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Old 03-25-2009, 05:21 PM   #1
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Default AFR Target and Spark Standards...

Just wondering if there is a standard table for these for like anyone using MS on a 99. I understand everybody uses different settings, cause everyone's car is different. For my current application (see signature) what values should I be using for these tables? I am thinking, I shouldn't touch the Spark table, but perhaps my AFR targets look like ****. I VE analzed it yesterday after a few datalogs and it runs pretty good, I just want a second opinion of the AFR target afrtargets.vex

spark1.vextable.
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Old 03-25-2009, 07:36 PM   #2
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post up a screen shot of the afr table and i'll look at it.

i don't use the 8x8 table in MT, I prefer the 12x12 in MLV VEA but here is what I would use in MT
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Old 03-25-2009, 08:38 PM   #3
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The above link "afrtargets.vex" is my AFR target table, I clicked on export. For some dumbassed reason my computer is being difficult doing a screen shot. But yeah. my table was pretty different than the one you posted. I'll make a duplicate of the posted one, and then I'll give it a try.
Thanks.
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Old 03-25-2009, 10:17 PM   #4
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Yeah I know what a vex file is. I didn't feel like downloading it, starting up megatune, and importing your vex file just to view it.
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Old 03-25-2009, 11:11 PM   #5
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Hi paul! My table doesn't look mucch like yours either.. I based mine off someone else on this forum (can't recall who, but i think they had a good reputation!)

Quick questions -- i've seen a lot of tables where atmospheric pressure (101 or so) is high 14s, 15 vs. your 13.0. In general, your table looks quite rich even in mild boost..

Am i asking for trouble with my targets?
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AFR Target and Spark Standards...-targets.jpg  
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Old 03-26-2009, 12:57 AM   #6
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I don't know, but my car would hate that table^^^

Here's mine, recommended by Braineack as a good starting point, I think I changed a few cells.

Name:  AFRtargettabledl3-25.png
Views: 11
Size:  69.4 KB
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Old 03-26-2009, 01:19 AM   #7
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gospeed81, what's your max boost in PSI? I rescaled my table to better reflect my limited boost.. right now the highest kPa i hit is around 145..

-Tomaj
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Old 03-26-2009, 01:24 AM   #8
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Right now? 14.7psi absolute.

I will max at 10psi, and am going to rescale to about 180kPa, or like yours above. Haven't rescaled as I was more concerned with putting in bigger injectors today.

From everything I've seen, it's good to have about 20kPa headroom above your expected max to accomodate spikes, and linear interpolation for the noise on the MAP sensor.

Right now I'd say your table is good for almost 6psi.



EDIT:

Here is what my table looks like now:

Name:  AFR1.png
Views: 18
Size:  61.0 KB

It is a blend of Paul's table scaled to my expected boost level, with a few things I liked from my old table.

I ran a few datalogs this morning, and ended up with a very smooth VE that I like. Chirps them in second, with no hiccups or rich overrun from the RX7 injectors.

Last edited by gospeed81; 03-26-2009 at 09:54 AM.
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Old 03-26-2009, 11:14 AM   #9
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Quote:
Originally Posted by ctxspy View Post
Hi paul! My table doesn't look mucch like yours either.. I based mine off someone else on this forum (can't recall who, but i think they had a good reputation!)

Quick questions -- i've seen a lot of tables where atmospheric pressure (101 or so) is high 14s, 15 vs. your 13.0. In general, your table looks quite rich even in mild boost..

Am i asking for trouble with my targets?

I'd say so. What are you trying to accomplish by going leaner at atmosphere? Better fuel economy? I'm quite happy with my AFR targets and if I must say so myself my dyno graphs are pretty impressive. Truth be told though I have no idea how much power I make at 101kpa so if your goal is to beat me there by running leaner, I'll probably lose. Both my cars still average 27mpg.

