Self-Tuning with the Flex Fuel XDF

[Jeffman]

I've begun converting my latest 93 pump bin (MHD with MBoost option and N20 TMAP scaled for +22psi boost) to Flex Fuel. I was able to convert my latest bin to the _FF version with the MOTIV FlexFuel converter for it to create the "_FF" version of the bin that can be read by the FlexFuel XDF. (Just for kicks I tried reading the original bin with the FlexFuel XDF and clearly got undecipherable tables lol.

Question: So I see that all of my normal 93 octane tables are populated everywhere, including the FlexFuel tables in the FlexFuel folder. See photo showing example of my 93 octane Fuel Scalar table being duplicated as the E85 Fuel Scalar table.

I separately have an E60 tune that I had created for my car; I have not created an E85 map since I only have LPFP Stg 2 pump. Assuming I never go over about 50% ethanol content, would it be best to simply copy and paste my particular E60 tables as the E85 Flex Fuel tables and adjust the interpolation so that the E% break point maximum is 60% instead of 80% ?

 

[Jeffman]

Here's something else that is interesting (sorry if it was already covered earlier). I wanted to start the tables at 10%E since my 93 pump bin was presumably tuned for 10% E. I tried to force the E breakpoints in the fuel table to be 10, 15, 20, 25, 30, 40, 50, 60%. Somehow the Flex Fuel XDF had it's own idea of what the breakpoints should be, which actually resulted in what looks like a pretty good interpolation curve between E10 (93 pump) and E60:

 

[matreyia]

Ich verstehe nur Bahnhoff!

(I only understand 'trainstation') <---- ie: this shit is Greek to me.

 

[Jake@MHD]

Hey Jeff,

Yes you can just copy and paste from your Ethanol tune into the appropriate (E85) tables. Please note that the fuel (spool) tables have shrunk so you will need to do them manually. And don't forget the fuel start (E85) and warm-up enrichment (E85).

When pasting the values, I would right click and view hex, and copy and paste the hex. This way you don't lose any resolution from hidden decimals.

For the XDF having a mind of it's own, do you mean how it changed them to 9.8, 29.8, etc? This is due to that field being 1 byte and it's scaling

 

[Jake@MHD]

Also, no reason to change the interpolation axis min/max to suit your blend. It "auto" interpolates between cells, so you don't need your hard breakpoints to be exact. I would especially leave the full E scale for load so that if you fill above E60 you can taper load however much needed.

 

[Jeffman]

Thanks Jake. You’ve answered my questions, as usual.

 

[langsbr]

When you build your initial flex fuel map, does it matter if you use a 93 tune or an Emix tune? Wouldn't you just modify the opposite values of whatever was used, or is there a reason to use a 93 tune?

 

[Jeffman]

When you build your initial flex fuel map, does it matter if you use a 93 tune or an Emix tune? Wouldn't you just modify the opposite values of whatever was used, or is there a reason to use a 93 tune?

If I understand your question, the base tune is for the lowest E content fuel you plan to run.

 

[Jeffman]

Hey Jeff,

Yes you can just copy and paste from your Ethanol tune into the appropriate (E85) tables. Please note that the fuel (spool) tables have shrunk so you will need to do them manually. And don't forget the fuel start (E85) and warm-up enrichment (E85).

When pasting the values, I would right click and view hex, and copy and paste the hex. This way you don't lose any resolution from hidden decimals.

For the XDF having a mind of it's own, do you mean how it changed them to 9.8, 29.8, etc? This is due to that field being 1 byte and it's scaling

Thanks again Jake, you are a gem!
Follow up question: My own custom tunes zero'd out the Load Target Per Gear table so that logic wasn't used. Upon converting my 93 Oct bin to _FF I see the Load Target Per Gear table now populated with a load of 140 in all of the Gear x RPM cells. Will the Flex Fuel logic still work if I keep both the 93 Oct and E85 Load Target Per Gear tables zero'd out?

EDIT: While double-checking my FF bin I see there is no longer any Load Target or Load Target (AT) tables in the FF XDF. Accordingly one must use the Load Target Per Gear tables.

 

[Jeffman]

REPORTING INITIAL RESULTS
I started out with 93 octane pump and did some logs. My key mods are Helix IC, charge pipe, DCI, Forge diverter valves, N20 TMAP, xHP Stage 3, LPFP Stg 2, for 22+ PSI, but n.b., stock turbos, stock catted downpipes, stock inlets and outlets, stock exhaust. Tune is initially designed to maximize boost / load / power.

