Flex fuel guys

[white1]

I'm fairly new to the hellcat platform, but have tuned several 5.7/6.4 cars and trucks and a couple of 3.6 trucks.

Anyway, I'm dabbling into a flex fuel tune for my car. I reached out to another tuner from HPT forum to help get me started and am trying to make headway. I understand fuel maps need to be perfect for the inferred flex to work properly, and I believe this is where my issue is based, but not 100% sure as to what's going on.

With the flex patch installed, I started the car and let idle in the shop and alcohol percentage was at 9.4% or somewhere around there (my memory isn't perfect)
I backed out the shop, and it went to 13%, drove home and it came up to about 30.5% it remained there for a while. A couple of days later I stopped and filled up and left the car running and the log going. When I got back in the car, it was showing 10.5% alcohol. Drove a few days went to the race track, and filled up on the way home. Was still reading about 10.5%, but after filling up, its been swinging between about 10.5 up to 40 back to 30.5 and now down to about 20.4

My long term fuel trims are at 0.00 logging my injector fuel mass vs pulse width is such a small correction that when I try to correct the fuel mass, it doesn't even change (-0.36%)

I really dont have much problem going strictly e85, however would prefer to go flex for any rare occasion when the e85 pump is down, or if I'm on a trip and cant find e85. Not to mention to just learn exactly how it operates for my knowledge.

I could easily pay the person who helped set me up with the flex patch (so easy in hindsight) but I'm not a huge fan of paying other tuners for something I will possibly be using on customer vehicles in the future. I personally don't mind helping others, but I understand some tuners don't want information they've developed through trial and error shared, and I respect that fully

 

[white1]

To add. Which the patch installed, my fuel trims are at 0
With the patch not installed I’m still pretty much at zero. I noticed a max of -1.7 LTFT and PW at -0.56 on the ride home.
With the patch the wideband will display about 11.7-12.4 depending on alcohol content (I understand this is how it infers alcohol content)
The log will show about .94 lambda
Without the patch the wideband displays 13.6/7 and the log will show 1.00 lambda

all readings are part throttle

 

[Speedy!]

There are a couple variables that impact the calc. The main one is the STFT. You have to have the injector data spot on to get calcs correct and even then 10% from actual is VERY good. I've found mine is more accurate for calculating ethanol than it is gasoline. On straight 93 I'll see 7% to 20% depending on what it decides on. On E85 it's like E82 to E85.

Mike from OSTDyno trained me for about a year on tuning these cars. Some stuff I figured out on my own for flex fuel, some stuff he taught me. Anything I learned on my own I'm happy to share to help.

What's the setup on the car? What injectors? I've been running Injector Dynamics injectors and in my experience I could get cruise/drive/wot trims dead nuts. So say cruising I'm at .6 inj pw the trims would be within 2-3%. At idle at that same inj pw of .6 the trims might be +10%. That will adversely impact calcs as an example.

Also be very careful with the ehthanol multi table under Power Enrich as it relates to the stoich points for the different ethanol % and PE adder table. Get that wrong and you might be good to go for PE fueling on E85 and severely lean on 93.

Obviously add timing last after everything else works like it's supposed to. I set my alcohol wot timing table to match that of 93 while I was testing.

 

[white1]

There are a couple variables that impact the calc. The main one is the STFT. You have to have the injector data spot on to get calcs correct and even then 10% from actual is VERY good. I've found mine is more accurate for calculating ethanol than it is gasoline. On straight 93 I'll see 7% to 20% depending on what it decides on. On E85 it's like E82 to E85.

Mike from OSTDyno trained me for about a year on tuning these cars. Some stuff I figured out on my own for flex fuel, some stuff he taught me. Anything I learned on my own I'm happy to share to help.

What's the setup on the car? What injectors? I've been running Injector Dynamics injectors and in my experience I could get cruise/drive/wot trims dead nuts. So say cruising I'm at .6 inj pw the trims would be within 2-3%. At idle at that same inj pw of .6 the trims might be +10%. That will adversely impact calcs as an example.

Also be very careful with the ehthanol multi table under Power Enrich as it relates to the stoich points for the different ethanol % and PE adder table. Get that wrong and you might be good to go for PE fueling on E85 and severely lean on 93.

Obviously add timing last after everything else works like it's supposed to. I set my alcohol wot timing table to match that of 93 while I was testing.

Ripa 2.79' upper, FIC 1000cc injectors, catless mid pipes and LMI cold air (more for sound than anything else)
Ive never paid much attention to STFT as I know they will swing depending on driving conditions.

