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Old 08-09-2012, 03:57 PM   #1
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Default Continually leaner AFRs

And now, I'm down to my final problem with the car since the coolant has been more or less figured out.

Right now, if I start my Miata, it'll start at 11.8ish AFR, and when it fully warms up, it will idle at 10.8ish AFR.

If I shut it off for 5 minutes and turn it on, at fully warm, it'll idle at 11.5-12 AFR.

If I shut it off for an hour, it'll idle at ~14AFR when fully warmed up. And it will stay there, even if I drive it for awhile and de-heatsoak the whole SOB.

But wait, if I shut it off for an hour after the previous shut off, then start it up again, it'll idle at ~15ish AFR. And it will stay there, even if I drive it for awhile and de-heatsoak the whole SOB.

I'm 95% certain I have heatsoak issues going on. Since this is the last issue I have with the car that I haven't been able to fix, well, I'm stumped. I want to say it's related to GAIR, but the GAIR most people talk about is only lean restarts, not sitting at the same lean level at idle constantly. Ideas?
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Old 08-09-2012, 03:59 PM   #2
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warm-up enrichments, non-linear mat corrections. tune them.

watch your gammae enrichments. you should only tune your idle AFR when it's at 100%.
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Old 08-09-2012, 04:13 PM   #3
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Thank you very much Brainy, I'll give that a shot today.
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Old 08-09-2012, 10:44 PM   #4
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And it's working awesome, thanks Brainy! Cut GAIR to 50%, add in MAT corrections, gogo for win!
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Old 08-10-2012, 09:05 PM   #5
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I run ego correction above 800rpm on my MSPNP1 with EV14 injectors. Before I did this, it was a constant battle to manage the idle AFR's...constant tuning throughout the year...and the table IMHO has too few data points which makes it too linear. After enabling ego above 800rpm (instead of 1400rpm), the car runs absolutely fabulous in all weather conditions.

Some will say "Ahaha you can't do that! The computer is too slow and can't think that fast and will 'splode all over the road! AHAHAHA!!!" Well, I'm no electrical engineer, so I cannot confirm that the circuitry can't handle it...however...I am a mechanical engineer, and I can confirm that it hasn't 'sploded all over the road yet, and the engine runs exceptionally well with the ego settings I have used. Note that I HAVE refined the coolant-related AIT correction to get as good as can be within the code, and the ego correction is just that subtle extra compensation to get the idle AFR's perfect.
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Old 08-10-2012, 09:25 PM   #6
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Could you post your EGO settings please, cym? You may have stumbled upon something that I have not been able to duplicate, and I would love to see what you came up with.
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Old 08-10-2012, 09:47 PM   #7
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I'm running an LC-1, and I changed the Active Above RPM to 800 (from 1400) for ego. I may have also changed the AFR target rpms a little..can't recall. Here's the tables I run now and haven't touched for a long time now.
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Continually leaner AFRs-afr.jpg   Continually leaner AFRs-cltait.jpg   Continually leaner AFRs-ego.jpg  
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Old 08-10-2012, 09:48 PM   #8
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Thanks Cym! However, could I get your EGO control specifically? I mean, are you using the PID setting, or just the simple algorithm?
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Old 08-10-2012, 09:52 PM   #9
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That's basically it. My baseline temperature when tuning was right around 70*F.

I've added the EGO to the post above.
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Old 08-10-2012, 09:58 PM   #10
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Ahh, you are using the simple (non-PID) algorithm. Thanks Cym!
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