N54 Stock DME Flex Fuel

[dyezak]

How would you account for a secondary fuel injection control mechanism in the DME? It will be neat to see if/how this works with those running PI, but I'd be a bit apprehensive unless they have some way to modify the PI controller as well.

Since we are talking about PI or a double barrel HPFP the only thing we are concerned with is the interpolation on fuel. All the other interpolation values that flex fuel brings to the table are generally not concerning to us in this conversation (generally). As a general rule of thumb gasoline has 30% more energy density than ethanol. So your fueling scalers are almost always in the neighborhood of 1.0 for gas and 1.29-1.31 for ethanol. If you are switching from gas to ethanol to get you in the right ballpark you add 30% fuel.

PI and Double Barrels are set up with a static map. You could certainly have a gasoline map, and add 30% to that and get a decent ethanol map. But you don't need to. You can split the difference and sit your PI/Double Barrel at 15% more fuel than gas.

What does that mean to the DME tune? Means for your gasoline portion you will need to retune to reduce fueling. For your ethanol portion you'll need to retune to increase fueling. Then you let your DME interpolate the fueling values in your new tune where your AIC is essentially splitting the difference and never changing...but the DME is changing everything on its end.

Conceptually not difficult....but in practice it might take tuners a bit of time to get themselves some base maps setup for this type of scenario. Probably add another layer of charges/fees to account for this. But technically it's no problem.

 

[ninjacoupe]

I may never use this as E85 is all over where I live but I’ll buy it anyways lol. Now how about some two step logic!

 

[Abacus38]

Since we are talking about PI or a double barrel HPFP the only thing we are concerned with is the interpolation on fuel. All the other interpolation values that flex fuel brings to the table are generally not concerning to us in this conversation (generally). As a general rule of thumb gasoline has 30% more energy density than ethanol. So your fueling scalers are almost always in the neighborhood of 1.0 for gas and 1.29-1.31 for ethanol. If you are switching from gas to ethanol to get you in the right ballpark you add 30% fuel.

PI and Double Barrels are set up with a static map. You could certainly have a gasoline map, and add 30% to that and get a decent ethanol map. But you don't need to. You can split the difference and sit your PI/Double Barrel at 15% more fuel than gas.

What does that mean to the DME tune? Means for your gasoline portion you will need to retune to reduce fueling. For your ethanol portion you'll need to retune to increase fueling. Then you let your DME interpolate the fueling values in your new tune where your AIC is essentially splitting the difference and never changing...but the DME is changing everything on its end.

Conceptually not difficult....but in practice it might take tuners a bit of time to get themselves some base maps setup for this type of scenario. Probably add another layer of charges/fees to account for this. But technically it's no problem.

Since we are talking about PI or a double barrel HPFP the only thing we are concerned with is the interpolation on fuel. All the other interpolation values that flex fuel brings to the table are generally not concerning to us in this conversation (generally). As a general rule of thumb gasoline has 30% more energy density than ethanol. So your fueling scalers are almost always in the neighborhood of 1.0 for gas and 1.29-1.31 for ethanol. If you are switching from gas to ethanol to get you in the right ballpark you add 30% fuel.

PI and Double Barrels are set up with a static map. You could certainly have a gasoline map, and add 30% to that and get a decent ethanol map. But you don't need to. You can split the difference and sit your PI/Double Barrel at 15% more fuel than gas.

What does that mean to the DME tune? Means for your gasoline portion you will need to retune to reduce fueling. For your ethanol portion you'll need to retune to increase fueling. Then you let your DME interpolate the fueling values in your new tune where your AIC is essentially splitting the difference and never changing...but the DME is changing everything on its end.

Conceptually not difficult....but in practice it might take tuners a bit of time to get themselves some base maps setup for this type of scenario. Probably add another layer of charges/fees to account for this. But technically it's no problem.

my main concern was more so the high level build but then again they would be using syvecs and this would be a non issue

 

[LamboLover]

To my understanding, injector pulse, ignoring closed loop feedback, temperature compensations and opening times, is proportional to:
calculated air mass per cylinder
fuel scaler

... and inversely proportional to:
target lambda
root of fuel pressure relative to a standard value

For flex fuel, whilst the target lambda is blended, the fuel scaler will be where the business is of compensating for stoichiometry is.

Upgraded DI fuel systems should be a black box from this point of view, yes with their own control requirements, but I couldn't see the need for any special treatment for flex fuel just like other platforms don't need it.

