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Author Topic: High base pressure and overboost  (Read 3012 times)
olobolo1996
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« on: April 26, 2020, 03:03:56 PM »

Hi. Here is my problem:
When cruising at around 3000RPM at 6th gear with just a little throttle, my actual pressure is around 1400-1500mbar absolute, while requested is around 900mbar.
How do you fix this? I dont want to raise KFMIRL in this area, because it will cause the throttle to open further and thus to accelerate.
I tried changing maps associated with plgru but it does not help
Should I mess around with KFWDKMSNVP to cause pressure drop over throttle valve?
Below logs:



Link (click on the second tab):
https://log.tunezilla.com/s/nmQKllaQ
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BlackT
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« Reply #1 on: April 26, 2020, 03:32:16 PM »

Looks to me like hardware problem, your WGDC is 0% and boost is rising even throotle plate is open 20%
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fknbrkn
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mk4 1.8T AUM


« Reply #2 on: April 26, 2020, 03:33:43 PM »

Whats the problem? It's an actuator spring pressure
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olobolo1996
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« Reply #3 on: April 27, 2020, 10:42:43 AM »

The spring characteristics is eqeual to OEM. I have even tried to extend the actuator shaft, so the wastegate flap is a little bit loose. It just cased massive lag, and dropped 0.1 or 0.2 bar, but I dont think it is the right way. I will try disconnecting hose from N75. If it helps it might indicate faulty valve. Anyway The turbo is K03 hybrid.
BUT
What if the turbo spools up so ridiculously easy- has someone tried controling the base boost with throttle valve? In FUEDK section MED9.1 FR there is something about it. I tried different ways there but with no luck.
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prj
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« Reply #4 on: April 27, 2020, 01:55:16 PM »

You are trying to solve a problem that does not exist. You also posted 3 threads now about it I think?
Or rather that is inherent with all cars where the actuator is not a vacuum type actuator.

IRL/IOP have absolutely nothing to do with it.
FUEDK has absolutely nothing to do with it.

The ECU as well as the engine has two regions of operation:
a) Throttle
b) Unthrottled

In Throttled operation the N75 is fixed to 0% and filling is controlled through throttle valve, like a NA engine. It is totally normal if pvdk > plsol. This is pressure pre-throttle, not in manifold. On a NA engine it's exactly the same - you have pu_w as base pressure and your target pressure (ps_w) is lower, so throttle is used to limit it. On turbocharged car you just have pvdk_w instead of pu_w, the idea is the same.
In Unthrottled operation the throttle is WOT and the filling is controlled through the N75 valve.

Really this post should be moved to "noob" section, because you are trying to run before you even learned to walk.
1. Learn to use ME7Logger and post logs.
2. Learn the basics of how a turbocharged engine with e-throttle works.
3. Read and re-read the wiki.

You skipped all these 3 points and are trying to change maps randomly that you have no idea what they do.
You will never EVER get anywhere like this, even on an ECU that is over 20 years old. You need to understand the basics of how it works to make meaningful changes.

If you even have any issues with control (which you won't know until you make proper logs), then that can be solved by changing the maps that define the boundary between throttled and unthrottled mode.

EDIT:
I actually see that this is a MED9 ECU. Well in this case, try to tackle this on a ME7 first. MED9 works exactly the same way re throttle control.
But you will never ever find out whether your changes are making a difference or whether there is even a problem without good logs.
« Last Edit: April 27, 2020, 02:00:44 PM by prj » Logged

PM's will not be answered, so don't even try.
Log your car properly.
olobolo1996
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« Reply #5 on: April 27, 2020, 03:15:02 PM »

Thank you for the reply prj. I know that this is my 3rd thread about this, but I still do not get it.
If you say that this is a normal when actual pressure is bigger than requested pressure, then why am I getting overboost fault near 3000 RPM?
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fknbrkn
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mk4 1.8T AUM


« Reply #6 on: April 27, 2020, 04:07:41 PM »

What is the base spring pressure?
If you see actual pressure higher than that (and boost curve doesn't respond to n75 dc changes) then it's probably a damaged wg actuator lines

If it's just a tighter wg, read wiki about that
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