Another Load Question

Discussion of tuning specific to MAZDASPEED3/MAZDASPEED Axela/Mazda 3 MPS vehicles
Dolfius
Posts: 64
Joined: May 31st, 2017, 2:54 am

Another Load Question

Post by Dolfius »

Aye guys.

So today's question has two parts to it. First - is there a difference between Absolute Load and Calculated Load?

Secondly, I also saw the reported "load pegged issue" in my tunes - I could add WGDC, see more boost, car would feel stronger, yet load would be pegged at 2 on logs, while targeting 2.5 in the tune.

Here's the interesting bit though - if I wanted to see 2.1 load, I hd to target 2.6 in the tune. For 2.2, target 2.7 in tune. You get the idea - between the requested load and actual load achieved, there would always be that 0.5 difference.

Has anyone ever experienced this? Any theories as to why this would happen?
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Another Load Question

Post by mituc »

We work with absolute load. That is the value in percent or division relative to the volume of the engine which in theory you could fill in a normally aspirated mode. That is why this value can exceed 100% or 1.

As far as I know the calculated load is the amount of load you get as a percent from the total load requested. So if you're hitting 2.2 and requesting for 2.6 that's 100*(2.2/2.6)=84.6153.

However, if you need to target 2.7 to get 2.2 you may have a problem with the boost or load compensation logic/tables. If you could send me your tune and a set of logs taken with that very tune I could take a look.
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: Another Load Question

Post by Dolfius »

I'll do so once I have my car back.

Just recently rebuilt the motor and it went in to the autobody repair shop this morning. Once I have it back, it's go time again.

I'll see if I can share an old map and it' corresponding logs to you for reference in the meantime.
Dolfius
Posts: 64
Joined: May 31st, 2017, 2:54 am

Re: Another Load Question

Post by Dolfius »

Map and 2 logs attached @mituc. If you could have a look and give your input, that would be great.
Attachments
Data log - 2019-03-04 23.50.42.csv
(9.38 KiB) Downloaded 371 times
Data log - 2019-03-04 23.49.36.csv
(9.19 KiB) Downloaded 354 times
2019 Base V4 Rev5 v1.00.vtune
(110.17 KiB) Downloaded 353 times
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Another Load Question

Post by mituc »

The logs look pretty good and the car seems to be pulling well (even though 60-100mph could be lower, around 5.0 instead of 5.35-5.5s). But I'm not sure that whoever made your tune knows what he's doing...

Also, the spool is pretty bad... what turbo is that, an old GT3076 or is it a GTX3582?
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: Another Load Question

Post by Dolfius »

The 60-100 time is influenced by some variables though - gradient of the road, and me weighing around 125kg :lol:

The turbo in question is a T3/T4 china charger. .63AR hot side, .50 with a rather big compressor wheel.

I'm self tuning. If you were to compare the logs to the map itself, you'd see something doesn't add up. The load doesn't correlate with the given flow.

I'm still having the issue of not hitting the load targets set in my map, despite boost and flow rising. And even then I suspect the there is a table that's intervening. I logged a different map last night, which targets 2.16 load. Best it would give me was 1.941 I think. And the load was pegged at that for many cells, for a long time in the RPM range.

I can guarantee - if I were to up the load targets to 2.5 or 2.6, I would see 2.0 to 2.1 in my logs. And this is my whole issue - WHY is this happening?
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Another Load Question

Post by mituc »

Dolfius wrote: I'm still having the issue of not hitting the load targets set in my map, despite boost and flow rising. And even then I suspect the there is a table that's intervening. I logged a different map last night, which targets 2.16 load. Best it would give me was 1.941 I think. And the load was pegged at that for many cells, for a long time in the RPM range.
Well, First of all the boost limits are set pretty weirdly. This tune is clearly a boost based tune BUT the fuel cut limits are set lower than the throttle reduction limits except for some barometric pressure situations which can be met only at pretty high altitude. That will interpolate probably up to the BARO pressure in your area which hopefully are in the 90's kPa.
Secondly, even though the load targets are set to 3.2, the WGDC corrections allowed limit is set to 0%. This means that the ECU logic will work with only three things:
1. APP/TPS correlations and DBW tables;
2. commanded WGDC
3. boost limits.
This can be seen clearly in the logs you posted, the WGDC will cut to 50% abruptly at some point which is perfectly correlated with the WGDC table in your tune.
Dolfius wrote: I can guarantee - if I were to up the load targets to 2.5 or 2.6, I would see 2.0 to 2.1 in my logs. And this is my whole issue - WHY is this happening?
Hard to tell. But if you show us that tune with this happening and we may be able to tell you. However, if that tune is based on the one you posted then most probably there are a lot of things to correct and change there to make it work properly, progressively and predictably in all situations. Right now the car pulls very well at WOT, but the tune is far from being right.
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: Another Load Question

