E85 base map to flex fuel

Hi all can’t find a answer on the forum so thought would add a question.

I have a car tuned already to e85 running a haltech 2000ecu but I am wanting to get a flex fuel sensor so I can run on 98 pump. Will I be able to add the sensor and corrections in the ecu to allow for less then 85% ethanol fuel or do I have to have the initial tune done on 98 octane then add the corrections for ethanol fuel from there ?

Brendan,

Volumetric efficiency should not change so you should be in good shape to transition to a flex fuel tune as long as your injectors and data match well.

Please take this as my attempt to help without knowing for sure if it will work because I've not done this on that ECU and the flex fuel control is relatively limited. There may be a software specific caveat to this which I'm not aware of, but I believe the following is what you're wanting to do. If someone has insight on this specific ECU to suggest otherwise, please let us know, but since nobody has chimed in that they've done this, here we go...

Fuel comp scalar tables would be set to 100% at 0% ethanol, 0% at 85% ethanol so they have no impact on your existing E85 tune, full impact at 0% ethanol, and you would blend the values in between depending on your desired flex fuel behavior.

You'd use negative values in the various fuel composition correction tables so they reduce fuel delivery, reduce ignition advance, and reduce boost target as ethanol level decreases. For example perhaps -3 degrees timing if that's what you want to remove from your E85 tune when E0 is in the tank, and perhaps -30% in the fuel table, then adjust as needed.

Please let us know how it goes!