Full speed density system for Subaru

Developer topics relating to software that provides a tuning UI to alter ECU code and data

Moderator: Freon

Full speed density system for Subaru

Postby Freon » Mon Jul 02, 2007 10:54 am

Thought I would briefly share some of what I've been working on for the 32bit DBW Subaru.

This is a fairly well featured speed density fueling system. The VE map still needs tweaking, as does throttle tip-in, but it does work across all load and RPM effectively.

http://freon.shackspace.com/car/ecu%20a ... nsity1.avi
http://freon.shackspace.com/car/ecu%20a ... nsity2.avi
http://freon.shackspace.com/car/ecu%20a ... nsity3.avi
http://freon.shackspace.com/car/ecu%20a ... nsity4.avi

Nothing is released for general consumption yet, but hopefully soon once I'm a bit more confident in it, and can give a good base VE map for people to use to start.
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Postby salex » Tue Jul 03, 2007 12:10 am

Wow Freon! Excellent work! Can't wait to try it!
It would solve so many of our problems...
When do you think it will be officially included in ecuflash?
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Postby Freon » Tue Jul 03, 2007 3:46 am

I don't think there is anything to gain by "including" it in Ecuflash as it is just a binary patch. I will probably post patched ROM files and associated updated XML for Enguinity, Ecuflash, and Ecuedit.
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Postby FrSTi » Wed Jul 04, 2007 12:11 pm

Looks good !
And glad to ear your voice :D

Well done Freon ;)
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Postby Multiades » Sun Jul 15, 2007 5:47 pm

Are you calculating based on VE and density, ie true theoretical speed-density, or do you have a 3D fuel map by RPM and load (as MAP)?

In my tuning experience (AEM EMS) the theoretical method doesn't work very well and 3D mapping is quite necessary.

-Chris
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Postby Freon » Mon Jul 16, 2007 5:38 am

It is theoretical (calculated) rather than just an injector pulse width map. So all factory fuel trims are in place. The VE map is 3D. It seems to work quite well so far, even cold vs warm engine.
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Postby Multiades » Mon Jul 16, 2007 7:24 am

Freon wrote:It is theoretical (calculated) rather than just an injector pulse width map. So all factory fuel trims are in place. The VE map is 3D. It seems to work quite well so far, even cold vs warm engine.
Interesting! Willing to post screenshots of the map?

Ideally, a 2D VE map + density calculation would make it a snap to just punch in AFR values and run with it, like the factory mass-airflow system, which I find quite novel coming from the AEM. There isn't really a practical difference between a 3D VE map and a pulsewidth map. If VE is changing with pressure (density), it's because a linear VE calculation isn't detailed enough to consider all factors.

For example at an idle intake manifold pressure of -10psig, the exhaust manifold pressure is at least 0psig. At an intake manifold pressure of 0psig, the exhaust pressure could still be close to 0psig (or maybe not at high RPM). At +20psig intake, the exhaust manifold pressure is almost certainly very high -- +20psig or more -- and could double from low to high RPM. Since we only have access to intake MAP and not exhaust manifold pressure, we can't build a model formula that "knows" how much air is passing through the engine -- never mind the fact that we'd have a hard time quantifying an engine's sensitivity to exhaust pressure.

Not knocking what you're doing, I just wanted to open a discussion on fueling methods. The simplest way IMO is just to 3D map the entire engine and forget about "VE", which is a useful concept to understand cylinder filling but is of relatively little practical value in engine management. It sounds like what you've done is the same thing, but with different numbers in the boxes. In the end either method ends up being user-transparent; whether the number in the box is called "VE", "pulsewidth", or "raw", the map looks the same.


EDIT: I suppose you could have two 3D maps (which is redundant and confusing): one VE map, and the other an AFR map. Increasing one cell and decreasing the corresponding cell on the other map would cancel each other out. This philosophy might be an extension of the ideal where the factory management is measuring total air mass into the system and can easily calculate how much fuel to balance it to a specific AFR (novel to me, having had no experience with that before).

Much easier just to have one map.

-Chris
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Postby Freon » Mon Jul 16, 2007 8:58 am

Don't worry about it. I know what I'm doing.

This is only an injection of code in place of the MAF scaling table. Instead of looking at the MAF scaling table to get a total airflow number, it is calculated based on intake air temp, VE, MAP, RPM, and a few other compensations I am deeming necessary as my testing progresses.

Everything else about the factory ECU is in tact! The factory fuel enrichment maps are still in place. There are many reasons I took this approach, and so far I'm feeling pretty vindicated for it, as it works very well.
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Postby Multiades » Mon Jul 16, 2007 10:36 am

Freon wrote:Don't worry about it. I know what I'm doing.
I'm sure you do. Clearly it works, and I'd love to see the final result.

-Chris
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Postby 2.5l of fury » Tue Jul 31, 2007 3:39 pm

Any update on this Freon?
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Postby 2.5l of fury » Fri Aug 24, 2007 4:37 pm

bump
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Postby Freon » Fri Aug 24, 2007 5:12 pm

No updates right now. Still waiting for shbootmode to further develop anything.
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Postby Jon [in CT] » Sat Aug 25, 2007 6:05 am

Freon wrote:No updates right now. Still waiting for shbootmode to further develop anything.
Yesterday the latest (1.31) EcuFlash became available and it supports shbootmode.

http://www.openecu.org/index.php?title=EcuFlash
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Postby KillerKam12345 » Wed Oct 03, 2007 6:38 am

FREON ANY NEWS? IM DYING HERE!!!!!!!!!!!! LOL
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Postby wrxsti » Tue Oct 16, 2007 9:01 am

Yeah any updates?
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