DIY Flex Fuel Schematic

EP3R-T

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From the info I've seen on here and elsewhere, this is what I've gathered as far as the electrical portion.
Can someone verify if my schematic is correct?
These colors aren't representative of the actual wires, just for ease of interpretation.

Honda Civic 10th gen DIY Flex Fuel Schematic IMG_1938
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Beholder84

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hobby-man

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That's the same that's on page 7 of this thread: https://www.civicx.com/forum/threads/guide-to-diy-flex-fuel-kit-for-hondata-or-ktuner.17482/page-7

I just started looking into this stuff myself, and am wondering why the need to use the ECT2 sensor? Does the converter just need a signal to piggyback from? I would rather not pay the (unreasonably IMO) high price for the pre-built PRL kit and just build it myself, but I want to know what I'm doing.
I dont think you have the option, Ktuner is set up to read ECT2 as the ethanol % (once converted). You'd need to rewrite the software to use a different sensor.

The idea is the GM sensor converts ethanol to a voltage and the KTuner converter translates the voltage back to ethanol % for the ECU. It's programmed to do it through ECT2 data line.
 

Beholder84

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I dont think you have the option, Ktuner is set up to read ECT2 as the ethanol % (once converted). You'd need to rewrite the software to use a different sensor.

The idea is the GM sensor converts ethanol to a voltage and the KTuner converter translates the voltage back to ethanol % for the ECU. It's programmed to do it through ECT2 data line.
Ah, ok now I see what's going on. What does the ECU use the ECT2 data for usually? I'm only concerned that by removing that data point from the ECU, something else might not work correctly.
 

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Ah, ok now I see what's going on. What does the ECU use the ECT2 data for usually? I'm only concerned that by removing that data point from the ECU, something else might not work correctly.
I can't remember exactly, I think something to do with radiator fan control? I think by default it uses ECT1 and ECT2 to control the fan together but when you enable flex fuel it just turns control over to ECT1.

@KTuner ?
 


Beholder84

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I can't remember exactly, I think something to do with radiator fan control? I think by default it uses ECT1 and ECT2 to control the fan together but when you enable flex fuel it just turns control over to ECT1.

@KTuner ?
I went for a drive this morning and logged a little while I was out. At one point my ECT was reading 181 and the ECT2 was 42 (degrees F). The ECT2 was closer to ambient at the time. Since the ECT2 sensor plugs into the radiator this makes sense, I wouldn't expect to see the ECT2 temp get higher unless I was beating on the car and it starts to get heat soaked. Looking though the KTuner settings, I'm not seeing anything that specifically calls out ECT2 as being used as a fan control parameter or anything, so not sure.
 

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Your wiring diagram looks correct to me. I’m planning to fab my own too, the PRL/Sirimoto kits are way overpriced.
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