E85 Flex Fuel sensor and ECT2 input

FlashPro questions & answers specific to the 2006-2011 Americas Civic Si
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Poindexter10thae
Posts: 2
Joined: Thu Sep 30, 2021 12:39 pm

E85 Flex Fuel sensor and ECT2 input

Post by Poindexter10thae »

I am currently using a GM 13577429 Flex fuel sensor, with a Radium Engineering split flow adapter plumbed into the feed line, still using the stock deadhead fuel system. The sensor has 12V+, GND, and signal is wired directly into ECT2, Pin A33.

When I Enable the flex fuel input, my ethanol content bounces all over the place, from 30% to 97%, with 93 octane gas, that is supposedly 0% Ethanol.

Based on some further digging, the GM 13577429 sensor outputs a frequency of 50-150hz, and the signal must be converted to a 0-5V output.

As opposed to buying an expensive controller box, or gauge, I'm opting to use an inexpensive PCB project board to convert frequency (HZ) to a 0-5V signal to input to the ecu.

Looking for some input as to if this has been done before or if it's a waste of time.

Ideally I would like to avoid spending an additional $150++ on adding flex fuel capability to my tune.
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