# Modelled fuel equation

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Hi,

I began to play a bit with the new 5.2.2 firmware and with the modelled fuel equation mode. I am running sequential / staged fuel mode and the primary injector are rated 1200cc @ 3 bar and secondary injectors are 1000cc @ 3 bar. Secondary injectors starts to inject fuel on a condition when TP exceeds 30%.

Now a few question: under the injector set up you have to put in the injector flow at rated pressure. If you use staged injection, is this the total flow of injectors, 2200cc in my case? The ecu is then able to calculate the required fuel also at the lower load when only the primary injectors are on use (i.e. under 30% in my case)? And does the injector rated fuel pressure mean measured pressure or absolute pressure? I suppose measured pressure as the injector manufacturers states the pressure, "3 BAR" -> 400 kpa in absolute.

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Hi Sutkale,

Very good question,

can you please post your PCL file you are currently playing with 5.2.2

It makes things a little quicker.

So you have selected sequential/ staged as injection mode and modelled as your fuel equation mode is this correct.

If you post your PCL will take screen shots and explain the best I can.

I am under the impression that the injector flow @ rated pressure is per injector, especially considering you are running staged injection.

So this value should be the true given flow rate of a single injector at the used fuel pressure, EG from memory an ID 1000 is actually 1015 cc at 3 bar.

Regards

Dave.

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Hi Sutkale,

Very good question,

can you please post your PCL file you are currently playing with 5.2.2

It makes things a little quicker.

So you have selected sequential/ staged as injection mode and modelled as your fuel equation mode is this correct.

If you post your PCL will take screen shots and explain the best I can.

I am under the impression that the injector flow @ rated pressure is per injector, especially considering you are running staged injection.

So this value should be the true given flow rate of a single injector at the used fuel pressure, EG from memory an ID 1000 is actually 1015 cc at 3 bar.

Regards

Dave.

Hi Dave,

Yes, modelled is the fuel equation and fuel mode sequential / staged. HavenÂ´t run it in real life yet, just preparing it currently.

It seems IÂ´ve got a bad deal with the forum since it does not let me attach files "The extension pclr is not allowed" this time.. :twisted: IÂ´ll put some mail to you.

EDIT: file is in your email Dave!

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Put this into a real world test. The engine started nicely at 0 celsius ambient and had rather good warm up with 0,87- 0,9 lambda at idle. Once engine reached about 40 degrees, lambda dropped to 0,78 - 0,82. Pretty much nothing helped the fueling to reach 1,0 lambda at idle. Charge temp was 100 % relying on ECT. Every set up should be right but the fuel temperature sensor is missing and I cannot verify the true flow rates of the injectors. Maybe the lack of fuel temp sensor causes this? Only changing the size of injectors under injector set up (2200 - 1200) had an effect on fueling causing even more fatter fueling..

Funny that the injector actual PW stayed almost steady at 2,5ms and nothing at the setups made this change (exept the change in injector size). I know the engine needs 2,0 ms to reach lambda 1 at gasoline.

Just training with this nothing serious yet.

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Hi,

SPECIAL NOTE """"ALL INJECTOR DATA MUST BE ACURATE FOR THIS TO WORK CORRECTLY."""

Regards

Dave.

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Hi ,

the fuel temp input is very important, however not a necessity, from memory.

Quickly looking at the PCL file you sent me the sec/pri ratio calculation you have made is correct, however are you 100% sure these are the true flow rates for these injectors at 3 bar.

What are the actual injectors, brand etc,

DEAD TIMES ETC are very very important in this type of setup.

You also mention about the warm up being fairly good until 40 deg C, you also state that you are using the Charge Estimate table for your warm up and it is setup for 100 % biasing to the ECT.

However I see the Charge Estimate table set up as MGP vs RPM, no reference to ECT at all.

Your WARM UP ENRICHMENT table is at 0, no influence, but is on.

IAT correction is turned off, no influence.

You are running what I would consider very strange Injector timing angles especially at 500 rpm to 1000 rpm zones.

400 deg at 500 rpm and then 290 deg at 1000 rpm.

