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Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 6:22 pm
by Simon@FutureProof
I have been trying to get the E30 running a bit better on the alpha/N setup and I seem to not be getting any acceleration enrichment.
Going through the data logs I can see the occasional spike on the Fuel:TPS Change trace but my Fuel:TPS acceleration extra fuel is a 0.0ms flatline.
It is almost like its set to use MAP or another sensor instead of the TPS but I cannot find any settings to tell it what acceleration enrichment method to use.
I have tried adjusting the length and threshhold with little change.

I think there's a few questions here:-
1. Is there a setting anywhere to pick the enrichment method/algorithm?
2. Is the TPS based enrichment map still additional ms of pulse width like suggested in the Wiki and not %?
3. Do I simply have the trigger points set too high/low/wrong?

My steady state fuel table is all well to the rich side so the lean spiking is most certainly due to the lack of acceleration enrichment.

I have attached the logs and tune to this post as its much more obvious what I am getting at from the logs than my bad explanation.

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 8:26 pm
by AndreyB
-1. newer version of console would be producing a bit better log files.

0. Your log shows TPS which never goes above 0.5% - can you please confirm that your TPS gauge ever goes above 0.5%? I wonder if that's a rusEfi scale defect or if your TPS is not calibrated or else?

1. No setting, it should just work as is - as long as your settings are reasonable.

2. it's ms, not %. What makes you think %? Is there any place where % is mentioned by mistake?

3. see #0

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:05 pm
by Simon@FutureProof
I thought TPS goes to 30.47% on the log? Certainly in the car I can get a full sweep of the TPS in tuner studio with no issues?

1 - Ok, no setting = no problem there.

2 - The Wiki has references to % but a note that it was in ms. I just wanted to double check.

3 - See #0 :lol: Could this be because I have done the TPS set up via TunerStudio and not the console?

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:09 pm
by AndreyB
I am not a smart person, I was looking at the wrong log. Sorry.

Can you please point me at the exact wiki page to fix while I am looking at hopefully the right log?

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:15 pm
by Simon@FutureProof
https://rusefi.com/wiki/index.php?title=Manual:Software:Fuel_Control

About 80% of the way down the page with a TODO;- note to change it.

Is there a master Wiki todo/fix list where these things can be logged? I don't mind pitching in capping new screen shots or correcting little things like this. Maybe a documentation subforum where we can work on this side of the project?

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:19 pm
by AndreyB
https://rusefi.slack.com/messages/CF8NQ1RU6/ is the place where documentation plans are being discussed. The strategy is to move from wiki to https://github.com/rusefi/rusefi_documentation

All TODO should be tracked at either https://github.com/rusefi/rusefi_documentation/issues or https://github.com/rusefi/rusefi/issues

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:30 pm
by AndreyB
Very rarely is "delta TPS" not zero on the attached log.

On top of that, https://github.com/rusefi/rusefi/issues/768 shows not the same rate of change/delta TPS value as the firmware uses while deciding on extra fuel amount, but in your case it would not change the fact that your logs usually show zero anyway.

Can you please try larger "length" value for TPS/TPS?

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:53 pm
by Simon@FutureProof
Sure, that is what has been confusing me, unless I am very rough with the throttle I am not triggering the TPS delta.

I did wonder about the "length" and if it was too short, the note on the wiki had me thinking it was the length of time enrichment was active for after the trigger event.
From the wiki - "The Length(cycles) specifies how many ignition events will be affected by the enrichment. This should probably be at least the number of cylinders in the engine, so each cylinder is a beneficiary of the enrichment."

Am I correct in thinking that this is actually the length of time to consider when checking for the TPS Delta? So a longer length is more time to achieve the throttle opening?
If so then I will absolutely go for a longer duration.

Re: Alpha/N and Acceleration enrichment

Posted: Sat Apr 20, 2019 9:59 pm
by AndreyB

Re: Alpha/N and Acceleration enrichment

Posted: Sun Apr 21, 2019 8:58 pm
by Simon@FutureProof
Ok, seems improved, I have set the length to 50 which covers about half a second @2000 rpm for this engine which is pretty reasonable. (Past research work has shown the fastest a human can go from cruise position to full throttle is around .3 of a second, GM did a lot of work on this for SAAB and sources of turbo lag).

What I am seeing is much better DeltaTPS response but limited enrichment shots. This seems to be purely due to the number of cells and break points available and how I had them set.
I don't think the steps were set fine enough for the low throttle opening points. So partly a tuning issue, partly a software issue.

Is there any reason I cannot set my X axis different to my Y axis?

So have 0, 1, 3, 8, 13, 25, 40, 65 on my X axis and Y set 1, 3, 8, 13, 25, 40, 65, 100?

This would offset my throttle start position by 1 cell and free up 8 more cells for tuning. I assume the software won't care what the axis on the table is it will just look at the "TPS Value" axis and check the correct "TPS Value to" cell?