Post by Dolfius »

mituc wrote: Well, First of all the boost limits are set pretty weirdly. This tune is clearly a boost based tune BUT the fuel cut limits are set lower than the throttle reduction limits except for some barometric pressure situations which can be met only at pretty high altitude. That will interpolate probably up to the BARO pressure in your area which hopefully are in the 90's kPa.
Yes I'm situated about 1700m/5500ft above sea level. So around 84.5kPa/12.2psi Baro. This is why I only make adjustments to the the 11.27 and 12.41psi Baro lines in my tunes. I know if I drive to different altitudes I need to keep this in mind
mituc wrote: Secondly, even though the load targets are set to 3.2, the WGDC corrections allowed limit is set to 0%. This means that the ECU logic will work with only three things:
1. APP/TPS correlations and DBW tables;
2. commanded WGDC
3. boost limits.
This can be seen clearly in the logs you posted, the WGDC will cut to 50% abruptly at some point which is perfectly correlated with the WGDC table in your tune.
I have added WGDC corrections - by as much as 20% in some cases - to no avail. If I set the WGDC tables higher, it'll boost higher, but the load won't go up, and the AFR will lean out greatly. I suspect the AFR goes wonky because of the ECU curbing the load for whatever reason, but at the same time trying to hit the boost/WGDC targets (I'm guessing).
mituc wrote: Hard to tell. But if you show us that tune with this happening and we may be able to tell you. However, if that tune is based on the one you posted then most probably there are a lot of things to correct and change there to make it work properly, progressively and predictably in all situations. Right now the car pulls very well at WOT, but the tune is far from being right.
I've attached a map and logs taken last night that I hope will illustrate better what I am talking about.
Attachments
Data log - 2019-03-18 00.10.33.csv
(10.03 KiB) Downloaded 318 times
Data log - 2019-03-18 00.09.30.csv
(10.96 KiB) Downloaded 308 times
2019 Base Map Rev5 v1.04.vtune
(107.9 KiB) Downloaded 327 times
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Another Load Question

Post by mituc »

In those logs you're not logging MAP, only MAP voltage, and I guess you have a Bosch 3BAR, right?
Also, the throttle reduction MAP is set to 237kPa, that is roughly 22PSI of boost max which kind of match your air flow numbers (and the AFRs confirm the air flow numbers). This limit was changed in your REV4 V5 tune to 262kPa which allows for almost 26PSI of boost at your altitude...
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: Another Load Question

Post by Dolfius »

mituc wrote:In those logs you're not logging MAP, only MAP voltage, and I guess you have a Bosch 3BAR, right?
Also, the throttle reduction MAP is set to 237kPa, that is roughly 22PSI of boost max which kind of match your air flow numbers (and the AFRs confirm the air flow numbers). This limit was changed in your REV4 V5 tune to 262kPa which allows for almost 26PSI of boost at your altitude...
Correct. Bit of an oversight there with the boost limit tables. I apologize for that one.

Yes Bosch 3Bar MAP sensor. I didn't log MAP, but boost pressure and Baro pressure was logged- Boost+Baro=MAP as far as I understand it. So it can be a either or.

But it didn't get anywhere near the boost limit of 22psi set. I know VT uses load tune logic, so looking at the log the load is also off from the 2.16 target set in the map. And this is my issue. In the one log, the load is pegged at 1.925 from around 4500rpm all the way to 6000rpm. Even though the map has WGDC to work with, and a 20% WGDC correction to work with, it still only gave spring pressure (because 0% WGDC) and didn't get to 2.0 load at all. Which is incorrect. The load at that flow should be at the very least 2.1.


Why is the load getting pegged at 1.925? What table am I missing that's preventing the load targets from being reached?
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