There will be some wild interpolation from 500 to 1000 rpm as far as injection timing goes, not to say this isn't correct for your setup, however on a new setup I would be going for more consistent and basic (realistic default) numbers in the table until you can tune these value/table correctly on the dyno.

I have only had a ten minute look so far and the above are my observations so far.

Regards

Dave.

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Hi ,

the fuel temp input is very important, however not a necessity, from memory.

Quickly looking at the PCL file you sent me the sec/pri ratio calculation you have made is correct, however are you 100% sure these are the true flow rates for these injectors at 3 bar.

What are the actual injectors, brand etc,

DEAD TIMES ETC are very very important in this type of setup.

You also mention about the warm up being fairly good until 40 deg C, you also state that you are using the Charge Estimate table for your warm up and it is setup for 100 % biasing to the ECT.

However I see the Charge Estimate table set up as MGP vs RPM, no reference to ECT at all.

Your WARM UP ENRICHMENT table is at 0, no influence, but is on.

IAT correction is turned off, no influence.

You are running what I would consider very strange Injector timing angles especially at 500 rpm to 1000 rpm zones.

400 deg at 500 rpm and then 290 deg at 1000 rpm.

There will be some wild interpolation from 500 to 1000 rpm as far as injection timing goes, not to say this isn't correct for your setup, however on a new setup I would be going for more consistent and basic (realistic default) numbers in the table until you can tune these value/table correctly on the dyno.

I have only had a ten minute look so far and the above are my observations so far.

Regards

Dave.

Hi Dave,

I know one should know the true flow rates of the injectors when using modelled fueling equation. These are some Bosch EV14 injectors purchased from Fiveomotorsports. I will get these measured and get the actual flow rates and dead times later on.

Regarding the Charge Temp Approximation, the axis setup is locked to MGP, at least on my case..? Are you Dave able change it in your software?

The injector timing is not subject to interpolation on idle, since the idle rpm is around 1200 and the timing is 290 from 1000 to 1500 rmps. However, I will have a closer thought upon that.

I noticed that short pulse width adder table had 0,406 as default value and zeroing that actually put the lambda close to 1 at idle when I did a short test.

This was only a short test and will take this mode on use whit the new set up. Very interesting indeed...

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Hi Sutkale,

you are tackling this correctly, small steps and asking questions, best way to make the transition.

I am clarifying a few things with Scott right now regarding your setup.

Regards

Dave.

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Guys,

One thing (beside the numerous other ones) came to my mind also. What does the fuel table numbers represent in this new mode? Are they still multiplayers like in the tradional fuel mode? Is there any calculation method available for the public or is this proprieatary info? This would make me understand better how the ECU determines the actual injector pulsewidth in real conditions.

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The numbers now used in the fuel tables represent volumetric efficiency . It is now VE based.

Simplified this meens that if your 2 liter engine ingests 1 liter at a particular cell in your map you would have a number of 50 in that cell, as it ingests 50% of the potensial volume. This would be in a low load situation of your map. If you have a natural aspirated engine and open the throttle wide open on high revs you would theoreticaly be at around 100 in the cell.

Now all of this of course depends on how good your engine actually breaths, and the fuel map will give you the answer of that when its fully tuned.

Edit. Removed a part so that it doesnt confuse anyone..

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Hi,

Just so everyone is aware, 150 is the highest fuel cell value available to enter in the VE table.

Regards

Dave

P.S Thanks STEVE.

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Hi Sutkale,

If you use the help file there is a lot of info and a block diagram on how each of the fuel equations work and the calculations are derived.

Regards

Dave.

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SPECIAL NOTE TO EVERYBODY,

IT IS VERY IMPORTANT THAT YOU ALL READ THE FIRMWARE UPGRADE NOTES THAT ARE DISPLAYED WHEN A NEW VERSION IS RELEASED.

Not only does it tell you about the changes and any fixes, it tells you how these changes work.

The HELP file also gives you special instruction tips to look out for etc, EG:: like in version xxxx.123 make sure that this table value is set to 0.

Not enough people read these information which is right at hand.

I use it often.

This is not directed at anyone, it is directed at EVERYBODY.

