Flex Fuel Sensor Not Reading in S300 V3

[rofeksos]

So I just wired up a GM flex fuel sensor but it doesn't read ethanol content. I have the ground (black / white stripe) routed to the starter ground, power (pink / black stripe) is tapped into a fuse tap into the fuse box under the dash, and input (white) is wired up into AN0 of the Hondata board. I went into Flex Fuel options in Parameters and selected "Diatal S300 AN0 (S300 V3 only)". When I tested the sensor Analog 0 in Display did not show any voltage changes as I ran ethanol through the sensor (both in SManager and the Hondata app). I'm pretty sure I have it wired up correctly and I even double checked the power source I was using by swapping out my wideband source with the Sensor and vice versa and the wideband worked fine in both fuse ports. Attached you can see the wiring work done.

PS I originally had my wideband wired up into AN0 so I swapped it to AN1 input and it is still datalogging correctly.

S300 V3 (P28)
GM Flex Fuel Sensor
GM Flex Fuel harness
2.4k Ohm Resistor

[Hondata]

From the photos it does not look like it is plumbed into the fuel system yet. In that case, it will not read without fuel flowing through it.

Wiring could be improved. Ground should go to the thermostat ground. Power from injector power would be better, but not critical. Spade connectors should be switched to soldered and waterproofed connections.

[rofeksos]

You are correct it is NOT plumbed. However with the harness wired in, I plugged the sensor into the harness. I turned my car accessory on and with the sensor dangling there, I ran ethanol through it (I'm not tuned for E85 so I can't test plumbed in my fuel system) while datalogging but I don't see voltage changes. In SManager in the "Analog Input" tab, I first had it as "unused" in the original post. This morning I tried "custom" with voltage selected and lastly I tried "raw voltage". In all three cases, I could not get the sensor to display voltage changes. Am I missing something here?

I've attached my fuel map and datalogs. I hope it's just something I'm missing in my fuel map and not my wiring. I did the wiring on my AEM AFR into the ECU too and it's working so I feel confident the sensor is no different and should work.

As you stated I need to switch out my spade connections to soldered, which I will do. And I did switch the ground to the thermostat ground. If all else fails, I will re-wire everything.

[Hondata]

The output from the ethanol sensor is not voltage (it is PWM).

Under analog inputs do not select anything for Analog 0. Under Flex Fuel select Digital S300 AN0.

If fuel is not flowing through the sensor then it will usually output an error level, so your ethanol percentage will always show 0%. Depending where you are pump fuel will have an ethanol content and read above 0%.

[rofeksos]

Well it seems like my harness is not working. In my first post I originally had Analog 0 as "unused" (Analog Inputs tab -> Analog 0 -> Conversion selected is "Unused). Last thing I need to do is check that the wires are getting power. That's all I can think of as a last test before I rip out the harness and re-wire it again.

Stupid question but what the hell: do I need to have the car running in order to see the ethanol content while datalogging? Since I'm manually putting ethanol through the sensor by hand I didn't want to have the car running so I only turned the car on to accessory (but did not turn the car over).

[rofeksos]

So I tested my harness and it looks like it's getting power and ground to the plug. When I opened up the electrical tapes to double check I wired the colors correctly I noticed that my resistor broke off. This must be the issue. Will report back when I have this fixed

[Hondata]

Stupid question but what the hell: do I need to have the car running in order to see the ethanol content while datalogging? Since I'm manually putting ethanol through the sensor by hand I didn't want to have the car running so I only turned the car on to accessory (but did not turn the car over).

I've tried to be clear that ethanol sensors need fuel flowing through them to work. You can't pour fuel past the sensor.

[rofeksos]

I've tried to be clear that ethanol sensors need fuel flowing through them to work. You can't pour fuel past the sensor.

Gotcha. That totally went over my head. I got my harness fixed so I guess I'll plumb the sensor in my return line when I get the chance. I'm in SoCal OC area so hopefully the gas stations here have some amount of ethanol so that it will show up when I'm datalogging.

[Hondata]

Pump gas is right on 10% ethanol here.