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Standalones That You Would Never Use 
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QFP80 - Contributor

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I'm going to ask this here....just because.
It was noted to me (non tuner) that some ecu's fuel by VE, and some use fuel mass, as far as I'm concerned as long as it gets the job done effectively I don't care either way, but- I can't really find much info on the fuel mass explanation, I have a dim understanding of VE.


Wed Mar 28, 2018 3:41 pm
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If you meant air mass, then okay.

FreeEMS fuels by speed density (for real, not a joke) which includes VE and fuel mass

It can also fuel by Alpha-N which still includes fuel mass, but you control it somewhat directly in relation to assumption of air flow based on throttle position

MAF / AFM = measuring the mass of air entering the engine and supplying appropriate fuel mass to go with that - likely what you meant.

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Wed Mar 28, 2018 8:24 pm
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QFP80 - Contributor

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This is part of an email from the local guy.

I believe any will do what you need. The LCP4 and Pro48 are both very feature rich. The LCP4 is fuel mass injection based tables, the ProEFI is VE. There is some cost savings to the LCP4 - about $200cad in hardware. In terms of setup, we have more familiarity with ProEFI, so if we are doing all of the setup, there may be some cost savings in the time spent. If you are doing the basic setup and we are tuning, the difference will likely be small.

Speed density to me is MAP/TPS trim with O2.
AlphaN is programmed, no sensor input except TPS.
I thought MAF would be fuel mass, but Baldur says it is a pain to tune- so I assumed he prefers MAP...which leads me to speed density. BaldurFor most applications I do not recommend a MAF, they are more difficult to tune than a speed density system.

Baldur It can be configured to behave like a VE model, but the fuelling is based on fuel mass, which is kind of novel.
I have plans to add a full air flow model with VE just to better support mass air flow sensors.


Maybe I'm just confusing terms.


Wed Mar 28, 2018 10:49 pm
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Weird. That's how Alpha-N is implemented in FreeEMS IIRC. Or similar (fuel mass).

Alpha-N still has other inputs, in particular, all models require coolant and air temperature to properly control an engine. In FreeEMS air temperature is not fully leveraged yet, but it is used in some ways.

Speed density is as the name implies, true speed density requires an integral lambda "setting", a VE, a manifold pressure from which you can infer cylinder fill, and air temperature to know the density of that fill. The speed part of the name just implies that things are different at different engine speeds, which is true. They're also different at different manifold pressures, which is also true.

Alpha-N skips the VE part supplying fuel directly to the outputs based on TPS and engine speed. How you implement beyond that basic definition is up to you as an ECU developer.

Fuel mass controlled by MAP skips the VE, too, so it's not really speed density at all. It's equivalent to a PW table if you assume fixed fuel temperature and therefore density and stable rail pressure, etc.

I guess that adds Baldur's ECUs to my "wouldn't run" category as to me properly modeling the engine's airflow is fundamental to other axes of control. But each to their own. Many systems styles will work just fine if setup right.

I'll probably split these 4 posts (and any subsequent) off to a dedicated thread as they don't really belong here. But not today.

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FreeEMS dev diary and its comments thread and my turbo truck!
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Thu Mar 29, 2018 6:02 am
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Fred wrote:
Fuel mass controlled by MAP skips the VE, too, so it's not really speed density at all. It's equivalent to a PW table if you assume fixed fuel temperature and therefore density and stable rail pressure, etc.

I guess that adds Baldur's ECUs to my "wouldn't run" category as to me properly modeling the engine's airflow is fundamental to other axes of control. But each to their own. Many systems styles will work just fine if setup right.

I'll probably split these 4 posts (and any subsequent) off to a dedicated thread as they don't really belong here. But not today.

It makes it easier to setup the fuel table as the fueling holds to a linear slope if you use it with a modifier for lambda control.


Thu Mar 29, 2018 7:45 pm
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I was using Link G4 storm (dark blue label with built in 3 bar map sensor) for 3 years in toyota glanza 4efte(coil on plug set up).
The ecu was stable , it was working in different altitudes with no problems on boost , only at cruising had a slightly poor mix.
The only think that i didn't like was the baro correction when it was turned on the car was like a turtle..


Mon Apr 30, 2018 6:14 pm
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