s8v4o
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For anybody wanting to know more here is the link.
http://www.hptuners.com/forum/showthread.php?50917-Flex-fuel&highlight=flex+fuel
From what I can gather the O2 sensor still just reads oxygen, no surprise there. What's actually happening is upon enabling flex fuel in the ECU you unlock a few new tables that were dormant. The ethanol content is inferred data based on how far off the AFR is. If the AFR is 30% off of what the ECU thinks it should be it will calculate how much ethanol it thinks is in the fuel and then adjust the new demands on the new tables that were enabled. Exactly what tables are enabled I'm not sure. My guess would be a new ignition timing table and fuel table at the very least
http://www.hptuners.com/forum/showthread.php?50917-Flex-fuel&highlight=flex+fuel
From what I can gather the O2 sensor still just reads oxygen, no surprise there. What's actually happening is upon enabling flex fuel in the ECU you unlock a few new tables that were dormant. The ethanol content is inferred data based on how far off the AFR is. If the AFR is 30% off of what the ECU thinks it should be it will calculate how much ethanol it thinks is in the fuel and then adjust the new demands on the new tables that were enabled. Exactly what tables are enabled I'm not sure. My guess would be a new ignition timing table and fuel table at the very least