Re:Whittlebeast's RPMxMAP vs Duty function

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Re:Whittlebeast's RPMxMAP vs Duty function

Postby robs » Fri Oct 07, 2016 4:30 pm

Continued from here.

whittlebeast wrote: Re: Making EGO correction slower

I pictured something similar to warmup enrichment with sliders to develop the primary fueling curve. MAPxRPM along the bottom and Base Duty Cycle up the left. To do early tuning, you would simply put your motor at a load and slide the closest slider up and down till the EGO correction was close to 100. Then move up to next higher load (MAPxRPM) point and repeat.

Once you have a reasonably close base tune, you could move on the a Speed Density multiply correction table that starts at 100 everywhere. I bet MLV autotune could be modified to automate this process.

Here is what my 300 hp supercharged jet ski looks like.

http://www.nbs-stl.com/motec/MAPxRPM%20 ... 0Motec.png

Ironically, my personal ITB motor running MS3 is not a very good candidate as a test mule. It would at least need a Alpha-N correction table. We need to start a new thread to take this much farther.

Andy


What you've described here is how it might appear in TunerStudio. I haven't done much with customising TS and was mostly interested in the MS firmware changes (if any) that you had in mind. It seemed to me that, if there is a simple functional relationship between MAPxRPM and Duty%, then removing the 2d VE table would be the natural approach. A pretty radical idea, but it bears thinking about.

To make it work as you describe would at least require some firmware changes. You favour the RPMxMAP vs Duty graph, but I'm still pretty sure this is equivalent to the computationally simpler MAP vs %ReqFuel (PW). So the firmware would need to support this 1d interpolated graph and a suitable control+gauges would need to be added to TS. Whether the VE table is removed altogether or becomes a fine adjustments trimmer I'm not sure (not much headroom in MS2).

I'm happy enough to look at coding something, but it's a pretty big change and there's every chance I have hold of it by the wrong end. Would like to hear James's and Ken's views.

In any case, it is an interesting approach and I will definitely be taking a look at my current tunes through this lens.

Finally, just to put a picture to the graphical difference between MAP->PW vs MAPxRPM->PWxRPM, graphing the four points: (1000, 30, 3ms), (4500,30, 3.5ms), (1000, 90, 11ms), (4500, 90, 11.5ms) both ways gives:

xrpm.jpg
Effect of x RPM
xrpm.jpg (16.54 KiB) Viewed 1268 times

So it kind of zooms in on the high load, high RPM stuff giving a more detailed view of the most critical region.

Have fun,

Rob.
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Fri Oct 07, 2016 5:24 pm

Robs, could you post up a fairly large data log off your motor? Some motors fit the "model" better than others. Stock motors and turbo motors are the best for this. ITB motors are the worst.
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby robs » Fri Oct 07, 2016 7:42 pm

They don't come much more stock than mine!

Log sent by e-mail.

Have fun,

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Fri Oct 07, 2016 8:21 pm

Your motor has tuned out about as "textbook" as it gets. It should work fine.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby muythaibxr » Sat Oct 08, 2016 4:32 am

Robs: If you have time to mess with it, go for it. My test mule has ITBs which is the main reason I have not tried it.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 7:43 am

I'm trying to follow what you guys are doing...

After a tune is established with an ego swing of less than +-3%, plug in map x rpm to pw into a scatter plot and it should look like a straight line. If it doesn't then there is a problem/something different with your engine or ve table...?

I have a mass airflow sensor wired up to adc7 buts it's not driving fueling at the moment. Shouldn't it provide the same linear output as rpm x map to pw? Do adc7 to pw? I have several dozen logs of my drive to and from work using ego correction using a narrow band. I can send those to someone if it would be helpful. I also have several of just driving using a wbo2 without correction.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 12:26 pm

Robs,
Why not repurpose the MAF transfer curve? Change the g/s to RPM x MAP. I don't know the depths of changing that but the memory should already be set aside.

