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Thread: VGT Tables for E98

  1. #11
    Lifetime Member Tre-Cool's Avatar
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    you got the first one right, 0% partly right. with the vanes at 0% your fully open allowing the most exhaust air to bypass spinning the turbo turbine. so your turbine/compressor wheel speeds should slow down.

    what you then need to take into consideration is any piping/intercooler restriction from the turbo to the intake. if the pipes can only flow so much air then you could be seeing 35psi on the outlet of the turbo, but seeing 27psi into the motor.

  2. #12
    Senior Member SV8346's Avatar
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    But if that was the case of producing for example 35psi at the turbo and only 27psi at the engine, wouldnt the ecu be asking for more boost since its programmed to give it nearly 40psi. When i watch the logs, the boost builds up near instantly with the vane opening but as soon as the vane gets to 40% it stops opening any further and holds solid at 40% yet at the exact same time the engine starts to now consume more than what the turbo can produce. Just seems a little coincidental that as soon as the turbo vane hits the limit of 40% the turbo can no longer produce enough air to maintain a solid boost so even though i am commanding 40psi the turbo is still 40% from being fully opened.

    Well ok, i sort of get get what your saying now but would still definitely be nice to be able to adjust it and play around with it and learn more about it first hand, i have read numerous articles and forum posts from members getting much better results by fine tuning the VGT using hpt. Guessing by the looks of it the only way thats going to happen is i'll need to buy hpt instead.

    As a few of us have seen, the piping and intercooler on the RG's are definitely not a restriction. There is a tuner in QLD still running the factory piping and cooler with 315hp and 900nm of torque at the wheels from the E98.
    2016 RG Colorado 2.8TD

  3. #13
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    SV8346, I don't know if this helps you or not, and I have the 2012 RG with the Bosch EDC16C39 ecu, but they still run the same turbo.

    I have left the vane position tables stock but I am able to demand whatever boost I like and it follows it beautifully. The Bosch ecu has about 5 tables from memory. Desired boost table and then about 4 different limiters based on Baro, RPM etc, etc.

    I played with vane position entering some silly values just to see what result I got, but it made no difference. From real world daily driving and data logging, the stock tune with approx 23psi boost passed about 180 g/s of air past the maf at 3000rpm. At 28psi, I see approx 215 g/s. At 30psi I see 220 g/s. At 35 psi I see 225 g/s. This is with stock inlet. Seems to me that with the stock inlet track and its sharp short turn radius entry into the front of the turbo, these turbo's flow really well up to about 28 psi, but there are diminishing returns after that. I run a 30 psi tune as my daily driver which netted me 222 rwhp (stock 140). Not a tow tune by any means as its pretty aggressive and smokey at high rpm but great as a my daily transport with heaps of low-mid range torque, its awesome.

    I know my vehicle is from an earlier year and runs a different ECU, but I just thought it may assist with your diagnosis.

    Cheers.

    Craig

  4. #14
    Senior Member SV8346's Avatar
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    Quote Originally Posted by OzDuramax View Post
    SV8346, I don't know if this helps you or not, and I have the 2012 RG with the Bosch EDC16C39 ecu, but they still run the same turbo.

    I have left the vane position tables stock but I am able to demand whatever boost I like and it follows it beautifully. The Bosch ecu has about 5 tables from memory. Desired boost table and then about 4 different limiters based on Baro, RPM etc, etc.

    I played with vane position entering some silly values just to see what result I got, but it made no difference. From real world daily driving and data logging, the stock tune with approx 23psi boost passed about 180 g/s of air past the maf at 3000rpm. At 28psi, I see approx 215 g/s. At 30psi I see 220 g/s. At 35 psi I see 225 g/s. This is with stock inlet. Seems to me that with the stock inlet track and its sharp short turn radius entry into the front of the turbo, these turbo's flow really well up to about 28 psi, but there are diminishing returns after that. I run a 30 psi tune as my daily driver which netted me 222 rwhp (stock 140). Not a tow tune by any means as its pretty aggressive and smokey at high rpm but great as a my daily transport with heaps of low-mid range torque, its awesome.

    I know my vehicle is from an earlier year and runs a different ECU, but I just thought it may assist with your diagnosis.

    Cheers.

