How does the ECU Master EMU use VE values?

[diracdeltafunct]

Having read parts of "Engine Management Advanced Tuning" (Greg Banish) and parts of the MegaSquirt documentation I have some questions about VE tables and how the ECU Master EMU deals with them. Please correct any mistakes in my reasoning.

Also, please tell me how to enable TeX-style equations so that my equations are more friendly, I've tried [tex], [latex] and [math]. I will then edit my post, unless a nice administrator wants to do it for me.

This is all in the context of speed density. Where is matters, assume the 3S-GTE engine is the engine we are working with.

We have that M = V_{engine} \cdot p_{air} \cdot \dfrac{\mbox{RPM}}{2}, where M is the theoretical airflow rate of the engine in its naturally aspirated form. V is the volume of the engine, p is the density of the air.

VE is defined as VE = \dfrac{\mbox{Actual instantaneous mass flow at RPM and MAP}{M}, where MAP is the intake manifold pressure.

Is this the same way VE is defined in the ECU Master EMU? Or is it defined differently?

If VE is defined in this way, then increasing the VE in some arbitrary cell does not increase the fuel directly. What it does is simply tell the ECU that the flow rate is a certain value, for a given RPM and MAP value. By increasing this value (given that everything else stays the same), the ECU would in turn calculate that more fuel is needed to meet this new volume of air. Is this how the ECU does it? Or does it use a different procedure?

Then, we have the calculation for how much fuel to deliver: Fuel F = \dfrac{\mbox{Actual mass air flow}}{AFR \cdot 120 \cdot \mbox{RPM}}

Finally when the ECU is ready to call its procedure to actually deliver fuel, it can use the equation F = \dfrac{\mbox{Injector flow rate} \cdot \mbox{Duty Cycle} \cdot 120}{\mbox{RPM}} and solve for Duty Cycle to determine how much to pulse the injector.

Is this how the ECU Master EMU does it? Even with EGO feedback turned off?

It doesn't seem to me that this is the procedure the ECU Master EMU uses. Because when I have EGO feedback turned off and change the AFR table in real-time (even increasing or decreasing the whole table at once), I don't see any change on the wideband lambda. If AFR is fixed when EGO feedback is turned off, then from where does the ECU get this constant value? The ECU doesn't know what fuel I'm using, so it cannot use a stoichiometric constant, unless it just uses a very general one.

[Wuniek]

Did you have opportunity to look at EMU manual ? http://ecumaster.com/pobierz/emu/emu_manual.pdf

I think you will find there answers to your questions...

[diracdeltafunct]

Did you have opportunity to look at EMU manual ? http://ecumaster.com/pobierz/emu/emu_manual.pdf

I think you will find there answers to your questions...

PW.jpg

I don't think it describes anything except how the pulse width is derived.

[Wuniek]

I don't think it describes anything except how the pulse width is derived.

for me it was good lecture before sleep for few days, in my felling all is there (how strategy works, how correction impact calculation and so on)
but i think you want more essential knowledge

[diracdeltafunct]

How does the ECU arrive at the constant INJ_CONST? How does it know what is lambda = 1 when it doesn't know what fuel is being used and therefore neither knows what a stoichiometric mixture ratio should be?

Note that I'm not saying the ECU does anything wrong. I'm just asking how does it do it.

[Jan32]

Lambda 1 is on every fuel type Lambda 1 the AFR changed.
And you can choose the type of fuel in oxygen sensor parameters.

Here you can see the advanced fuel model viewtopic.php?f=12&t=400

[RHD]

There are 2 different fueling strategies available. Basic lamda/afr mode where the fuel delivered is a calculated injector puls width or the Advanced Lamda mode (later FW test versions only) where the target lamda and charge temp tables are used in the fueling calculation, this is more of a true Volumetric Efficiency type calculation using engine efficiency (VE) and air mass from which the correct fuel dose is then calculated to achieve the lamda target.... In advanced lamda mode changing the target table will alter the actual AFR

[Jadzwin]

In general you need to choose Advance fueling mode with Lambda target. Lambda is independent of the fuel you are using (1 is always stoichiometric).
In Advance mode the change in lambda target automatically change the fuel flow.

[diracdeltafunct]

In general you need to choose Advance fueling mode with Lambda target. Lambda is independent of the fuel you are using (1 is always stoichiometric).
In Advance mode the change in lambda target automatically change the fuel flow.

Still, it is not clear to me what Lambda is in normal fueling mode (not advanced). How does it arrive at the AFR value behind the constant Lambda?

Also, I'm still wondering how the VE table is used.

Edit: Actually maybe this is not that important. I will just use the new advanced mode instead. But is there a stable version of the client and firmware that includes the advanced mode? I would rather prefer to be running a stable version.

[Jadzwin]

Please use 1.133 version. We are about to launch new official version based on this version.
In standard mode the AFR table is just used for Lambda correction as a target.