Regards

Dave.

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Engine is currently in pieces at the garage floor, so it is time to do some virtual tuning..

Has anyone have time to think how the modelled fuel equation works with staged injection? I particularly have paid attention to injector set up and do not know how to put the settings in the following situation; under injector set up one should put down the true flow rates of the injectors at given pressure (3.0 bar I assume). If you are running staged injection, is the injector flow rate number a total number of injector flow? Given you have primaries 1200 cc and secondaries 2300cc, is the flow rate number 3500cc (each cylinder is sprayed with 1200cc + 2300cc injector)? Should the secondaries start to spray when TPS exceed 30 %, is the ECU capable of calculate the right opening time when only 1200ccÂ´s are spraying when TPS is under 30 %.

One thing that I noticed is that the software do not accept bigger injectors than 3000cc. In that case and provided that total flow of injectors is more than 3000cc, does the modelled fuel equation work at all? I am gonna play with methanol so big injectors are needed in 4 cyl engine.

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Hi Sutkale,

can you post your PCL file and I will help set it up , take screen shots and post on the forum with explanations .

This way everyone can learn.

It is easier for me to do in this fashion.

Regards

Dave.

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Hi Sutkale,

can you post your PCL file and I will help set it up , take screen shots and post on the forum with explanations .

This way everyone can learn.

It is easier for me to do in this fashion.

Regards

Dave.

I am currently on holiday trip, can do later this week.

Edit: actually I emailed that to you on late October..?

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Hi Sutkale,

have a great holiday, I will look for your PCL file, I have hundreds and hundreds of PCL files.

I just have to remember what I have saved it as.

Just to clarify, you wish to run Sequential / Staged Multi Fuel (METHANOL) eventually correct.

As the multi fuel Equation will have a big impact on the importance of the PCL setup.

Do you remember what you called your PCL, will just help me find it.

IS IT VOLVO - BENSA

Regards

Dave.

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Hi Sutkale,

have a great holiday, I will look for your PCL file, I have hundreds and hundreds of PCL files.

I just have to remember what I have saved it as.

Just to clarify, you wish to run Sequential / Staged Multi Fuel (METHANOL) eventually correct.

As the multi fuel Equation will have a big impact on the importance of the PCL setup.

Do you remember what you called your PCL, will just help me find it.

IS IT VOLVO - BENSA

Regards

Dave.

Hi DAve,

Yes thatÂ´s it... But that is for my gasoline set up, but doesnÂ´t change things in this respect.

Yes, sequential / staged modelled fuel equation.

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Cool,

the PCL is the one I need.

Now I just want to confirm the intent to use Methanol also at some stage as this will be classed as a DUAL FUEL SEQUENTIAL /STAGED MODEL.

Regards

Dave.

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I forgot the whole thing. So is there any chance to get the modelled fuel equation into operation if youÂ´re running staged injection and the injector size exceeds 3000cc in total (modelled fuel equation accepts 3000cc as maximum)? In my case running primaries as 1200cc and secondaries 2300cc, resulting 3500cc. Running E85 and methanol in app. 1000 horses 4 cyl engine. Running on E85 smaller injectors would do, but on straight methanol even 3500ccÂ´s are on their limits.

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Good day,

Just out of curiosity would you be willing to share any fuel pressure data? For example, what differential pressure are you working with and do you have an estimate of what peak fuel pressure do you expect the injectors to see? In addition, what's the displacement of your engine?

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Good day,

Just out of curiosity would you be willing to share any fuel pressure data? For example, what differential pressure are you working with and do you have an estimate of what peak fuel pressure do you expect the injectors to see? In addition, what's the displacement of your engine?

Hello,

Base fuel pressure is 400kpa absolute and running 1:1 fuel pressure regulator. Max boost would be around 450kpa absolute, so we're seeing 850kpa peak fuel pressure at 450kpa boost? Engine displacement is 1998cc.

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Thanks for the response.

I'm terribly curious about fuel systems now that fuel injector data (as well as the manner in which a modern ECU is able to exploit this) has become readily available with great detail. Thanks again for sharing.

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