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decel smoothing factor question

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decel smoothing factor question

Postby Action_B » Thu Nov 22, 2007 8:54 pm

Okay, i dont understand the decel smoothing factor.

To explain my confusion i will use a 2g eclipse for example

1. 2g eclipse come stock with a recirculating bypass valve, and when you release the gas, the ecu automatically throws some fuel in the cylinder for expected unmetered air. This is a normal condition.

2. Now that same eclipse is set to vent to atmosphere. In this case, when you let off the gas, the car again automatically throws some fuel into the cylinder for expected unmetered air, however, the air isn't there because its not recirculating. In this case it seems that the car would stall from running too rich.

Now the question, Would the decel smoothing factor be for the 2nd instance?

If not, then what is it for
If so, then why does your ecu+ manual say the following:

"Under decel conditions,
some cars with vent-to-atmosphere (VTA) compressor bypass valve setups will stall because of leanconditions caused by dumping previously “counted” air to atmosphere. By using decel smoothing,
the ECU+ can compensate for this dumped air and reduce or eliminate stalling on decel."

It seems either backwards or i have misinterpreted the usage of this feature and how it works. Please anyone clear this up for me.
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Postby honki24 » Fri Nov 23, 2007 11:43 am

It would be for the second instance. But... Tom has admitted that it doesn't really work well. (last I heard)

It should say "rich conditions" btw.
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Postby tlcoll1 » Fri Nov 23, 2007 10:02 pm

Yea, I don't recommend using either of the "smoothing" features. What it does is "slow down" the changes in air flow values under either idle or deceleration. My understanding was that with the VTA BOV, when you let off the gas, you'd get a "jump" in air flow, and this feature removed the jump and replaced it with a smooth drop-off. I'm not sure that's the right answer any more.

I'm interested in changing this feature to be useful, so I'm looking for someone (local to MD would be perfect) who has a setup with a VTA BOV, where it's a snap to switch back and forth between vented and unvented. With that, and some logs with only a change between vented and unvented, I can probably make this feature fix the VTA problem.

Anyone want to volunteer?

Tom
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Postby Action_B » Fri Nov 23, 2007 11:54 pm

I can do it if no one else volunteers. I'm from Va. Beach. But i often go up north to visit family. Its near D.C. area so it would only be 30 minutes or so to get there. I'll probably head up there in a couple of weeks on my winter break from college.
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Postby tlcoll1 » Sun Nov 25, 2007 12:22 am

Ok, maybe we can work something out. I'll be available in the day most of December.

Tom
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Postby honki24 » Mon Nov 26, 2007 12:23 pm

I would guess that you would need to implement some sort of fuel back off under a certain TPS % decrease in under XXX amount of time. Basically you would need to implement a lean condition for when you snap off the throttle. I would guess you would just do some thing like " Under XXX TPS% decrease within XXX milliseconds, multiply MAF input by XXX" Where the multiplication would be something like 0.5, the time would be something like 400 milliseconds, and the throttle% decrease would be something like 25%. I would usppose you could make these parameters user configurable. Seems easy enough. lol but then I'm no EE either.

You know.... you could try this on your own evo. Just pull the DV out of the intake tube and go to lowes and pick up a 2" PVC plug for the tube. Very easy to interchange.
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Postby tlcoll1 » Mon Nov 26, 2007 11:21 pm

Interesting. That's similar to the "condition" part of how it works now. I think I am correctly sensing the time when the condition occurs, but I'm not doing the right thing.

Also interesting that I could do this on my car. Probably worth a shot. Thanks.

Tom
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Postby tlcoll1 » Thu Jun 05, 2008 11:49 pm

I was poking around a bit thinking about this topic, and I found that the GReddy eManage Ultimate has a feature that they call anti-stall. I figured out how it works, and it seems kinda clever. Seems like something I could steal and put into the ECU+. Anyone have this "stall with a VTA BOV" problem that would like to do some testing?

Tom
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Postby honki24 » Fri Jun 06, 2008 11:22 am

I would def. be willing to pull off my recirc tube and try it because I want to put my hard pipe intake back on that doesn't have a recirc tube... plus recirc makes too much air reverberate through my MAS.

Make me some kind of compatible version with this in it and I'll test it for you!

(btw you could test it too if you just pull your dv out of the intake pipe and plug it w/ a cheap plastic plug from any hardware store, bam intstant VTA BOV)
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Postby tlcoll1 » Sat Jun 07, 2008 6:59 pm

I was looking at my car, and stock it's kinda hard to get in there where the BOV plumbs in. And it's probably better for a real car to try this out. I'll work on this in a few days.

Tom
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Re: decel smoothing factor question

Postby da1sexmonk83 » Mon Jul 14, 2008 8:12 pm

Any progress? I have been having trouble with this too. I will drive around town, bov will activate and the car will shut off.
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Re: decel smoothing factor question

Postby tlcoll1 » Tue Jul 15, 2008 8:02 am

Been "done" for a while. I'm waiting for honki24 to give it a whirl and let me know how well it works.

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Re: decel smoothing factor question

Postby honki24 » Tue Jul 15, 2008 11:14 am

lol, oh... sorry I didn't know I was the official test mule... I'm waiting for a gasket to come in the mail to get her ready for the race next weekend. Tom, could you re-send me the most up to date beta? Please include any install info, seeing as I'm an ME... not an EE. (ie computers > me)

By the way, I hate the "save" button at the bottom of the posting screen... I always click it rather than "submit". Really aggrevating. Who saves their posts anyways?!
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Re: decel smoothing factor question

Postby tlcoll1 » Tue Jul 15, 2008 9:55 pm

honki24 - What you have is what I need tested, but I'll re-send it anyway.

da1sexmonk83 - Send me your e-mail address if you want to give this a try.

Tom
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Re: decel smoothing factor question

Postby honki24 » Sat Jul 19, 2008 1:52 pm

I was gonna try to test it today but I cant configure the screen. See the screenshot.
I'm still having trouble w/ the custom MAP btw. I went out tuning today and one time I began to log it wasn't logging boost again. I looked at the custom MAP configuration and it was all zeroed out again. Again, I don't know what triggers it. Plus, when I tried to reconfigure it and zero out the custom sensor a popup said something like "unable to configure this sensor".
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