Could you start a new code chain, 4.x.x with the big code changes and crazy ideas for testing theories and such.

I'm running a sbford 306 and a smallish turbo. Port injection.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby robs » Sat Oct 08, 2016 3:39 pm

ol boy wrote:I'm trying to follow what you guys are doing...

Me too.

ol boy wrote:After a tune is established with an ego swing of less than +-3%, plug in map x rpm to pw into a scatter plot and it should look like a straight line. If it doesn't then there is a problem/something different with your engine or ve table...?

I think the idea is to turn it around the other way. Why bother with tuning the whole VE table when you "know" that the scatter plot of a good tune falls along a (not necessarily straight) line -- just work out the line and you're done. Besides the reduced work, what I think is particularly attractive with this is that holding to a particular point on the MAPxRPM line will be really easy compared to holding both MAP and RPM steady as VE Analyze Live likes. RPM dropping? Put your foot down a bit to hold MAPxRPM steady. It should feel pretty natural.

I expect you'd still want the 2d AFR target table for feedback for lean cruising/small corrections.

Your idea of using the MAF handling sounds spot-on. Only problem being I haven't any experience with it. But it definitely makes sense to me that what we're really talking about is combining a MAP sensor with RPM to simulate a MAF sensor.

This (assuming it works) would make new tunes of fairly run-of-the-mill engines much easier. Would need to keep the VE table for ITBs or other engines where RPM dependent gas dynamics mess up the thin line rule.

I'm only interested in this change if it's in the running to become part of the supported firmware. I can't start a new "code chain" since it's not mine to fork. I do like the idea of an entirely experimental firmware for MS2, but that's a different subject.

Ken: I have plenty of other things I can do, but this sounded interesting. I'm not that keen to try it on my daily driver and Andy doesn't have anything suitable, so it might be that the lack of a test mule is the real sticking point.

Have fun,

Rob.
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Sat Oct 08, 2016 3:58 pm

Rob, If we do a proof of concept in MS2 AND it shows promising as an easy way to tune typical builds, Ken or James are both interested enough to consider rolling the concept into the release version on MS2 and MS3.

My bet it is we will find it very similar to table blending with MAPxRPM as the base fuel table. Speed Density or Alpha-N would the multiply by table and fine tuning done with VEAL.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 4:37 pm

I drive my test mule 50 miles a day both city and freeway driving. Every time I drive the car it's a test drive!

I work at HFE INTERNATIONAL and we are using a smaller less featured version of a microsquirt module that DIY licensed to us running both small 2 stroke and 4 stroke singles for UAS platforms. Normally we mount the engine on a small engine dyno and load the engine to a set speed and increase the throttle from closed to WOT. We do this for every rpm to cover the entire VE table. We then mount the engine on one of four test planes and fly it around and tweak everything from the ground over a RF link. Quite the process to establish a tune for a new engine. From my perspective a single map x rpm to pw curve would shorten the development time to bring up an engine tune and deliver to the customer.

Would we get the same results with tps x rpm to pw? I have several data logs from a 120cc twin 2 stroke for comparison. 2 stroke engines don't do MAP very well.

On the front page of our website is a DA120 with EFI video. You can get a good idea of throttle control and the fuel requirements when doing 3D flying with a large scale RC airplane.

Hfeinternational.com

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby dontz125 » Sat Oct 08, 2016 5:01 pm

ol boy wrote:2 stroke engines don't do MAP very well.

I threw a suggestion for strokers a few weeks back, measuring exhaust header pressure and crankcase temperature for SD tuning. I have no means of testing this right now. Is this something you might be able to try at some point?
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Sat Oct 08, 2016 5:06 pm

That would require a new thread.
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 5:06 pm

I read that. Problem I've seen with crank case pressure is that is moves... moves some 90 crank degrees over the rpm spread. I first tried measuring case pressure and had a good luck at a set rpm/load and map angle. Advance the throttle and the center of the lowest MAP value would shift. I later oscoped the map analog output and found it moves and pressures will be around 70kpa to 130kpa at idle and 30kpa to 170kpa at wot.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 5:07 pm

whittlebeast wrote:That would require a new thread.

