Hybrid turbo BXE>GT1749VC setup?

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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
Hello everyone,
recently I've modded my car with new hybrid turbo, into original BXE GT1646V case I've put GT1749VC rotors. Cold side housing is changed to GT1749VA. Obviously booth sides hot and cold had to be ported to fit rotors. ECU was tuned to this changes.
The turbo is lazy in low revs, over-boost in the middle and under-boost in high.
Log Log (0 - 008,010,011)
Current power is 173HP and 360Nm. All parts are original (except turbo and clutch).

My target is quicker response and more controllable turbo behavior.

Question:
- Can it be set by stop screw and/or accurator rod length? How?
 
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m1ketdi

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Seems like the stop screw needs setting up first. There used to be a good guide using an EMP and a boost gauge but it's gone now. Hopefully someone can help you. If not just trial and error it a little with 1/4 turns of the screw...

Do that and then re log.

To be honest the 100mbar over boost in the middle i wouldnt worry about.
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
EMP gauge will be hard to comply. I 'll try only with VCDS. Which values I should take care off during adjusting, actual boost only? When should I stop screwing in?
 
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m1ketdi

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It is most likely you will need to wind the screw out. Try turning back 1/2 a turn at a time and the relogging. If boost response improves try another 1/2 turn. Repeat until boost response does not change. Then screw in 1/4 turn the other way and re test see what it is like....
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
If I set the stop screw first to let's say 250mbar, then I will shorten the rod, would the rod setting increase the stop screw OFF pressure?
 
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faboka

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What the actuator test currently giving you now?

Isn't 250mbar on the high side? Stock turbos I've seen are around 130 to 150mbar.
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
I don't remember the HI LO figures but the difference is 90 mbar. I've found on the internet the correct range is 80-250 mbar, anything above or under is incorrect.
This is not a stock turbo (bigger rotors) and it is a bit lazy in low revs (see log) that's why I want to get close to HI limit.
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
I've done some adjustments, shorten rod (1,5 turn) and extend stop screw (2/3 turn, less lever travel)
Here is the VCDS VC Scope frame:

green-spec press.
yellow-actual press.
red-revs
white-duty cycle

and log
Log (0 - 011)

My concerns:
1 strange thing to me is the stop screw adj did not affect "charge pressure control" pressure (engine>basic settings>011), still 90 mbar, why?:confused:
2 how to avoid pressure drop (after spike)?
3 is it possible to wake up turbo earlier?

Please comment.
 
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m1ketdi

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Try lengthening actuator rod by 1 turn and try again... Turbo waking up earlier needs to be stop screw in the other direction...
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
m1ketdi said:
... Turbo waking up earlier needs to be stop screw in the other direction...
Click to expand...
That's what I told to the tuner, he said opposite, he said turbo was choking by exhaust gases!
 
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Tozi

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Anyone know how to fix pressure drop (after spike)?
 
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m1ketdi

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The pressure drop after the spike? If so thats called a poorly setup PID controller for the amount of overshoot you are seeing...
 
asap03

asap03

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Tozi said:
Hello everyone,
ECU was tuned to this changes.
The turbo is lazy in low revs, over-boost in the middle and under-boost in high.
Log Log (0 - 008,010,011)
Current power is 173HP and 360Nm. All parts are original (except turbo and clutch).
Click to expand...
Looking at group 008, you don't have 360Nm. In your case, smoke limitation gives the engine torque and it is 331.8 Nm. Do you have a log on 001 to see how much IQ do you have at WOT? I think that 2448 mbar requested boost is too much for your stock injectors.
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
Could only N75 map re-change help with turbo wake up?
 
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m1ketdi

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I think some smoke map changes would help the wake up more than the n75 map...
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
asap03 said:
Looking at group 008, you don't have 360Nm. In your case, smoke limitation gives the engine torque and it is 331.8 Nm. Do you have a log on 001 to see how much IQ do you have at WOT? I think that 2448 mbar requested boost is too much for your stock injectors.
Click to expand...
Log (1 - 001,003)
 
asap03

asap03

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Hi Tozi,

Thank you for the second log (groups 001, 003).

The log in the article is for Mk4, EDC15. That one starts with low N75 duty cycle and goes up for 80%. You have EDC16 ECU. In this ECU, N75 duty cycle starts high around 80% and decreases as rpm rises.

Regarding your log. IQ is at a max of 60 mg/str. This is the maximum for the stock PD 105 injectors. My mapping has around 58 mg/str, but I am running boost at just 2200 mbar. I don't smoke at all at WOT. So you can imagine that having 2448 mbar for the same 60 mg/str you go much leaner than me. I don't think you have enough energy in the exhaust gases to properly spool up that turbo at its capacity. You need bigger nozzles or ARL injectors to do more than 60 mg/str and then a good tune from Malone or other recognized tuner here. Then you won't have anymore turbo mapping issues.

This is my opinion, I'm no guru here, just my observations over time. I have the same engine as you.

All the best from Romania.
 
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Tozi

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Skoda Octavia 2010 1.9 BXE @177/397
I have to admit that my mechanic was right, the stop screw was too short. I realized that after some symptom that can be useful for others:

1 the turbo builder mentioned that while I was talking with him by phone (I told him about the over-boost while accelerating) ;-)
2 when you see my log high duty cycle is till 1554rpm (this mean something :) )
3 see the graph of pressure control valve test, there is a nipple at the end of ON stage



sometimes it can be seen on log right after ON stage (this means when vanes are opening give more efficiency)

4 and the organoleptic part :)
while pressure control valve test runs I put my palm and ear at the end of exhaust pipe and the engine breathe is clearly noticeable (gases and sound wave).

Tomorrow I will try to make it longer and let know.
 
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