FWIW, I did some testing back when I first got the parallel MS and WBO2. Hooked it up for logging purposes only, the stock ecu still controlled spark and fuel. AFR's dipped down into the high 10s at WOT over ~4100rpm. This is on a naturally aspirated car. Now that I call rich. Mine I call smart.
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Old 03-26-2009, 11:44 AM   #10
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I like gospeeds the best...but I run 11.5:1 above 8psi.
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Old 03-26-2009, 11:47 AM   #11
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Why do you guys have so many cells in boost in your AFR tables? Dont you run open loop when you are boosting?
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Old 03-26-2009, 01:18 PM   #12
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Quote:
Originally Posted by Duckie_uk View Post
Why do you guys have so many cells in boost in your AFR tables? Dont you run open loop when you are boosting?
You bring up a good point.

It's really a good idea to use the contour plot tool. Mine looks like this:

Name:  contourAFR.png
Views: 11
Size:  33.6 KB

And it shows I could still move some MAP values around.

Basically this should have more lines where you have more drastic, non-linear changes in target AFRs. Notice mine has a lot of concentration in normal vacuum operation range.

Just like a countour map of a mountain, there shouldn't me a lot of lines in areas that will have a linear rate of change in AFRs. In reality you could have two lines in boost, from 12.5 at say 110kPa, to 12.0 at your max boost, since the program does linear interpolation anyhow.

In other words, highly tune the areas where you have transitions between vac and boost, and throttle roll-on points. This should help throttle response, boost onset etc.

I'm still a newb, and may be wrong here, but I think you're right about wasting resolution in the boosted cells. I'm going to experiment with this slowly though.

EDIT:

If hustler posts his, you will see that he does the same on the ordinate axis, with rpms, ramping up to his boost cells. Fine tuning both should be beneficial.
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Old 03-26-2009, 09:56 PM   #13
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i guess i was going for emissions, my inspection is past due becuase i've been waiting on the MS working before i try to get inspected

I made some changes to my table, richened it up in boost, added more resolution near the on/off boost transition.

-Tomaj
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Old 03-26-2009, 11:47 PM   #14
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we use more resolution for tuning, then I played with mine a lot to get the most out of EGO correction in cruise.
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Old 03-27-2009, 08:58 AM   #15
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Quote:
Originally Posted by Duckie_uk View Post
Dont you run open loop when you are boosting?
No, do you?

Even if you do go open-loop in boost, there's value in having valid data up there so that VEA has something to chew on.
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Old 03-27-2009, 11:59 AM   #16
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OK so i went to the MVC (think DMV) inspection station today... For you non New Jersians, we have state run facilities as well as private. It was free so i figured i could get a clue as to where i stand.

I failed on two counts, one was the aftermarket horn, no big deal.. THe other was the emissions.

I went for two rounds

Test, Allowed Value, Round 1, Round 2
NOx - 1304, 750, 1806
HC - 166, 178, 185
CO - 0.93, 2.01, 1.83

Between the two rounds i did a little tuning which ended up leaning out the cells where the test was run. (Around 2000 rpm, 50kpa)

Do you guys know what would cause the excess HC and CO?? I figured too rich, so i made it leaner.. that helped with the CO a LITTLE but everything else got worse

-Tomaj
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Old 03-27-2009, 12:20 PM   #17
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Old 03-27-2009, 12:51 PM   #18
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See, now that's a good graph.
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Old 03-27-2009, 01:01 PM   #19
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You have too much CO and too much NOx. So you need to make the engine leaner and richer.


Seriously though, what's your ignition timing look like? Too much advance = high NOx, too little advance = high CO. You may have to finesse both mixture and timing to find the sweet spot. Put a little bit of fuel back in, and advance the spark a bit.
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Old 03-27-2009, 01:06 PM   #20
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Well WTF then? If i read the chart correctly, either i can do the 1304 NOx, OR i can do the 0.93% CO...?

I'm assuming that this chart doesn't take the catalytic converter into consideration -- in which case my question is -- what's a cat more effective at? Converting NOx, or CO?

-Tomaj
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