Flex/E85 tuning with 0411

[anniversaryss]

Finished up tuning on pump 93 getting ready to move to flex/e85. Have some basic questions. I understand the 0411 isn't amazing at it but it's what I got.

Let's say my Error on 93/E10 is roughly 1-2% at WOT and I run e85. When the pcm calculates the new target will it still be within the 1-2% error range? Probably not right?

As far as spark tuning goes when does the pcm start to use the ethanol table? A specific content? Or it kind of interpolates the spark in based on content? I'm assuming this is also hard coded?

Thanks
Bobby

[DrLoch]

I'm going to be doing the same thing in the near future. What base tune are you using for the flex/e85?

[anniversaryss]

I'm going to be doing the same thing in the near future. What base tune are you using for the flex/e85?

Im using the 02 Tahoe OS iirc

[Alvin]

This is a 02 Tahoe Cable throttle body 4l60 flex fuel for anyone that needs it.


02 Tahoe Flex '156.hpt

[anniversaryss]

This is a 02 Tahoe Cable throttle body 4l60 flex fuel for anyone that needs it.


02 Tahoe Flex '156.hpt

You can use the same OS from an avalanche if you need an 80e segment

[DrLoch]

Alvin, thanks. I'm still running a 4L60E

[anniversaryss]

Kinda common sense I suppose but just put in some flex , unknown content, into my 5/8 full tank and everything seems to work. Obviously have to use LAMBDA now lol. The percent error seems in line with what the AFR was but this was only an idle test

[aaronc7]

You don't *have* to use lamba. For this car I still just use gas scale AFR... works fine. Just make sure everything matches and you'll be good. I log equiv ratio, in gas AFR units. wideband reports gas AFR units.

[gametech]

You don't *have* to use lamba. For this car I still just use gas scale AFR... works fine. Just make sure everything matches and you'll be good. I log equiv ratio, in gas AFR units. wideband reports gas AFR units.

Exactly. I have seen people get way too hung up on units. The o2 sensor is only reading free oxygen anyway. You could be burning powdered sawdust for all it cares. Admittedly I have no idea what the octane rating on that would be, lol.

[kingtal0n]

You'll have more resolution with afr in gasoline scale also

https://www.theturboforums.com/threa...2#post-2056605

[anniversaryss]

Alright so logging Eq ratio I changed the units to AFR. And it seems to be going correctly.
Thanks guys I really appreciate it. Always learn something new .

[anniversaryss]

Got a little E in the tank. A low percentage since I had fuel in there anyways. I'm understanding how this works.
The AFR was on point which I'm happy about.
HPT is missing the spark blend factor table which is where I got confused but it's still present in the pcm. So depending on the amount of ethanol in the tank will depend on how much additional spark is added.

[Alvin]

I'm going to disagree and say its always better to deal with EQ or Lambda.

Any wideband you buy really deals with lambda or EQ then converts that into a AFR with an assume stoich point. The manuals always tell you what this is.. It could be 14.6, 14.7, 14.67 etc.

What this means is a car running straight ethanol or straight gasoline will read 14.7 (or whatever they assume stoich is) if it is at stoich. This makes a mess out of your maths as the stoich point is a moving target as fuel composition changes.

[aaronc7]

Got a little E in the tank. A low percentage since I had fuel in there anyways. I'm understanding how this works.
The AFR was on point which I'm happy about.
HPT is missing the spark blend factor table which is where I got confused but it's still present in the pcm. So depending on the amount of ethanol in the tank will depend on how much additional spark is added.

I can probably find the table and add it if you want to adjust the blend factor table, just send me the file or post it.

[DrLoch]

Any wiring related info for the flex fuel sensor?

[kingtal0n]

I'm going to disagree and say its always better to deal with EQ or Lambda.

Any wideband you buy really deals with lambda or EQ then converts that into a AFR with an assume stoich point. The manuals always tell you what this is.. It could be 14.6, 14.7, 14.67 etc.

What this means is a car running straight ethanol or straight gasoline will read 14.7 (or whatever they assume stoich is) if it is at stoich. This makes a mess out of your maths as the stoich point is a moving target as fuel composition changes.

What maths? Tune a 85% alcohol fuel car to 15.2:1 air fuel ratio idle/cruise. I tune a 10% alcohol fuel to 15.2:1 air fuel ratio at idle/cruise. Gasoline AFR easy

Targets are the same. Resolution is higher. The comp table for alcohol we pull 0.5 maybe 1.0 a/f out of the alcohol tune at 20-30psi of boost but again A. that isn't always necessary or even desirable and B. that is a much nicer, larger number with more resolution ticks per adjustment than lambda and C. Most of those compensation target adjustments for Flex are at boost levels higher than gasoline 10% alcohol will ever see so it could be embedded right into the base map, injection PW or VE table whatever computer you used.

[anniversaryss]

Any wiring related info for the flex fuel sensor?

I used an unused set of wires. In my case the EGR wire. I connected the 12v and the second wire I swapped at the pcm connector to blue connector pin 56 for the signal. Then ran a ground.

[DrLoch]

Copy. Thanks