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Discussion Starter #1
Hi guys,

I have been fighting this for a while but now I feel compelled to try and really get it nutted out, the lack of lower-midrange torque is starting to frustrate.

Anyway, the short of it is that my internally gated GT3076R (yeah yeah I know...) opens starts to open wastegate before it reaches the desired boost level - which induces a reasonable amount of lag any time I step on the throttle. Here is the best way I can demonstrate how it behaves when I am targetting 15psi:


Obviously I would much prefer it to hit and hold 15psi instead of pissing around from 11psi to 15psi. I have tried an AVC-R and a bleed valve as different kinds of boost control which help SLIGHTLY but definitely don't fix it, and I am currently trialling a dual-port actuator which so far does the exact same thing. Today I decided that to rule out the possibility that the reason it spools lazily is a boost leak or some other issue elsewhere, I'd do a quick run to 3500rpm with the actuator hose removed to see how much it builds and my result is:


So clearly the turbo and setup is capable of building 1+bar well before the 5000ish rpm I am stuck with at the moment, but the trick is making it do so without free boosting. Any one have any ideas? It may help reduce some stress here :D

Cheers!
 

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Is the AVC-r solonoid plumbed in correctly? what base boost are the wastegates set to open at ie boost levels with boost controller off
 

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Discussion Starter #4 (Edited)
I am pretty sure the AVC-R is plumbed in correctly, it at least was with the single port actuator as otherwise I would have expected it to have no effect on spool. I have played around with different adjustments, running 23% duty across the board resulted in a curve similar to the one posted.

I played with setting rpm specific duty, doing 90% up to 3500rpm then lower above that to avoid spiking which helped a bit but the problem is I couldn't get aggressive enough on it to have it pull straight to full boost as obviously spool isn't just rpm related, so settings which were suited to if I floored it at 3000rpm and let it pull through could result in it not reaching full boost if I floored it at 4500rpm. Ones suited for if I floor it at 4500rpm could result in it over shooting the mark if I floored it earlier, if that makes sense?

The single port actuator ran around 12-13psi with no extra boost control - the dual port seems keen on around 10psi. So far I haven't been able to ascertain ANY difference from having the AVC-R on or off, I have tried playing with different settings and it appears to do nothing yet from what I can tell everything is plumbed in correctly as per the AVC-R setup instructions for a dual port (/ external) wastegate.

Is there any setting on the AVC-R I need to change for an "external" style wastegate setup? Off the top of my head what I have done is changed from plumbing the boost feed into COM, and then from NO to the single port actuator - to putting the dual port one in and T-ing the boost feed, putting one feed into the "boost" port on the actuator and feeding the other side to COM on the solenoid and then plumbing "NC" to the boost controller port on the actuator. Does that make sense, or does it sound correct?>

Cheers :)
 

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After reading your posts, I was wondering where you are taking the pressure tap for the AVCR from?
 

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First, use a vacuum / pressure pistol (hand pump) connect it to the wg and see at what pressure the wg starts to move.

If it starts to move at very low pressure, then you can try to shim the wg bracket a little to make it open at a higher pressure. Or make the rod shorter if it is adjustable.

Secondly, i would loose the electronic controller. Put in a manuel controller. I use a Turbo XS wich preloads a spring / ball, this keep the boostfeed to the wg closed until you reach desired boost, then fine adjust with the bleed portion on the valve.

It is also very important to use the boostfeed to wg from a pressurepipe only, not from the intake / vacuum side.

 

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Discussion Starter #7 (Edited)
Cheers Asim :) The manual ones tend to be a bit inconsistant in different conditions, don't they? I had however been considering doing what you describe - after my experiments I have a strong suspicion the ball valve setup would work better than what the AVC-R is doing for me. The boost feed I am using for the actuator etc is from the crossover pipe between the BOV and the throttle body - this is a single GT3076R on an RB25DET by the way.

Both wastegates I have used have adjustable preload, the single entry one I kept winding up preload and I reached a point where it stopped spooling any harder and in the end just started boost creeping while still opening at around 12psi :( Admittedly I haven't wound the new actuator's preload right up, probably about 75% of the way though and I stopped when the gains started seeming pretty unexistant. I'll try winding it the whole way and see if that helps!
 

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Cheers Asim :) The manual ones tend to be a bit inconsistant in different conditions, don't they? I had however been considering doing what you describe - after my experiments I have a strong suspicion the ball valve setup would work better than what the AVC-R is doing for me.

The boost feed I am using for the actuator etc is from the crossover pipe between the BOV and the throttle body - this is a single GT3076R on an RB25DET by the way :)
Mine works flawlessly (is that a word?) in all weather, even in the crappy weather we have in Norway :p

Ahh... BOV valve. The source of many headaches!
Did you try to remove the bov?
I have experienced lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots of bov leaking, and making boost come on late. :banned:

Asim
 

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the avcr is a nice piece of equipment but its a bitch and a half to run properly.

one thing i know for sure is that it was reported doing exactly what you're describing with some wastegates/actuators, if the self learn mode is activated.

i'm no expert but i'd look into having it manually tuned, or try to learn to do so yourself, theres a lot of info on the net.
 

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Discussion Starter #10
Ahh... BOV valve. The source of many headaches!
Did you try to remove the bov?
The reason I pulled the actuator hose off the actuator and "free boosted" up to 3500rpm was to eliminate boost leaks due to various reasons - including BOV, and getting 1.1bar by 3500rpm implies to me all that is working fine. Or do you mean removing the BOV for another reason? Do you think it could mess with the boost signal to the wastegate somehow?


I have experienced lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots and lots of bov leaking, and making boost come on late. :banned:
Yeah me too, but to do with split lines to the BOV or general BOV malfunction causing it to release boost under load - the BOV seems to be fine going by the test I mentioned above :)


Sourell:

I know how to use the AVC-R, I have played with manually tuning it - as per my comments above about setting it to 90% duty from 3000-3500rpm but having issues with finding a balance at higher revs and ending up having to live with the described issue :(
 
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