Finally, is there any reason the table is not "TPS Value" on X axis and the value at the start of the current enrichment period and "TPS Delta" on the Y axis?
The reason I ask is it would solve the issue with only being able to use half the table and probably smooth the fuel enrichment out a bit as well.
If it's an easy change to make it "TPS Delta" instead of "TPS Value to" then I can flesh the concept out and even do a bit of testing now things are working.

Re: Alpha/N and Acceleration enrichment

Posted: Mon Apr 22, 2019 6:39 pm
by Simon@FutureProof
Regarding the table scaling question above - I just tried the car like it and it seemed to work ok, even just turning the car around on the drive I could get the enrichment to kick in, I just have to tune it a bit now.

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 1:26 am
by kb1gtt
OrchardPerformance wrote:
Mon Apr 22, 2019 6:39 pm
even just turning the car around on the drive
Was that with the e-brake, or did you turn it around purely with the long pedal :)

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 6:53 pm
by Simon@FutureProof
Wish I had :-
1. Enough room to manage that,
2. Enough of a base map to manage that,
3. A strong enough handbrake to manage that.

:lol:

Here is a log of it working much more effectively though. I did some cranking/idle fixing and tested the enrichment on some quick taps of the throttle at the same time.

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 10:42 pm
by AndreyB
OrchardPerformance wrote:
Sun Apr 21, 2019 8:58 pm
Is there any reason I cannot set my X axis different to my Y axis?

So have 0, 1, 3, 8, 13, 25, 40, 65 on my X axis and Y set 1, 3, 8, 13, 25, 40, 65, 100?
I would expect that you should be able to change X and Y independently?

Code: Select all

      xBins       = tpsTpsAccelFromRpmBins,  TPSValue
      yBins       = tpsTpsAccelToRpmBins,  TPSValue
      zBins       = tpsTpsAccelTable

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 11:36 pm
by Simon@FutureProof
It's seems to work just fine, so it's certainly an easy way to get a little more resolution from the TPS table.
That log above was taken with the axis offset and for now it is probably better if the axis are offset.
Considering we never need the "TPS from" value to be 100% as we would never be able to do a TPS from 100%/ TPS to 100% acceleration.
Offest axis TPS AE.JPG
Offest axis TPS AE.JPG (62.04 KiB) Viewed 10909 times
The reason I ask about TPS delta as the Y axis is again, improved resolution.
When considering the physics of the air/fuel in the inlet manifold it matters less what the numerical value of the TPS position reached and more how much change in air flow area we created and thus how much change to the air in the inlet ports.

Without digging too much into the physics we simply need to know what position the throttle was at when we started the change (the starting conditions of the air) and the TPS delta (how much we upset the air/fuel system).

Setting the table up as "TPS from" on X axis and "TPS Delta" on Y axis means we can set the table up as below and gain a lot of room for tuning.
The bese settings of the table is pretty simple as well, its just a curved surface, highest extra fuel at lowest "TPS from" and highest delta, lowest in the opposite corner and mid values at the other two corners. (see mock up below).
IPS Delta method.JPG
IPS Delta method.JPG (65.71 KiB) Viewed 10909 times
I think this is how some of the older OEM ECUs deal with this as well, when ROM space was much more of a premium a 5x4 table is enough to achieve pretty good enrichment once interpolated and corrections added.

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 11:37 pm
by AndreyB
OrchardPerformance wrote:
Tue Apr 23, 2019 11:36 pm
The reason I ask about TPS delta as the Y axis is again, improved resolution.
I would never have time to make the change, AND notify all the users about the change, AND update existing documentation :(

Re: Alpha/N and Acceleration enrichment

Posted: Tue Apr 23, 2019 11:42 pm
by Simon@FutureProof
How hard do you think the change would be? I'm willing to give it a try and test it out.

If it works I could probably write the documentation, after all if "its your stupid idea, your write the notes" right? :)

Re: Alpha/N and Acceleration enrichment

Posted: Wed Apr 24, 2019 12:07 am
by AndreyB
OrchardPerformance wrote:
Tue Apr 23, 2019 11:42 pm
How hard do you think the change would be? I'm willing to give it a try and test it out.

If it works I could probably write the documentation, after all if "its your stupid idea, your write the notes" right? :)
How important do you think it is? If I can use your skills I would really prefer to use your skills somewhere else pretty please. Very little time to play with all this and too many ideas. At the moment my focus is around https://rusefi.com/forum/viewtopic.php?f=5&t=592

Re: Alpha/N and Acceleration enrichment

Posted: Wed Apr 24, 2019 12:29 am
by Simon@FutureProof
Given we have a working method at the moment I would say it is a low priority, it would be more of an issue for something with large individual throttle bodies or that is very sensitive to air flow. The delta method should handle cumulative effects better just by nature of the way the table works.

With a perfectly functional method at the moment there is no reason this could not be shelved until more important things like the ETB are working.
The current method covers the most critical throttle movements so this would just be additional for drivability and final few % of power.