Help me understand E85

[hockale1]

For some reason known only to Ford, they turned off the flex fuel setting in the mustang ECU. All the tuners do for a flex tune is flip the switch and fill in a few tables that ford left zeroed out.

Generally correct, though some of the important bits of flex fuel are straight up missing, so even with flex fuel enabled and ff cals filled in, there Is still some functionality that is missing compared to f150.

EDIT: So as not to mislead anyone looking at this years down the line, for 15MY (and possibly 16MY-17MY), flex fuel tunes are limited in their ability to modify spark based on ethanol content. @K4fxd brought it to my attention that at least the 19MY tune has this capability.

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[K4fxd]

there Is still some functionality that is missing compared to f150.

Like what?

 

[LOL WUT]

Usually it’s around 10:1 and typically fuel is around e70-e95

How are you measuring E content? E95 is absurdly high from a pump.

 

[Xavier208]

How are you measuring E content? E95 is absurdly high from a pump.

Rev X tester
That pump consistently comes out to e90-95 tested by me and others in the area

 

[Strokerswild]

Rev X tester
That pump consistently comes out to e90-95 tested by me and others in the area

While I've never tested it explicitly, my nGauge frequently indicates that my usual station runs 90-91% during the summer months. So it is possible.

I always wonder about the true accuracy of the nGauge, but since the car runs a flex tune I don't worry about it.

 

[K4fxd]

Generally correct, though some of the important bits of flex fuel are straight up missing, so even with flex fuel enabled and ff cals filled in, there Is still some functionality that is missing compared to f150.

Again what is missing. As far as I can find it is the same ECU and software.

 

[hockale1]

Again what is missing. As far as I can find it is the same ECU and software.

Pull up an F150 tune and compare it to a S550 tune. You will find that there are no flex fuel dependent borderline tables, mbt tables, or flex fuel blenders for aforementioned tables. About all they give you are tables for getting the AFR to calculate correctly and some cold start stuff, nothing for spark.

 

[hockale1]

Rev X tester
That pump consistently comes out to e90-95 tested by me and others in the area

Holy shit, well that fully explains your low range. Overall I’d say you’re doing just fine, but I would be somewhat concerned about your injector pulsewidths getting maxed out with those E90 and above fuels. Are you running factory injectors?

 

[Xavier208]

Holy shit, well that fully explains your low range. Overall I’d say you’re doing just fine, but I would be somewhat concerned about your injector pulsewidths getting maxed out with those E90 and above fuels. Are you running factory injectors?

Yeah factory injectors

 

[K4fxd]

Pull up an F150 tune and compare it to a S550 tune. You will find that there are no flex fuel dependent borderline tables, mbt tables, or flex fuel blenders for aforementioned tables. About all they give you are tables for getting the AFR to calculate correctly and some cold start stuff, nothing for spark.

This is a 2019 GT mustang tune and........

 

[hockale1]

This is a 2019 GT mustang tune and........

Ok fair enough, I’ve not looked at 19MY+ calibrations, I’m more focused on 15MY. Perhaps with upgrade 3 and PFDI it was added. Good for those folks!

 

[K4fxd]

On the 2 gen you can use the octane adjustment under borderline corrections.
Ford uses this table on the 2 gen F150's also.

 

[hockale1]

This is a 2019 GT mustang tune and........

Is that just the knock modifier or are there also independent borderline tables for each mapped point?

 

[ChitownStang]

Just tested another gas station by me in Chicago area. Both Thortons and Woodmans-
67%
You guys are lucky getting that good of E85. No point for me to run a E85 or Flex in this area.

 

[K4fxd]

It uses that table and another to increase borderline spark due to octane. When the logic senses anything over E20 or so it calculates spark using this modifier.

The gen 2 uses 1 table to do the same. There is more resolution in the Gen3's

A head scratcher, the F150 uses less total advance than the GT even under FFV tuning when using optimum power tables.

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