    Craig
    Yeah it is quite possibly maxing out the inlet and outlet capabilities of the turbo. Another thing you have mentioned that seams interesting is the MAF readings. Could the older MAF's be different to the newer MAF's? When i do different boost logs i get the following MAX MAF readings, 28psi - MAF 208G/s, 30psi = 208G/s, 32psi = 208G/s, 37psi 208G/s. Seams to be that at just about any boost above 28psi and approx 2400rpm the MAF reaches its max reading? I'd only be guessing that the engine would be consuming more air at 3500rpm as opposed to 2400rpm yet the MAF is still showing the same G/s reading? Can the MAF be recalibrated or adjusted? I have seen the maf frequency tables but not game enough to touch those?
    2016 RG Colorado 2.8TD

  5. #15
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    Quote Originally Posted by SV8346 View Post
    Can the MAF be recalibrated or adjusted? I have seen the maf frequency tables but not game enough to touch those?
    As you have already mentioned, your actual airflow past the maf will be increasing with rpm, and the Hz will be increasing too. But the g/s already pegged early, so the ECU only saw approx 200 g/s. If you change the maf table to something like I have attached in the 2nd photo, hopefully you will see higher g/s as your rpm increases. I also gave the table a bit more resolution at the start too. All of those new figures are calculated, not just guesses. Close enough for you to see if it changes anything in your logs and help with diagnosis of your issues. I hope the pic is clear enough. Pic 1 is before, Pic 2 is after.

    Click image for larger version. 

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    Last edited by OzDuramax; September 6th, 2017 at 04:30 PM. Reason: Spelling

  6. #16
    Senior Member SV8346's Avatar
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    Quote Originally Posted by OzDuramax View Post
    As you have already mentioned, your actual airflow past the maf will be increasing with rpm, and the Hz will be increasing too. But the g/s already pegged early, so the ECU only saw approx 200 g/s. If you change the maf table to something like I have attached in the 2nd photo, hopefully you will see higher g/s as your rpm increases. I also gave the table a bit more resolution at the start too. All of those new figures are calculated, not just guesses. Close enough for you to see if it changes anything in your logs and help with diagnosis of your issues. I hope the pic is clear enough. Pic 1 is before, Pic 2 is after.

    Click image for larger version. 

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    Unfortunately it doesnt show the figures clear enough or maybe my screen doesnt have good enough resolution. Any chance you could pm me the figures from 0 g/s up to max flow so i can compared them to what mine is doing.
    2016 RG Colorado 2.8TD

  7. #17
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    hey there, just found another table that is urgently needed for the Colorado's here in NZ. The table I found in this video :
    https://www.youtube.com/watch?v=HKu80j0bUHk detailing some tuning on a LBZ engine. The table is called B1122 Torque Fuel Limit RPM conversion.
    I'm assuming theres a similar table in the LTZ Colorado as its the same ecu USED IN EACH. When I'm tuning these engine the fuel hits a brick wall at 104mm3 and flat lines until the commanded torque starts to drop off over 3200rpm. It just happens that this table in the video has a figure of 104mm3 in it which is what I am getting as a brick wall.
    Can you confirm this is the problem ?
    O/S 55500370

    thanks,
    Mike Ekdahl in NZ
    "Just a tune > yeah right !!!! "

  8. #18
    Lifetime Member GMPX's Avatar
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    Mike the LBZ used a Bosch ECM with Bosch software, the Colorado is using a GM ECM with GM software, totally different.
    I no longer monitor the forum, please either post your question or create a support ticket.

  9. #19
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    MMMM well I wonder what setting is pegging my fuel at 104mm3 maximum. I'm going to up the pulse width table by 5% in that area to see if that gets for fuel in the engine.

    cheers for the reply
    "Just a tune > yeah right !!!! "

  10. #20
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    Quote Originally Posted by The Alchemist View Post
    hey there, just found another table that is urgently needed for the Colorado's here in NZ. The table I found in this video :
    https://www.youtube.com/watch?v=HKu80j0bUHk detailing some tuning on a LBZ engine. The table is called B1122 Torque Fuel Limit RPM conversion.
    I'm assuming theres a similar table in the LTZ Colorado as its the same ecu USED IN EACH. When I'm tuning these engine the fuel hits a brick wall at 104mm3 and flat lines until the commanded torque starts to drop off over 3200rpm. It just happens that this table in the video has a figure of 104mm3 in it which is what I am getting as a brick wall.
    Can you confirm this is the problem ?
    O/S 55500370

    thanks,
    Mike Ekdahl in NZ
    We always are able to and you should be able to get to 120mm3. I have had others send files with same issue you are seeing....don't fudge the pulse table...

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