Flex Fuel Tune Question / pros cons

[engineermike]

@K4fxd what’s your time to mature set to? I’ve seen 5-10 seconds in stock flex, but we know other conditions have to be met.

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[K4fxd]

I set it to 40, counts to 40 also.

 

[ZXMustang]

I just increased the time for it to learn parameters. The only problem so far is if set too high I need to drive on the freeway for several miles.

I found letting it idle for a long period of time at the start gets the E content up faster than driving. You can see because when you let off, the ARF pegs to 20 and the car will either learn back down from that or pause learning. Its best to let it idle the E content up, then when its in the 60ish range E, then I do light driving trying not to coast. I have HOURS AND HOURS of testing with the flex tunes and a mountain of logs and all I can tell you from experience it its very flawed. My car even with e90 tested, wont seem to learn up past 77. No matter what I do. I found a GATE gas station that consistently has E85-90 tested by me and a few others, and no matter how long I let it learn or what I do it seems to cap around 77. This is why I think the static E tunes are best. My car even on the pure E85 I can get, seems to be happiest around 10.20afr. Then for wot, .85 lambda.

 

[engineermike]

@ZXMustang who is doing your tuning?

 

[engineermike]

I also came across this https://www.advancedfueldynamics.co...lex-dx-for-2018-23-5-0l-mustang-gt-and-mach-1

which says no tune required and looks more "oem", any thoughts on that?

That’s an interesting find. Looks like it basically senses ethanol content and modified injector pulsewidth accordingly
thereby holding lambda constant. The pcm is ignorant to the change because it’s only way to know the ethanol is through lambda correction, which isn’t required (by the pcm at least). Pretty neat way to add flex without having to flash it.

However, two disadvantages come to mind. Aside from lack of knock allowing more knock advance, there’s no mechanism to add more timing. Secondly, since the pcm is blind to the actual pulsewidth sent to the injectors, then it doesn’t know when exactly the torque will be injector-limited so it doesn’t know when to cut the throttle for lack of fuel. This could be especially bad since the kit appears to keep the stock fuel system which could be insufficient on e85..

 

[stannypack]

That’s an interesting find. Looks like it basically senses ethanol content and modified injector pulsewidth accordingly
thereby holding lambda constant. The pcm is ignorant to the change because it’s only way to know the ethanol is through lambda correction, which isn’t required (by the pcm at least). Pretty neat way to add flex without having to flash it.

However, two disadvantages come to mind. Aside from lack of knock allowing more knock advance, there’s no mechanism to add more timing. Secondly, since the pcm is blind to the actual pulsewidth sent to the injectors, then it doesn’t know when exactly the torque will be injector-limited so it doesn’t know when to cut the throttle for lack of fuel. This could be especially bad since the kit appears to keep the stock fuel system which could be insufficient on e85..

Thinking of going sct x4 + juggernaut flex

but after a couple of track days and more beating on the car to make sure I don't have a lemon

 

[K4fxd]

My car even with e90 tested, wont seem to learn up past 77

I've got my flex parameters set from 9 to 14.6. my car will learn 90%

 

[engineermike]

I've got my flex parameters set from 9 to 14.6. my car will learn 90%

You must have end-point locking disabled or modified vs ford’s settings.

 

[Mikepol2]

It feels like we are overthinking this.

Get Livernois or Wengerd flex tune.

Put flex fuel in your car.

Enjoy the improved performance.

 

[ZXMustang]

I've got my flex parameters set from 9 to 14.6. my car will learn 90%

Do you have it logged showing that level of E content? I'd like to see it.

 

[K4fxd]

Do you have it logged showing that level of E content? I'd like to see it.

Next time I get above 85% I'll post a screen shot.

 

[CR151S]

I found letting it idle for a long period of time at the start gets the E content up faster than driving. You can see because when you let off, the ARF pegs to 20 and the car will either learn back down from that or pause learning. Its best to let it idle the E content up, then when its in the 60ish range E, then I do light driving trying not to coast. I have HOURS AND HOURS of testing with the flex tunes and a mountain of logs and all I can tell you from experience it its very flawed. My car even with e90 tested, wont seem to learn up past 77. No matter what I do. I found a GATE gas station that consistently has E85-90 tested by me and a few others, and no matter how long I let it learn or what I do it seems to cap around 77. This is why I think the static E tunes are best. My car even on the pure E85 I can get, seems to be happiest around 10.20afr. Then for wot, .85 lambda.

how long is appropriate to idle???
I might try this in the future.

 

[ZXMustang]

how long is appropriate to idle???
I might try this in the future.

You can watch the afr gauge on the dash to see it come down to the low 10s or you can watch the logs to see the trims and inferred e content go up. It’s usually about 10 minutes.

 

[AWESOMO 4000]

It feels like we are overthinking this.

Get Livernois or Wengerd flex tune.

Put flex fuel in your car.

Enjoy the improved performance.

Agreed. Was in the same boat. Because a dedicated E85 tune ramps in timing quicker the tuners have to state you need to test the fuel to avoid any potential issues. They also say the bulk of your gains are had by about 68%.

We really haven't been deluged with reports of people having terminal failures on dedicated tunes or Flex for that matter...where the issues arise is if their Flex tune in December isn't operating exactly like stock during winter. There's like 5+ years of data and customer experience...no need to reinvent the wheel. There's tens of thousands of these things out there running around now without issue.

 

[stannypack]

Agreed. Was in the same boat. Because a dedicated E85 tune ramps in timing quicker the tuners have to state you need to test the fuel to avoid any potential issues. They also say the bulk of your gains are had by about 68%.

We really haven't been deluged with reports of people having terminal failures on dedicated tunes or Flex for that matter...where the issues arise is if their Flex tune in December isn't operating exactly like stock during winter. There's like 5+ years of data and customer experience...no need to reinvent the wheel. There's tens of thousands of these things out there running around now without issue.

Ordered a SCT BDX today for 320 with a 45 rebate from Beefcake, and will be ordering the flex tune from Juggernaut later

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