With you mentioning STFT, I wonder how accurate Ill ever see with in town driving? Maybe I should stretch it out on some longer trips and see how things look?

 

[ACMAVRO]

Above my pay scale, but interesting stuff. Sub’d

 

[Speedy!]

Ripa 2.79' upper, FIC 1000cc injectors, catless mid pipes and LMI cold air (more for sound than anything else)
Ive never paid much attention to STFT as I know they will swing depending on driving conditions.

With you mentioning STFT, I wonder how accurate Ill ever see with in town driving? Maybe I should stretch it out on some longer trips and see how things look?

Please don't take this the wrong way, but if you don't have a good understanding of STFT and how to get them as close to zero as possible, I'd hire a pro tuner to do a flex fuel tune for you. It takes time, or experience, sometimes both, to get the injectors dialed in. For standard tuning the Hellcat is pretty forgiving and getting the STFT under 10% is OK. For flex it has to be VERY close or the calcs are all over the place. Mine are within about 3% as an example cruising around town WOT, everywhere. That's just one of a dozen or so things that need to be right for flex fuel. Took me a year to learn it and that was with guidance from Mike at OST.

 

[white1]

Please don't take this the wrong way, but if you don't have a good understanding of STFT and how to get them as close to zero as possible, I'd hire a pro tuner to do a flex fuel tune for you. It takes time, or experience, sometimes both, to get the injectors dialed in. For standard tuning the Hellcat is pretty forgiving and getting the STFT under 10% is OK. For flex it has to be VERY close or the calcs are all over the place. Mine are within about 3% as an example cruising around town WOT, everywhere. That's just one of a dozen or so things that need to be right for flex fuel. Took me a year to learn it and that was with guidance from Mike at OST.

I by no means know everything. Im a professional tuner, but new to the hellcat platform. As far as my understanding on pretty much everything else, its all based around LTFT and injector fuel mass vs pulsewidth. Those are spot on (within 1%) but I do know the hellcats use a widband whereas nothing else I tune uses a wideband, much less in closed loop. Im assuming thats where my issue lies.
Nothing else I tune has any real STFT adjustment other than fuel mass vs pulse width.

By no means am I taking anything you say the wrong way. If I didnt have any issues I wouldnt have ask lol.

But you did confirm what I was wondering, which is whether or not the STFT is whats affecting my alcohol percentage reading. Thanks!

 

[white1]

Please don't take this the wrong way, but if you don't have a good understanding of STFT and how to get them as close to zero as possible, I'd hire a pro tuner to do a flex fuel tune for you. It takes time, or experience, sometimes both, to get the injectors dialed in. For standard tuning the Hellcat is pretty forgiving and getting the STFT under 10% is OK. For flex it has to be VERY close or the calcs are all over the place. Mine are within about 3% as an example cruising around town WOT, everywhere. That's just one of a dozen or so things that need to be right for flex fuel. Took me a year to learn it and that was with guidance from Mike at OST.

After your response I did a little more searching....
Maybe you can help me understand? From all my past tuning experience, Ive been taught not to worry with part throttle STFT as they will constantly change based on load. Throttle input, airflow, grade, etc etc etc.

I keep having to remind myself that I have a wideband controlling fueling in closed loop even during WOT. I havent really made any WOT pulls with the patch installed. Im starting to wonder, after reading more post about the flex patch if I might be making a mountain out of a mole hill? Ill try and see when I can make some WOT logs, and see how things look. I cannot for the life of me find anything for STFT tuning other than injector fuel mass vs pulsewidth, and as mentioned im less than 1% off there

Whether Im on the right track or not, I do appreciate the comments!

 

[Speedy!]

Yes, Hellcats are wide band ALL the time. Makes tuning a lot easier for stuff I've done. I'm not a pro by any means, just self taught with some help from a pro and the Hellcat is the deepest I've gotten in to so take that for what it's worth.

From what I've heard, Dodge tuning is wildly different than other manufacturers so I wouldn't try to apply much of anything else to it, if that makes sense.

Fuel trims are controlled with the injectors as you've mentioned, but you have to get STFT dialed in very tight, and I recommend something less than 5%. I wouldn't even load a FF tune until I had that done on standard pump gasoline.

 

[white1]

Yes, Hellcats are wide band ALL the time. Makes tuning a lot easier for stuff I've done. I'm not a pro by any means, just self taught with some help from a pro and the Hellcat is the deepest I've gotten in to so take that for what it's worth.

