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Flex Fuel Tuning

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Hi Andre

I just watched the Flex Fuel webinar.

Just wondering how you deal with tuning Flex Fuel on the older Vipec V88 series ecu's (or Link G4)

Setting up a 4D map for fuel and ignition with Ethanol % on the axis seems easy enough however what strategy do you recommend for adjusting cranking and warm-up enrichment as well as Boost control to suit the different requirements as the Ethanol % varies.


I've never actually done a flex fuel setup on the older firmware - I was either dedicated E85 or dedicated pump.

There obviously isn't an easy facility for modifying the cold start parameters for ethanol content though which is a little more challenging. I've just had a chat with another member here - Lith as I know he has done this exact setup. He dealt with cranking enrichment by adding fuel to the overlay table in the cranking areas. You find that it's the cranking enrichment that's affected more than the actual cold start on E85.

For Boost control I would set an axis of your boost target table to ethanol % and adjust your boost targets this way.

Thanks Andre

So just to confirm I understand correctly, Lith setup a 4D fuel table with rpm and Ethanol ℅ as the axis and adjusted the fuel at the cranking rpm to suit as the Ethanol ℅ changes.

Baring in mind I haven't actually needed to do this myself, I just had a quick play to see what the best options are. You've got a few options and what I'd consider would be using a switched overlay table and setting it up to switch via a virtual input. You could then set up the virtual output to switch above a certain E%. It's not obviously going to be a perfect solution but it will get the job done.

I don't have the tune in front of me but from memory did ethanol content and ECT as the axis and switched the table based off a Virtual Aux on the condition that rpm < 400rpm or thereabouts.

Thanks Guys