VE vs AFR table - Best practice for fuel tuning

[galingong]

As I'm new to MS I'd like to check if I understand the concept and do things right.

Is it correct to turn off "Incorporate AFRTarget" and EGO control, tune the VE table for ~14,7 across the range and THEN turn on "Incroporate AFRTarget" and use that to make the mixture more lean/rich at individual circumstances?

I also don't clearly understand the difference between "Incorporate AFRTarget" and EGO control. Is it right that EGO control is for minor correction whereas including AFR target table should adjust your mixture completely according to the AFR table settings?

I'd also like to check if my AFR table is sound(2.000 cc N/A engine, SOHC - 8 Valves):



+1: My stock tach gauge reads wrong. I'm using the tacho output, if I set it's speed to normal, it still shows ~2/3 of real rev. From factory it was a dizzy + coil setup with TFI, now it's MS driving a coil pack (number of coils set to wasted spark, sync from crank VR).

Thank you, cheers!

[pit_celica]

I would do it this way :

- use a good AFR target map (yours seems fine)
- incorporate AFR target
- tune VE table with autotune feature.
- then, if you want to enrich/lean a part of the fuel table (during a dyno tuning session by example), then do not touch the VE table, only change the AFR target and the fuel should change accordingly because the AFR target is included in the fuel equation.

I do not suggest to tune for 14.7 AFR for the whole range as this isn't good at high load/high RPM. This can be bad for the engine.

The main difference when "Incorporate AFR target" is shown in the equations in this page of the manual : http://www.msextra.com/doc/pdf/html/Meg ... p-1.4.html (see section 7.2)

EGO control is a closed-loop that make changes to the fueling (through the GEGO parameter) based on the difference between the actual AFR reading and the AFR target. "Incorporate AFR target" has nothing to do with the AFR sensor. It's only there to keep tuning easier because if you do not use it, if you want to enrich or lean a portion of the fuel table, you need to change the AFR table (so that EGO control can target the new enriched/leaned target) and you also need to change the VE table to obtain this new AFR (to actually change the fuel equation output).

Really easier to use "Incorporate AFR target".

Sam

[galingong]

OK, thank you, now it makes sense. Until now I've got it wrong. My impression was that the enabled "Inc. AFRTarget" setting took the actual AFR reading into account, and modified fuel amount based on the target. So that doesn't happen, and actually EGO control does that.

[benckj]

This was a good read as I also thought the AFR incorporated target used the O2 wideband for adjustment. I should check my setting to ensure the EGO control is enabled (mental note taken).

I guess both functions should be enabled for real time adjustment to the AFR table and what is actually being measured by O2? I noted during some tuning runs the VE table was very slow to respond which may be related to the resolution or steps allowed for adjustment (% of VE )?

jim

[galingong]

Yes, I've enabled both - EGO control for real time fuel adjustment based on current measured AFR. Based on response above, including the AFR target in the equation is just an auxiliary table for you to be able to work with more "real world" values, and also for auto-tuning.