From what I've heard, Dodge tuning is wildly different than other manufacturers so I wouldn't try to apply much of anything else to it, if that makes sense.

Fuel trims are controlled with the injectors as you've mentioned, but you have to get STFT dialed in very tight, and I recommend something less than 5%. I wouldn't even load a FF tune until I had that done on standard pump gasoline.

ive been tuning strictly hemis for a little over three years.
I’ve not done many hellcats, and mine is the first I’ve attempted the flex tuning on.
I did pay someone to help me get started and he has offered to help with the fueling.

I’m just trying to understand exactly what I’m not understanding hahaha

if FM vs PW is zero, and my LTFT are zero I’m not sure where to go to make any changes that will affect STFT
VE tables shouldn’t matter with ANN on, it should all be FM vs PW from everything I’ve learned and that is all as close to perfect as I can ask for.

I’m just chalking it up to learning a new platform of sorts.

without the patch, hellcats are way easier to tune because of the widebands, but this is most likely something simple I’m over looking.

its hard for me to do much with my personal car. Either I’m busy with customers stuff, or I just want to relax.
I’ve yet to have a customer request a flex tune, but when that time does come I’d like to have a better understanding of the what’s, whys and how’s than I have right now

 

[1971demon]

Above my pay scale, but interesting stuff. Sub’d

Lmao..pay scale???..I have an easier time understanding Hickster with half a kettle of shine in em..as interesting as it is..it's so far over my head...it defies gravity...

 

[parttimer]

Not sure how much this may help. When I went to flex tuning my tuner had me tune on pump gas, then after that part of the tune was good, run the tank low, fill halfway on E85, run that down then fill up. One thing I noticed was even after 2-3 fill ups my E content wouldn't go past 50 or so. He did some sort of revision and had me reload the tune then it was reading proper. Did a few revisions on E85 then I was done. I didn't run a mix to get flex, it was 93, then E85 and done.

 

[white1]

Not sure how much this may help. When I went to flex tuning my tuner had me tune on pump gas, then after that part of the tune was good, run the tank low, fill halfway on E85, run that down then fill up. One thing I noticed was even after 2-3 fill ups my E content wouldn't go past 50 or so. He did some sort of revision and had me reload the tune then it was reading proper. Did a few revisions on E85 then I was done. I didn't run a mix to get flex, it was 93, then E85 and done.

I have zero plans of going flex until i feel comfortable with the alcohol percentage. Im still waiting on my fuel pumps, but if I cant get the alcohol stuff worked out ill either
a) verify ethanol content in the tank by taking a sample from the fuel rail and compare that to the log
b) just go straight e85 tune

I use my car as a guinea pig, but don't want to swap engines due to my own ignorance/being impatient. At least not from this. There is a good chance Ill be swapping engines one day to my own ignorance/being impatient, but hopefully not due to flex testing haha

 

[ACMAVRO]

Im still waiting on my fuel pumps

Still waiting on mine too from Tapped

 

[white1]

Still waiting on mine too from Tapped

I did talk with him last week, and that weather they got put them behind. I keep anxiously checking though haha

 

[FFBOS]

I have zero plans of going flex until i feel comfortable with the alcohol percentage. Im still waiting on my fuel pumps, but if I cant get the alcohol stuff worked out ill either
a) verify ethanol content in the tank by taking a sample from the fuel rail and compare that to the log
b) just go straight e85 tune

I use my car as a guinea pig, but don't want to swap engines due to my own ignorance/being impatient. At least not from this. There is a good chance Ill be swapping engines one day to my own ignorance/being impatient, but hopefully not due to flex testing haha

Only one true flex tune out there that reads fuel right off the rail....

 

[white1]

Only one true flex tune out there that reads fuel right off the rail....

id definitely prefer to install an alcohol sensor and wire into the PCM but wasn’t aware that was an option for us at this time

 

[FFBOS]

id definitely prefer to install an alcohol sensor and wire into the PCM but wasn’t aware that was an option for us at this time

There is

 

[white1]

There is

Could you/would you care to elaborate?

 

[Speedy!]

Keep in mind only one OEM (GM) uses a sensor for their factory FF vehicles. Not saying it's not better than inferred, but GM is the only one doing it that way that I'm aware of.

Satera has a solution, but I think it requires splicing or adding some wiring to the harness/pcm:

https://sateratuningstore.com/mopar-true-flex-fuel/

But they're kinda weird about the whole deal with in house install only, limited tuners, etc. That would be a concern for me.