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Author Topic: Questions about symptoms...  (Read 53662 times)
nyet
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« Reply #30 on: May 24, 2013, 09:24:07 AM »


I hope I don't have this backwards but if the WGDC is at 75% the actual waste gate valve should be open roughly 3/4 of the way?

No. First, you have it backwards. The higher the WGDC, the more the WG is held closed.

Second, the "amount open" has as much to do with manifold pressure as WGDC...

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I'm still breaking in the clutch but I get mad overboost with barely any throttle. I mean needle bouncing off the 25psi mark on the boost gauge and it only goes to 25psi...kinda overboost at 2700+rpm. I don't have any logs yet as I am breaking in the clutch and dialing some ev14 550's using 2.7bar on an ECS tuning adjustable FPR and Geneses fuel pump by looking at the ST & LT fuel trims. Just been looking at them live after like 20miles of driving with VCDSPro.

You shouldn't have done any real driving w/o at least doing a little bit of WG tuning.
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shane0569
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« Reply #31 on: May 24, 2013, 10:49:38 AM »

Okay, I've done a little more investigating and actually opened up the N75. It does not operate as previously explained. When the valve is not energized, it routes ALL boost pressure into the Wastegate actuators causing them to fully open. When the valve is energized, it opens a plunger inside that allows air to pass into the PCV spider hose system AND into the Wastegate actuators simultaneously. So, when testing...when the valve is energized and you blow into the bottom port, you will find that air is normally allowed to come out both other ports if the valve is good.

So, after I found that, (no real problems with the N75), I went and disconnected the tube to the Wastegate actuators completely, and cautiously did a short run to verify that boost would be there if Wastegates remained fully closed, and sure enough it was building much more boost, much more quickly. So, this doesn't make any sense.

What I'm thinking now is either the PCV valve is not working correctly and not properly venting the extra pressure from the crankcase and N75, or for some reason the crankcase pressure is too overbearing and when the N75 opens "to atmosphere", it can't properly went the extra boost because of pressure equalization.

So, I guess my next test will be to run it without the long port on the N75 connected.
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nyet
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« Reply #32 on: May 24, 2013, 10:51:47 AM »

So, when testing...when the valve is energized and you blow into the bottom port, you will find that air is normally allowed to come out both other ports if the valve is good

Yep, this is why I said to cap the long port Smiley

BTW it has to open this way to relieve any pressure built up in the wg lines...
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shane0569
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« Reply #33 on: May 24, 2013, 12:39:54 PM »

Yes, if you cap the long port, and energize it, air will still be allowed to come out the wastegate control port....
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shane0569
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« Reply #34 on: May 24, 2013, 12:52:09 PM »

Anyway...if I end up having to change the PID tuning...would I begin by increasing KFLDIMX in the 850 and 1000 columns?

And, say I am running at approx 95% WGDC in the current tune. Is that referring to 95% of the physical capabilities of the valve, or 95% of the max duty cycle for this tune?

In other words, would changes to KFLDIMX accomplish anything if it is at 95% currently?

Thank-you
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phila_dot
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« Reply #35 on: May 24, 2013, 02:25:08 PM »

95% WGDC is N75 fully open, ECU requesting max boost

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shane0569
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« Reply #36 on: May 24, 2013, 02:33:51 PM »

95% WGDC is N75 fully open, ECU requesting max boost



Ok, that's what is was thinking...if I disconnect the lines to the WG from N75, it will boost...what could be causing this then?
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phila_dot
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« Reply #37 on: May 24, 2013, 04:11:38 PM »

Disconnecting the lines from the N75 to the WG should cause uncontrollable overboost well in excess of the MAP.

What does "it will boost mean"?
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shane0569
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« Reply #38 on: May 24, 2013, 05:03:28 PM »

Disconnecting the lines from the N75 to the WG should cause uncontrollable overboost well in excess of the MAP.

What does "it will boost mean"?

It means I only got on it for about between 3500 and 4500 while logging once to see if I had a turbo or waste problem.

It built boost right up to 22 psi no problem, so I got what I was looking for. So, it's obviously not a massive boost leak.
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nyet
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« Reply #39 on: May 24, 2013, 05:20:59 PM »

Yes, if you cap the long port, and energize it, air will still be allowed to come out the wastegate control port....

No, it should not.
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nyet
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« Reply #40 on: May 24, 2013, 05:22:40 PM »

Is that referring to 95% of the physical capabilities of the valve, or 95% of the max duty cycle for this tune?

The N75 is a solenoid. 100% DC would burn it out. 95% means all manifold pressure is being diverted away from the wastegate, and is equivalent to disconnecting the wg line from the n75.

If you get different results (between 95% and wg line disconnected), your N75 is bad (or harness is bad).
« Last Edit: May 24, 2013, 05:24:25 PM by nyet » Logged

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userpike
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« Reply #41 on: May 24, 2013, 05:31:50 PM »

No. First, you have it backwards. The higher the WGDC, the more the WG is held closed.

Second, the "amount open" has as much to do with manifold pressure as WGDC...

You shouldn't have done any real driving w/o at least doing a little bit of WG tuning.


Thank you for clarifying.
 As far as WG tuning, I pretty much combined elrey's kfldrl map to the first 3 columns of a stock Audi TT 225 kfldrl. and ran with it. But since ddilenger said that on the previous page about the heavier spring in the WG requiring the PID to be recalibrated then I guess it doesn't matter. It's just gonna overboost no matter what I guess. Maybe I'll run the map with like 30% DC across the board and see what happens before I delve into stuff I'm not too sure about yet(completely recalibrating the boost PID). Plus I'm still breaking in a clutch so I shouldn't be driving it hard anyway right now.
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shane0569
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« Reply #42 on: May 24, 2013, 06:13:53 PM »

No, it should not.

Yes it will. Have you disassembled one?
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shane0569
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« Reply #43 on: May 24, 2013, 06:45:52 PM »

Here is a diagram of exactly how the valve section of the N75 works.

The plunger is held down by default by a small spring. When the solenoid is energized it pulls up and away from the tube that supplies the manifold pressure. As you can see, there is a direct link between the input and output to wastegates at all times. When you energize, it merely gives that pressure another route to travel.
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nyet
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« Reply #44 on: May 24, 2013, 06:59:19 PM »

Err. Sorry. You are correct. I assumed that only wg pressure could escape back into the intake/PCV. I was assuming you dont want manifold pressure to leak that way, but I guess it does.
« Last Edit: May 24, 2013, 07:04:05 PM by nyet » Logged

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Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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