For PI, so many of the variables are external and in different time domains electronically and physically, and the controllers except Syvecs do not IMHO remotely address a fraction of the issues, I'd prefer DI.

 

[Jake@MHD]

The ECA I developed will support PI scaling. Basically, you start by tuning your AIC map for full E85. The ECA has another input and output (in addition to sending Ethanol % to the DME), which takes in TMAP signal, and outputs a scaled version based on Ethanol %. You will use this as the input to the AIC. Therefore when you are running say pump gas, the AIC will be seeing a lower boost value and trace a column in the AIC map of injecting less fuel. We spent a lot of time tweaking this scaled calculation and it works very well with a "set and forget" map in the AIC. The remainder can be easily cleaned up with the interpolation between pump and E85 fuel scalar maps. If for some reason you don't want to scale the signal to the AIC, you may need to go under 1.0 on the values in your pump scalar map and it'll be using PI for a higher % of total fuel than needed.

I will talk the Chris and confirm, but I believe an appropriate AIC basemap will be provided with ECA purchase.

DI only whether with one or two HPFP will work fine as the DME just sorts that out.

 

[Tuningservice.no]

So no need at all for a splitsecond controller to activate the secondary fuelpump in the VTT Double Barrel system?

Should it just be run constantly like the first pump?

 

[Jake@MHD]

So no need at all for a splitsecond controller to activate the secondary fuelpump in the VTT Double Barrel system?

Should it just be run constantly like the first pump?

You will still need the AIC to control a second hpfp (for now), but will not require the scaling from the ECA as the DME can adjust the main hpfp however it needs.

 

[ninjacoupe]

Sounds like this is going to be pretty user/tuner freindly. Love the improvements MHD keep them coming!

 

[Omar@VaderSolutions]

Sounds like this is going to be pretty user/tuber freindly. Love the improvements MHD keep them coming!

tuber

 

[Cheezy]

tuber

I thought he meant youtuber and of course you came to the party.

 

[ninjacoupe]

Lmao I meant to type tuner. Edited it

 

[Tuningservice.no]

I thought he meant youtuber and of course you came to the party.

Redtuber

 

[doublespaces]

I will talk the Chris and confirm, but I believe an appropriate AIC basemap will be provided with ECA purchase.

Will this map be available to download and unlocked to send to our tuner of choice?

 

[fmorelli]

Will this map be available to download and unlocked to send to our tuner of choice?

Hmmm, I'd like to understand how this would even work? As I understand it, the flex fuel DME implementation requires software algorithm changes, not tuning table changes, with the addition of ECA sensor data, which the algorithm employs. I would imagine tuning is a separate thing, not to mention a pre-cooked solution gives no control over the tuning characteristics against mods and local conditions. Am I missing something?

Ideally, maybe, a tuner could tune at a target (say, E50), and the flexfuel impl will augment DME outputs based on ethanol variance. But hey that's my hallucination ... what's the real answer?

Filippo

 

[Jake@MHD]

Will this map be available to download and unlocked to send to our tuner of choice?

I think I will arrange the AIC map to be emailed to a user after ECA purchase or something like that. You can't lock an AIC fuel map, so yes it will be able to be sent to whoever you like to tweak it to your car if necessary.

On the actual DME bin side, all of the new FlexFuel xdf's will be added to the github with the suffix _FF (ex, IJE0S_FF.xdf) These new XDF must be used if doing a flex fuel tune as certain table size changes, additions, restructure, moving were done. Non-FF tunes will continue to use the traditional XDF. New table additions will be maintained to both versions, perhaps forever or until a more elegant solution is worked out.

Also being added to the github is a simple exe tool that performs all of the calibration formatting detailed above, and outputs a bin ready to use with the FF XDF. This is a required step or you will see some crazy junk in the FF tables The logic to make it all work is then added at flash time via MHD.

 

[mang.vang]

Will this require custom maps or will there be some sort of ots maps?

 

[Jake@MHD]

Will this require custom maps or will there be some sort of ots maps?

OTS maps will be available for all stages!

 

[mang.vang]

Sold! Hurry up and take my money

 

[Cheezy]

Sold! Hurry up and take my money

Please dont pressure him to hurry up, everyone did that before and we went 7 months without updates haha

 

[Aaron]

So maybe we should tell him to fuck off and we're all going to go buy AMG's!