Basic Progression for Incorporating AFR

[DonMaximo]

I use a MegaSquirt PNP for the Mustang 5.0

The Base tune General Settings are set to: don't include AFRtarget.

Naturally, I moved forward with Warm tuning and then Cold Start up which is where I'm at now.

Before I get into Enrichment, I was wondering "IF" this is the time I should make the General Settings change to: "include AFRtarget"

Or should I wait to have Enrichment completed before converting over to the AFR table for future tuning.

Thank you in advance.

-D

[elaw]

I'd say with regard to warmup enrichment, it really doesn't matter.

The best time to make the change is before you start tuning at all, but of course that ship has already sailed!

The problem is, now that you've tuned with "incorporate AFR" turned off, your AFR targets have been included in the VE table. So in order to make the change, you have to back out the AFR target from each cell in the VE table.

What that basically means is that for each VE value, you have to compute the ratio of target AFR to stoichiometric, then multiply the VE value by that ratio. For example: suppose at some particular load and RPM your target AFR is 12(:1), and the VE table value is 150. If you're running gasoline for fuel your stoichiometric AFR is 14.7. So first compute the target-to-stoichiometric ratio as (12/14.7) = 0.816. Then multiply the VE number by that ratio, so 150 becomes (150 * 0.816) or 122.5. Plug that number into your VE table.

You have to do that for each cell in your VE table with one exception that should save you some time. For cells where the target AFR equals stoichiometric, the ratio of target to stoichiometric is of course 1.0. So those cells can remain unchanged.

Once you've done the above, turn on "incorporate AFR target" and enter the correct values in the AFR target table.

[DonMaximo]

I followed the instructions and the conversion to Incorporate AFR seems to be working seamlessly. I am a Happy Camper.

Regarding the Autotune feature of TS, I used to LOCK-OUT the VE cells in my Idle zone. Now that I am incorporating AFR, should I remove those locks so that Autotune can modify my Idle-VE values ???

[elaw]

That's a tough call... sometimes autotune works for idle, sometimes it does not.

My suggestion would be save your tune, and then try to autotune. If it makes things better, keep the tune. Otherwise revert to the saved one and tune the idle area manually.

[Marek]

I made and posted a spreadsheet a while back to check calculations. To calculate pulsewidths, part of it reexpressed the AFR table as a 16x16 table with the load and rpm axes being user settable. I assume I must have since deleted it from the forum to save space. If you want a copy, pm me.
You can obviousaly use it to change your VE table to either include or not include AFR into the numbers.

kind regards
Marek

[acedeuce802]

Quick question about using incorporating AFR. Does MegaLogViewer know when this is enabled? This would be a concern when using the fuel table modifier in MLV. MLV would need to know if the VE map is supposed to correlate to the AFR map, or correlate to a stoich map.

[LT401Vette]

Quick question about using incorporating AFR. Does MegaLogViewer know when this is enabled? This would be a concern when using the fuel table modifier in MLV. MLV would need to know if the VE map is supposed to correlate to the AFR map, or correlate to a stoich map.

It doesn't matter... While adjusting the VE table to achieve the target AFR's you still need to adjust the VE Table up and down... The key with having it on is that now if you change your target AFR's later, you do not need to adjust your VE table to for the fueling to target the new AFR's.