Boost tuning with VersaTuner

Discussion of tuning specific to MAZDASPEED3/MAZDASPEED Axela/Mazda 3 MPS vehicles
mituc
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Boost tuning with VersaTuner

Post by mituc »

Now, we all know that the versatuner does not support pure boost tuning. However, sometimes this is necessary (a necessary evil I'd say, because I hate boost tuning) especially for those who have a larger turbo on the car and the boost control with aftermarket EBCS isn't that great with the tables available in versatuner (basically only 3 control tables, the mighty BCS DC Base table, the BCS DC IAT Adjustments and BCS DC Adjustment - Load corrections).

Now, boost tuning in VT can be done as Steve mentioned several times on this forum pretty much like this:
1. set the MAP limit to the desired value (in both throttle reduction and fuel cut tables);
2. raise the load at a high but still safe value;
3. tune the BCS DC table accordingly to obtain the desired boost at that RPM, ideally after you've gone through a load tuning session, took some logs and figured what WGDC is necessary for obtaining about the desired load/boost at each RPM point;
4. zero the BCS DC load correction tables to prevent the wastegate duty cycles go higher or lower from target.

Now, here comes my problem and question:
- let's say that I did my tune during summer, or, at least mid/late autumn when the ambient temperatures were still well above freezing;
- with my hypothetical tune I'm getting a load of 1.9 between 6000 and 6500 which I'm happy with, as the injector duty cycle is still around 85% (I'm not sure, I'm just making this numbers up, but I'm not far from reality);
- freezing temperatures come;
- now I'm getting a load of 2.05 at the same boost which I'm not happy with anymore because I don't want more than 1.9 because at load 2.05 the injector duty cycles go into the low 90's and I don't want that.

As we all know, reaching the injector duty cycle limit will make the ECU trigger some WGDC adjustments as well. Is it safe to rely on the injector duty cycle limit in this kind of situations?
With the BCS DC load correction table all set to 0 and fixed BCS DC values the load will vary with temperature only basically, and at some point we may not want it to go above a certain value, and this injector duty cycle limit would be the last resort. Will it work?
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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Steve @ VersaTune
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Re: Boost tuning with VersaTuner

Post by Steve @ VersaTune »

If you want to use that strategy, only zero out the underload half of the load correction table. That way when you exceed your load target, you will still reduce bcs dc.
mituc
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Re: Boost tuning with VersaTuner

Post by mituc »

Thanks Steve, that's how I'm doing it now (basically only the 3 values from that table, when the load is exceeded too much), thanks for confirmation!
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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Steve @ VersaTune
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Re: Boost tuning with VersaTuner

Post by Steve @ VersaTune »

There are other tables related to load correction for the BCS DC. We will add them to VT some time in the future. There is an initial percentage and then the incremental percentage. The initial percentage is not in VT yet.
EmPeEs6
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Joined: November 25th, 2013, 5:54 pm

Re: Boost tuning with VersaTuner

Post by EmPeEs6 »

So, a (long...) couple of years later, I would like to reopen this interesting topic (although it is a real challenge to try to go this way using VT).
What about this idea (for simplification, let's assume that wgdc 50 throughout the whole rev range approximately result in the desired boost values of ~245 kPa=21 Psi):
- set all target load limiting values to some not reachable max of let's say 4 and leave the load correction tables stock (or slightly reduced).
- set WGDC for WOT (throttle pos 68.75 and above) to 35 and WGDC max increase to 20 (resulting in a max. possible WGDC of 55).
- set WGDC for part throttle operations (below 68.75) to some significant lower values (0...10) -> the maximum possible value must lead to some "uncritical" boost of e.g. 220 kPa).
- set the boost limit throttle close table to: <desired target boost + 5...10 kPA> (e.g. 250 kPa).
- set the boost limit fuel cut table to: <desired target boost + 15...20 kPA> (e.g. 260 kPa).
- adjust the values in "BCS DC Adjustment - Boost Limit Exceed" according to the load error correction table(s):
Since WOT target load is far out of reach, the WGDC (initial+incremental) corrections will always be max (i.e Base-WGDC+10+0.24+0.24+0.24...) until max. allowed WGDC (=Base-WGDC+20) or throttle close boost limit is reached,
you set the boost error correction values to -0.23 all across the board. This way final boost will be stuck around your target boost.
- In order to control WGDC and thus boost/load for part throttle conditions better, you should set target load for these APPs to some
reasonable low value, whereas target load for WOT conditions (APP ~100) should be set to 4 again.
Furthermore, the requested rel. throttle opening angle should be kept significantly below 70 for low to mit load values and 80 for high load situations (WOT).

