Quote:
Originally Posted by Robbierayy1
Thank you for your response! But say I have a tank of 50% ethanol in my car which is below the 60% you mentioned to achieve MBT. Would the ecu retard the ignition timing once it recognizes the ethanol percentage to prevent knock? If we take the 70-75% tune as a reference point then if I were to be at 50% ethanol then wouldn't I be running rich at that moment? The 50% ethanol would be running on the stoichiometric ratio of 70-75% ethanol until the ecu adjusts and the fuel trims go negative to remove the amount of fuel being added to get to the right ratio for 50% ethanol right? If not how can I check the AFR so I could get a better understanding? Thank you for your time!
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Inless you have installed a flex fuel kit and flex fuel tune the ecu has no indication of ethanol %
The fuel trims work purely on the ecu adjisting fuel delivery to try to match commajded afr and measired afr.
If you dont have fill flex fuel setup then you need to run petrol on petrol tune and e85 on e85 tune but the tune can only adapt over a certian range of ethanol percent as it has no reference to ethanol percent.
If you want that you need to add flex fuel sensor and tune
http://www.ft86club.com/forums/showthread.php?t=120397
See here