93 Octane Pump (10% Ethanol)
I'm fairly pleased with this tune! The following WOT started off at around 2500 rpm in 3rd gear, then shifting to 4th at about 6100 rpm. The xHP Stg 3 shifting was firm and quick on this 56K miles AT. My messy timing above 4500 rpm should be cleaned up when I finally install my PR coils and new plugs. Virtual dyno recorded 381 HP / 461 TQ (73F, 3rd gear; smoothing = 2).

https://datazap.me/u/jeffman/flex-fuel-v12-73f?log=0&data=2-7-9-11-17-18-21-30&solo=2-11&zoom=37-116

56% Ethanol
I was expecting a lot more power and torque than the 93 octane - but it was a hotter and more humid day (82 F v 73F). Temps over 80F really suck a lot of power out of stock turbo cars. Virtual Dyno showed E56 yielded only a +12HP / + 12 ft-lb TQ increase over the 93 octane. Main tuning change was target AFR of 12.4 (E56) versus 12.0 (E10), and timing (12*) (E56) versus (8*) (E10). I suspect I may have too much ethanol at E56 for maximizing power, and than lowering to E40 should help somewhat.

Anybody have any other tuning suggestions to ensure max power at E40-E50? For example, increase timing further?

https://datazap.me/u/jeffman/flex-f...0&solo=2-4-11-12-21-22-23-24-25-26&zoom=30-85

Virtual Dyno Comparos for the above two runs (3rd gear data only):

E56 = TOP BLUE CURVES 93 OCT = BOTTOM RED CURVES

 

[langsbr]

In the VDyno chart, blue is the ethanol - why does it show less boost than the 93 (red) line? The datazap logs show the ethanol tune running up to 23psi, more than the 93. Am I reading it wrong?

 

[Jeffman]

Yeah, Blue is ethanol E56. Not sure why the boost is lower. I’ll need to check my load target per gear tables.
Edit: Both Datazap runs show Load Request about the same up top - 171-172. Not sure why the E56 log is lagging so much at 20psi at 151 load. I need to solve this mystery.

 

[matreyia]

Just installed and flashed to flex fuel staus... 3 am. Added 7 gallons ethanol is at 36.9%.
Flawless operation. This flex fuel kit is pretty amazing.

Power and response... feels like a different car...that's how insane the change was. I am impressed. It's like magic. Smoother idle and wot... everything is just smoother and more powerful.

Bravo jyamona, Motiv, and MHD.

Ngk .030
BL coil modified coil as per fmorelli's thread.
Dinan intercooler
Dinan oil cooler
Motul oil
KP steel oil filter
BMW Performance Exhaust
AFE CAI
ECS TUNING air scoops
VRSF DP
CSF aluminum radiator
PD transmission
ALPINA Flash
MHD V8 map
MHD ethanol maps
Motiv ethanol kit
ER charge pipe
TIAL BOV
PS Aluminum outlet
MMP inlets
M Factory LSD.
Precision Raceworks Stage 3 lpfp
N20 tmap

 

[Jeffman]

Just installed and flashed to flex fuel staus... 3 am. Added 7 gallons ethanol is at 36.9%.
Flawless operation. This flex fuel kit is pretty amazing.

Power and response... feels like a different car...that's how insane the change was. I am impressed. It's like magic. Smoother idle and wot... everything is just smoother and more powerful.

Bravo jyamona, Motiv, and MHD.

Ngk .030
BL coil modified coil as per fmorelli's thread.
Dinan intercooler
Dinan oil cooler
Motul oil
KP steel oil filter
BMW Performance Exhaust
AFE CAI
ECS TUNING air scoops
VRSF DP
CSF aluminum radiator
PD transmission
ALPINA Flash
MHD V8 map
MHD ethanol maps
Motiv ethanol kit
ER charge pipe
TIAL BOV
PS Aluminum outlet
MMP inlets
M Factory LSD.
Precision Raceworks Stage 3 lpfp
N20 tmap

Share some logs?

 

[matreyia]

Share some logs?

Will do this weekend. Swamped.

 

[matreyia]

It appears that the more e85 the more batshit the car wants to fly...incredible. I am now at 60% and it is insane. Will be curious to cross the supposed threshold where the car will lose power according to mhd and jyamona. As I understand it...it will begin to lose power after surpassing a certain percentage of e85. Don't know if it's 90% or over... anyone remember this warning?

 

[Jeffman]

E50 is the threshold.

 

[matreyia]

E50 is the threshold.

Really??? Well I guess there is something wrong with my car because it is around 63.9 or so and it is even faster than at 50%. I can barely control the car and that's with m3 suspension and bushings...I will try complete tank e85 to see if there is degradation. Will update.

 

[Jeffman]

Really??? Well I guess there is something wrong with my car because it is around 63.9 or so and it is even faster than at 50%. I can barely control the car and that's with m3 suspension and bushings...I will try complete tank e85 to see if there is degradation. Will update.

Yep. That’s what Jake says.

 

[langsbr]

Really??? Well I guess there is something wrong with my car because it is around 63.9 or so and it is even faster than at 50%. I can barely control the car and that's with m3 suspension and bushings...I will try complete tank e85 to see if there is degradation. Will update.

E50 is the threshold for when boost begins to return to 93 levels, but does timing as well? If you have added octane, even if you can't sustain the fueling needs for the higher boost, could it not sustain the timing? Could Matreyia's situation be that on E50 with higher boost there are timing corrections, and on E60+ with lower boost there are not, thus more power?