[Eldi Z]

1.) If I simply add a certain % amount of Ethanol to the tank, will the ECM adjust timing automatically, or is a calibration necessary?

2.) Doing the same, but installing a Flex Fuel sensor.
Again, same question- Will the ECM compensate / adjust, or is a calibration of the maps necessary?

[CamaroDreams76]

The computer can only adjust a certain percentage. It isnt drastic. Calibration is necessary to run full E85. Flex fuel sensor with calibration allows for the sweep between 0% and 99%.

Pump 93 contains anywhere from 0-10% E. If your looking to run let's say 20% or more. Calibration is necessary. You can calibrate the ECU to run pump E but then you cant run 93. The sensor with calibration allows you to run whatever and the calibration will adjust the timing accordingly.

Adding a flex fuel sensor wont automatically work. After installation it needs to be turned on and the the necessary calibration needs to be made.

Hope this answers your questions.

[Eldi Z]

Thanks Camarodreams76.
My plan is to continue running on 93, but to have the option to add Ethanol in various percentages% - No more than ~ 15-20% of the tank being pure E (not pump E). I buy pure E in barrels, but never tried it on my 1LE. I use it for my BMW, where the DME (ECM) adjusts timing automatically. This is why I wondered if it is the same in the LT1 engine setup.
So, I will need a Flex Fuel sensor and then the ECM is going to adjust timing automatically when it senses the % of E that I have in the mix?
This automatic timing adjustment is going to be based on my existing tune, correct?
What is the sensor calibration procedure that is necessary after the installation?

[Joshinator99]

Originally Posted by Eldi Z

Thanks Camarodreams76.
My plan is to continue running on 93, but to have the option to add Ethanol in various percentages% - No more than ~ 15-20% of the tank being pure E (not pump E). I buy pure E in barrels, but never tried it on my 1LE. I use it for my BMW, where the DME (ECM) adjusts timing automatically. This is why I wondered if it is the same in the LT1 engine setup.
So, I will need a Flex Fuel sensor and then the ECM is going to adjust timing automatically when it senses the % of E that I have in the mix?
This automatic timing adjustment is going to be based on my existing tune, correct?
What is the sensor calibration procedure that is necessary after the installation?

Stock ECM & stock tune will not adjust timing vs E content. Will require flexfuel sensor and new tune as stated above. The tune will populate the flexfuel adder table which adds timing based on E content. This flexfuel timing table adds/subtracts from your base high octane timing table. There is no sensor calibration procedure to my knowledge. I don’t remember doing anything special when I added my sensor 6+ years ago.

[KingLT1]

You can run up to 15% without adding a sensor but it's stupid not to. If you are attempting this yourself A google search will pull up info on generic stoich and flex spark tables that can be used as a base to get started.

Any timing adjustments are based on the base High Octane spark table. Everything else is a modifier table. Flex Spark is a modifier table. For example, if you have 15 degrees as the WOT peak timing target in your Base table, the flex table will add timing on top based on the Flex spark and Ethanol % multiplier tables. The flex spark table is Zero by default, so it needs populated to see additional timing when you add Ethanol.

Another thing that is very important is to populate the Stoich table so the correct afr target for any given ethanol percent can be achieved. Its set 14.xx across all cells by default which is no bueno. If you don't do this and add E85 your fuel trims are going to peg +30% and you will likely get lean codes.

[Eldi Z]

Thanks all for your contributions and Josh and King for the detailed information. So interesting how different the DME's behavior @ BMW is with Ethanol compared to what GM is doing.
So basically, simply adding Ethanol to a 93 tank will do nothing in terms of the E92a adjusting the spark in the high-Octane table automatically from any existing "base" tune. Even when installing the FF sensor, a specific spark calibration for adding any % of E will be necessary

[Joshinator99]

Originally Posted by Eldi Z

Thanks all for your contributions and Josh and King for the detailed information. So interesting how different the DME's behavior @ BMW is with Ethanol compared to what GM is doing.
So basically, simply adding Ethanol to a 93 tank will do nothing in terms of the E92a adjusting the spark in the high-Octane table automatically from any existing "base" tune. Even when installing the FF sensor, a specific spark calibration for adding any % of E will be necessary

Correct

BMW is likely “inferring” the E content since it likely has OEM wideband O2 sensors much like the Gen3 Coyote. It can tell by the AFR what fuel you’re running and will slowly “learn” how much E you’re using. But that’s still inferior to a proper flexfuel setup with an actual ethanol sensor (that said I still wish we had OEM widebands lol).

[Eldi Z]

This is new to me. The O2 sensors in our engines / Exhausts are not WB??

Yes a proper FF sensor is precise and also available for the BMW engines, my tuning plaform (PTF = ProTuning Freaks, BootMod3/ BM3) also sells such sensor fully integrated with the Custom ROM
https://www.protuningfreaks.com/prod...y_UkR5-sUPnerW

[KingLT1]

No GM has used Narrow band since the 1980's up to 2019 in everything. The C8 and CTS-V Blackwing were the first to receive widebands for open and closed loop fuel control.

[RobZL1]

Originally Posted by KingLT1

No. GM has used Narrow band since the 1980's up to 2019 in everything. The C8 and CTS-V Blackwing were the first to receive widebands for open and closed loop fuel control.

Added a crucial period after the "No" above.

Let's eat grandma! I mean: Let's eat, grandma!

[Eldi Z]

Originally Posted by KingLT1

No GM has used Narrow band since the 1980's up to 2019 in everything. The C8 and CTS-V Blackwing were the first to receive widebands for open and closed loop fuel control.

OK, I get it, NB O2s during the 80s and 90s of the past century. OK, take it up to 2010, somehow acceptable...But all the way to 2019??!