Sorry, will do.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby dontz125 » Sat Oct 08, 2016 5:08 pm

Sorry - thread hijack. :oops: I can't erase my post now that it's been answered. Can a mod cut this away?
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby robs » Sat Oct 08, 2016 6:16 pm

Andy: ok, I'll look into table blending, MAF handling and I think I'll have to look at TunerStudio too -- It's very configurable, but I wouldn't have expected VEAL to be able to understand this. I've only tuned two mundane cars though, so what do I know. It may take me a while to get a good handle on all this -- I only take new things on slowly.

ol boy wrote:I drive my test mule 50 miles a day both city and freeway driving. Every time I drive the car it's a test drive!

Would we get the same results with tps x rpm to pw? I have several data logs from a 120cc twin 2 stroke for comparison. 2 stroke engines don't do MAP very well.

Interesting workplace you have there Ryan.

I have my doubts that the tps x rpm translates cleanly into air flow for those engines. I only have 2-stroke bike experience, but the whole effect of expansion chambers was to make the gas throughput non-linear to RPM. Maybe those plane engines have disc-valves which might reduce the effect. Anyhow, we can check those log files. It won't be hard to try a few scatter plots and see how they look. One of those engines might make a good test platform, and I'd be less worried about leaving you stranded on the freeway.

Have fun,

Rob.
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Sat Oct 08, 2016 7:05 pm

I have some good inside contacts at MLV. I bet we can get the autotune part nailed fairly quick. :D
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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sat Oct 08, 2016 9:35 pm

Robs,
I'm not to worried about being stuck on the freeway. Happens at least twice a year. I'm due for sure. Never a MS problem but more of a 53 year old car problem. In fact I was smashing through some transmission code tonight and made some big changes, I'm sure it will hang up or do something unexpected Monday morning.

The 2 stroke engines are a reed valve type. We also have a piston port type from a different manufacture.

6 months ago I hung a modded Ford MAF on the DA120 and logged the airflow/pw/afr to create a transfer curve. I plugged in the curve but forgot to 100 out all the cells in the VE1 table which still had the alpha-N values. I kept adjusting the MAF curve to get the afr correct. Ended up with a straight line as a result. Does this tell me I had a pretty decent VE table to begin with? After I realised what was going on I 100 out all cells in VE1 and redid the MAF curve. Motor ran and responded very well with MAF. I was dumb founded for some time as to why it just worked so well. We put about 40 minutes of actual flying on it. First ever flying Ford MAF element.

Later Ryan

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby whittlebeast » Sun Oct 09, 2016 4:10 am

One of my early MS toys was a two stroke jetski. It had a Ford MAF running MS1 on really late MS1 code. It was not too long after that time, we found that on most "standard" motors, plotting MAPxRPM vs MAF created almost a perfect line. In those days, we were graphing this stuff in Excel. That testing was what got the programmer at MLV to start developing MLVHD with all the scatter plot stuff that later developed into Histogram views. The idea of scatter plot filters evolved from this and what he have already done to get VEAL to work. The same thing happen with the smoothing function in MLVHD. This stuff is all tied together as we found new ways to understand engines and code to tune them.

The MS world was the first in the EFI industry to work on ways to tune motors without the requirement to use a dyno for the entire process.

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Re: Re:Whittlebeast's RPMxMAP vs Duty function

Postby ol boy » Sun Oct 09, 2016 6:46 am

I was looking at some logs over the past 2 months from the wagon. My map x rpm to maf creates a mostly straight line. It has a slight upward curve but with a little hook near the idle region. I'm wondering if the shape of this line will indicate injector dead time being to big or too small.

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