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Old 01-20-2009, 10:26 PM   #1
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Default Enabling AFR Target Tables

I know this is going to be beyond simple to most of you guys, but I just can't find it. I'm trying to enable AutoTune on my MS PNP. I've wired up the wideband. I'm trying to follow along with the manual:

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...you can make MegaSquirt target a lean air-fuel ratio while cruising, and go to a rich air-fuel ratio under boost and have the oxygen sensor help you target both. To enable this, select Lambda AFR Settings from the More Settings menu, and turn on the 8 x 8 AFR target table for VE Table 1. Once this is on, you can go to the AFR target table and set your targets as a function of manifold pressure or boost and RPM. The values in this target table will be the raw voltage output from the oxygen sensor controller, not actual air-fuel ratios.

MegaTune is also able to tune the VE tables on its own, based on inputs from a wideband sensor. This feature is called AutoTune. The software will adjust the VE tables in a limited range to make the air-fuel ratio match your target settings. Use this feature with caution and make sure your targets and sensor readings are correct before you enable it. You will usually still need to do fine tuning by hand. You should not rely entirely on AutoTune mode to get your car in tune.
First of all I'm having trouble understanding the difference between the voltage targeting and the AFR targeting. Secondly, I was able to activate the voltage "AFR Targets for VE Table 1 (Volts)", but I can't find the map for AFR. Are these tables trying to accomplish the same goal, just in a different terminology? If that is the case how do you convert it to AFR? If that's not the case I'd appreciate it if someone could differentiate between the 2 and let me know how to get to the AFR tables.

Be gentile with me, just got the car cranked yesterday and this is my first real day playing with the megasquirt.
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Old 01-20-2009, 10:40 PM   #2
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Your AFR table is in AFR or volts. The table is under "More Settings". It's labeled "AFR targets for VE table 1". I assume your wideband is an AEM if you're seeing volts. Here's how to change that: https://www.miataturbo.net/forum/t28005/ Autotune does not work too well from what I've heard. It's better to take a log (under "File", "Datalogging", "Record") and analyze it with Megalogviewer then export the changed VE table and import it to your MSQ. Read up on the recent threads here about appropriate AFR tables because if you're not using a good one any tuning is bunk.

Last edited by johndoe; 01-20-2009 at 10:59 PM.
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Old 01-20-2009, 10:44 PM   #3
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any more info on the quality of autotune?
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Old 01-20-2009, 10:48 PM   #4
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Ahh, thank you so much. I knew it was something stupid, and yes, I do have an AEM wideband.
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Old 01-21-2009, 11:20 AM   #5
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I have had good success with the autotune. I did a 45 minute run in almost all the rpm ranges, in boost out of boost and it worked well. The VE tables need to be tuned pretty good though. The autotune isn't a cure-all. Do a search for ARF tables and formulate your own table based on what other people are running. Do not use someone else's AFR tables for your car.

As for the fix for the Volts to AFR in Megatune. I followed Joe's instructions to make the change, but I could not get it to work in Vista. I even followed Brain's instructions on how to work around Vista's system, but it would not change. I was able to make the change work in XP without issue. I am stuck with Volts.
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Old 01-21-2009, 11:42 AM   #6
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Quote:
Originally Posted by 96rdstr View Post
Do not use someone else's AFR tables for your car.
I disagree. You can use someone elses table as long as it's sane. You may want to change any table though depending on your driving habits.
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Old 01-21-2009, 03:15 PM   #7
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Quote:
Originally Posted by johndoe View Post
I disagree. You can use someone elses table as long as it's sane. You may want to change any table though depending on your driving habits.
I disagree with your disagree. So we might have to agree to disagree....or something like that.

Someone's car may run fine at XX.X AFR someone else may get ping at XX.X AFR. Owning to different conditions and no two cars will operate the same, I would go richer than need be and then lean it out as I tune the car.

I use other peoples AFR tables, VE tables, and Spark tables as guide lines and comparison purposes only.
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Old 01-21-2009, 03:28 PM   #8
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As a general rule, AFR tables are a safer to share than spark or VE tables, but you will definitely want to give it a sanity check before using it.
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