

If you connect it only to the bottom you will have 10psi at 100% duty and more boost at less duty cycle.

Unless the solenoid output is inversed.

Could someone perhaps post a picture of their actual Top port setup?

Everything is opposite of what you just said.

No it's not. If it is "working" opposite it means the valve's duty cycle is reversed or the port configuration is different. I know the valve in the picture but I don't know the N75.

My comment was made about the N75.

100% duty = shut gate. The N75 either routes the pressure coming into the bottom port through a restrictor out of the short port or it routes it to all ports.
When it is on, it routes it to all ports, thus the pressure is fed back into the intake, and the wastegate chamber sees no boost, allowing the boost to rise.
When it is off, the long port is blocked, and all boost gets fed into the bottom chamber of the wastegate, opening the gate.

WTF?

My setup:
Line from intake manifold or turbocharger to bottom port of n75, short port on the sideof the n75 goes to the top port of the Tial.  Long port left open.

And bottom port has no positive pressure attached to it, or does it have manifold pressure as well?

Top port of the tial? I am guessing you mean the bottom port.
As if it was going to the top port, you'd be pushing on the membrane and shutting the wastegate the more duty is increased.

This would not work.

For those wondering what I did a few months ago after receiving feedback in this thread.  I took the advice of many and left the top port open, and allowed the N75 to manipulate only the bottom port.  This is a much simpler configuration and allowed better control of the wastegate from what I found.  I did need to heavily modify KFLDRL and KFMLDMX (basically had to tone them down).  Eventually I'd like to perfect the PID so part throttle boost delivery is cleaner, but it works for now.

You are right.  It is going to the bottom prt.  Top port on Tial is left open.