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Subaru Flex Fuel Tuning Questions

Ethanol & Flex Fuel Tuning

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Discussion and questions related to the course Ethanol & Flex Fuel Tuning

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I have a 2005 Subaru Outback XT and I'm installing a flex-fuel kit on it. I'm tuning on the stock ecu, the flex-fuel kit I'm using takes the injector signal from the ecu and alters the pulse width based on the ethanol content the sensor is reading so that the AFR are correct. So it doesn't mess with timing, it just uses your gas fuel map to calculate the ethanol fuel map.

What I intend to do is make a separate map for the higher ethanol blends and have my gas map for if I fill up with under e70. For the Ethanol map I plan on increasing the timing, most likely I will rent some dyno time, but if that isn't possible I will get it as close as I can with virtual dyno.

From what I have been told subarus tend to need 4 to 6 degrees of timing added in to reach mbt timing, Is this true, or has anyone noticed some other trends?

Should i Lean out the lambda target at WOT on E85? Right now on Cali 91 octane with a TMIC i target 0.75 lambda at WOT, i feel like i may be able to go a little leaner on e85.

Is there anything else i should work on or look out for?

Thanks in advanced for all the help.

Hello i would be leaning the target out to .8 for ethanol and petrol and you are correct with the amount of ignition in boost only the vacuum area is generally the same timing on both fuels

regards Ross

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