This is a rough, simple approach which might work...Any comments?
mituc
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Re: Boost tuning with VersaTuner

Post by mituc »

These values will vary from car to car depending on the setup, ambient conditions, and so on.

However, mind that the MAP/boost targeting tables actually works. But of course you will have to set the boost comp table accordingly based on what EBCS you have.
You can still use the load tables to keep the load in check but set it to a reasonable value, say 2.3 or so, not 4.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
EmPeEs6
Posts: 20
Joined: November 25th, 2013, 5:54 pm

Re: Boost tuning with VersaTuner

Post by EmPeEs6 »

Hi mituc,

nice to read you again (meanwhile I switched from a MS6 to a MS3)!

Well, I do not really intend to try this out, since it is actually no good idea to imitate boost tuning without having access to the relevant boost error correction tables ;-)
Nevertheless, it would be interesting to see if my suggestion works...From my point of view there's no other way to control boost under wot conditions on a safe level without using the load targeting logic.
Dolfius
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Joined: May 31st, 2017, 2:54 am

Re: Boost tuning with VersaTuner

Post by Dolfius »

mituc wrote: July 3rd, 2020, 5:01 am However, mind that the MAP/boost targeting tables actually works.
The table information says at the bottom "This is an operating mode only used during development"

How do these come into play? From what I understand, the Over Boost Protection tables will ensure boost (and subsequently load) wouldn't go above whatever it's set to.

BCS DC Base and the Load Target tables take care of achieving load (and pretty much boost) for the most part. With the relevant comp tables keeping it in check as well.
How does that table affect the bigger picture?
mituc
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Re: Boost tuning with VersaTuner

Post by mituc »

Boost != load.
Or, boost = load but only if you keep the humidity, ambient temp and BAT the same, which you can't. By example during winter you can hit load 2.4 with 22PSI of boost around say 4000rpm, during summer you may need 24PSI for the same thing.
This also varies from car to car, depending on the flow mods each have.

So you can load tune and set a boost limit in case during certain conditions the boost may go above some value you don't want to cross (piping, turbo speed and overheating, and so on) - and this is the OEM and classic approach, or you can boost tune but set a load limit in case with less boost than you normally run you may hit load values above which you don't want to go (due to certain reasons such as engine strength concerns, fueling availability, whatever).
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Dolfius
Posts: 64
Joined: May 31st, 2017, 2:54 am

Re: Boost tuning with VersaTuner

Post by Dolfius »

mituc wrote: July 3rd, 2020, 10:21 am So you can load tune and set a boost limit in case during certain conditions the boost may go above some value you don't want to cross (piping, turbo speed and overheating, and so on) - and this is the OEM and classic approach, or you can boost tune but set a load limit in case with less boost than you normally run you may hit load values above which you don't want to go (due to certain reasons such as engine strength concerns, fueling availability, whatever).
Flow = load, actually. 21 psi on a k04 and 21 psi on a bigger turbo will not yield the same load. I understand the principle.

What you're referring to there seems to be the over boost protection and load limit protection tables. Along with the requested load tatgets, correct?

I'm referring to the MAP Targets (Boost Targeting Mode) table specifically. What does that do? How does that come into play?
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