VGT Tables for E98

[SV8346]

So what are our chances of being able to adjust the Turbo Target Vane Position tables in OS 55491998(DSP4 - 65491998). Seem to be able to adjust these tables in nearly every other OS that uses them but the poor little E98 gets forgotten about and pushed into the back ground when it comes to developments.

[Tre-Cool]

i've played with in hpt, majority of the time it's still hit/miss for changes. (could be hpt's fault) but for a stock turbo setup probably not needed.

[GMPX]

I understand it appears that nothing is happening with the E98 but it isn't the case, in the last three months we've had to add DSP4 conversion patches for several 2016 & 2017 US OS's, support for new OS's 55504430, 55500370 & 55488112. Fixed some speed limiter cal errors on early OS's too.
Unfortunately the Holden OS is a bit of a bugger to work with and unfortunately I never find the time to find those tables between managing all the other mapping, sorry, trying to make it happen. And to add to what Tre-Cool said, others have said the same thing, modifying them in HPT for example doesn't tend to get the results anyway.

[SV8346]

Yeah but for some reason i am finding that at full noise turbo cant seem to keep up or something weird? Desired boost and max allowed boost is set to 340kpa which i believe is above the Map sensors control anyway yet at full throttle at around 3000rpm the boost drops away slowly down to 270kPa yet the vane % is still showing 40% which is telling me that the turbo is still being restricted by 40%? Would this be correct?

[Tre-Cool]

100% is the vanes are fully closed (max response, spool up)
0% is fully open (bypass, max flow out rear etc)

I think these turbo's just dont have the flow capability for pushing that much air at those rpm's. Your not alone with the issue.

[SV8346]

100% is the vanes are fully closed (max response, spool up)
0% is fully open (bypass, max flow out rear etc)

I think these turbo's just dont have the flow capability for pushing that much air at those rpm's. Your not alone with the issue.

So yeah when its reading 40%, is still 40% restricted? Is that not correct?

[HOWQUICK]

So yeah when its reading 40%, is still 40% restricted? Is that not correct?

wouldn't it be fair to say it is restricting the vain trying to get the boost target you are requesting?

[SV8346]

wouldn't it be fair to say it is restricting the vain trying to get the boost target you are requesting?

From what i have read the standard OEM program max's out at 40%. No matter what you do engine wise it will still be 40% restricted, it wont allow the turbo to use the remaining 40% of the turbo's flow, this is why i am trying to edit the vane table to be able to use that 40% as well.

[Tre-Cool]

following on from what howquick is saying, you really need to think of the vane as a bleed off valve more than anything. if it can't hit your boost pressure with a 40% closed vane what makes you think it'll do it at 60%. all your doing is just spinning the blade faster & pushing the turbo cartridge past it's efficiency range = more hot air. hot air is less dense.

closed vanes slow down the gases out of the motor/exhaust as it's forcing it to turn the turbine. Technically you really want the vanes to be open more while keeping boost responsive, this in turn helps to drop egt's & increases efficiency.

The highest i have ever seen is about 90% for vane closed & 5% for fully open on a DPF equipped colorado when doing regen. Dpf regen process opens the vane all the open to bypass as much boost as possible (often going into vacuum, then switches to a really late injection timing to put heat into the exhaust & not the motor.

[SV8346]

Ok, so let me try to get my head around all of this,
At 100% its fully closed therefor creating the most restriction or creating faster airflow for low amounts of air into the exhaust housing?
At 0% its fully open therefor allowing more air into the exhaust housing and in turn allowing the turbo to spin harder if the exhaust gas is sufficient and then which in turn pushes more air into the engine?

So, if i was at 3000rpm and at 40% vane and allowing 60% of the air into the turbo to create 30psi of boost. Then if i maintained the same rpm yet i now allowed the turbo to open up to 10% allowing more air into the exhaust turbine therefor spooling the turbo harder and in turn creating more boost? Is that not correct?

[Tre-Cool]

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.

[SV8346]

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.

[OzDuramax]

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

[SV8346]

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?

[OzDuramax]

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.

21470 21469

[SV8346]

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.

21470 21469

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.

[The Alchemist]

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

[GMPX]

Mike the LBZ used a Bosch ECM with Bosch software, the Colorado is using a GM ECM with GM software, totally different.

[The Alchemist]

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

[HOWQUICK]

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...

[The Alchemist]

To confirm increasing the pulse width table between 100 and 120 mm3 and between 120 to 180 MPA puts more fuel in and circumvents the 104mm3 limit that the ECU clearly imposes.
Howquick, how to you increase this fuel limit ?

Thanks,
Mike

[GMPX]

To confirm increasing the pulse width table between 100 and 120 mm3 and between 120 to 180 MPA puts more fuel in and circumvents the 104mm3 limit that the ECU clearly imposes.
It does Mike but the ECM doesn't know about the additional fuel which will mess with its torque calculations which in turn means the ECM does not know the correct engine torque, it is a common tuning method but I think HOWQUICK is giving a big hint not to go down that path.
I know HOWQUICK is using just EFILive for tuning the E98 so there is a trick in there somewhere.

[Dmaxink]

A couple of notes FWIW.

1. Forget boost pressure. Think actual usable CFM.
2. Whatever you see the mm3 being in the top of the pulse table - increase your limiters/tune to match that top mm3 value within that axis. Dont tune around it.
3. Actual torque vs. calculated torque. If this model gets thrown off - shifting and drive ability issue will occur!
4. Forget the boost number - throw a AFR gauge on it (Considering you do not have manifold air density gauge) and see what what point the boost becomes useless.

[Chavez91]

There really isn't much need for a Manifold Air Density Gauge on the ECMs that calculate out the air mass per cylinder. Most ECMs already do air density calculations (including humidity) in the calculation of the air mass per cylinder. (E98 is on that list)

Plus, air density is an extremely easy calculation to make and add to a custom PID on EFI if you absolutely need it. In basic form its just the ideal gas law.... If you wanna add humidity to the mix, its only just a little bit more math to add to the equation.