Motiv Flex Fuel vs Bluetooth

ansch

Lurker
Sep 23, 2018
13
2
0
Ride
E82 135i SGM
So I tested the grey wire out of the fuel-it bluetooth sensor today with a voltmeter. With the car running, I'm not getting any voltage (77mV on the meter). Does this mean I actually have the raw output version? I don't have a scope so can't check for PWM.

If that's the case then I'd need to convert the frequency output to voltage. Been searching around to see what options I have. Obviously I can just get the motive box but being in Australia means shipping cost kills the fun. There are a few homebrew arduino projects that can work if I could be bothered. (I do have a nano lying around). Then I came across this (http://www.p3cars.com/accessories/p3-ethanol-sensor-voltage-adaptor/). Which is meant to be an interface for the P3 gauges but it's exactly what I'd need right? Convert the frequency to 0-5v and tune via mhd to suit.
 

tortue-xTz

Lurker
Jul 19, 2020
11
0
0
If you're custom-tuned then you can adjust the voltage to ethanol content to suit, but the OTS mhd maps would be tuned specifically on the motiv I'd assume and there's no way to adjust it at flash time.
Ok, thanks for the clarification !
i'm on OTS map, so this solution is not the right for me at the moment.
But i plan to have a custom tune when the car will be FBO, so i'll keep that in mind if i don't find a fix for my problem until this day ;)
 

ajm8127

Specialist
Jul 16, 2020
69
129
0
PA - US
Ride
2007 E90 335i
Then I came across this (http://www.p3cars.com/accessories/p3-ethanol-sensor-voltage-adaptor/). Which is meant to be an interface for the P3 gauges but it's exactly what I'd need right? Convert the frequency to 0-5v and tune via mhd to suit.

The DME reads a voltage which changes with ethanol content. Any device that reads the frequency of the sensor output and changes this into a voltage range should work. So yes, the P3 adapter should work. The Zeitronix ECA-2 should also work as it connects to the sensor and outputs a 0-5 V signal proportional to the ethanol content. The P3 is cheaper, but my point is there are options.

Even if you have an OTS tune, changing the proper map to re-scale the DME input should be easy (assuming you have the correct licenses). There are two maps called "Ethanol Sensor Conversion" and "Ethanol Sensor Conversion Axis" that need to be set appropriately. Here they are already setup for a 0-100% ethanol concentration corresponding to a 0-5 V input (the right most map). If the DME reads a voltage of 2.5 volts, the ethanol concentration would be interpreted as 50%.


I took that from the first post of this thread.
 
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Reactions: ansch and fmorelli

dwspen01

New Member
Mar 8, 2017
6
3
0
Ride
2009 BMW Z4 35i DCT
I have the Motiv Flex Fuel Module and a P3 Cars Vent gauge and would like to run the 0-5v signal from the Flex Fuel Module to the analog input of the gauge. Which wire on the Motiv module is the 0-5v output signal?