Motiv Flex Fuel Installation Guide

NoGuru

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Jan 9, 2018
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Anyone know what the ECA voltage should be at. Mine sits at 1.1 and shoots to 4.46 as soon as I hit the gas a little and Ethanol goes from reading like 23% to %100.
 

Jake@MHD

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Nov 7, 2016
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Anyone know what the ECA voltage should be at. Mine sits at 1.1 and shoots to 4.46 as soon as I hit the gas a little and Ethanol goes from reading like 23% to %100.

Sounds like symptoms of a bad harness IIRC. Please contact Motiv for warranty.
 

matreyia

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Apr 19, 2017
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The higher the ethanol, the lower the voltage. If you are spiking, when stepping on the gas, then you have a wiring fault or your flex fuel unit is about to go bad. I had the first gen unit replaced last year under warranty and I am on the second one, which looks different than the first gen. because it has no usb tail end. I also ordered a third unit and it sits in my glovebox as a backup, because you are s.o.l if your unit goes bad and you are out far from home. Unless you do not have port injection and you can simply reflash to stock settings and limp home. If you have port injection, then you have to disconnect the port injection, reflash to stock or MHD stock flex fuel flash.
 

matreyia

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Apr 19, 2017
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False, higher voltage = higher ethanol.

I confirm that I am at 76.2 % ethanol and 2.4 voltage. Looking at MHD readings as I write this. Amd it concurs with my past observations that higher ethanol makes for lower voltage. So I don't know why your observations are the opposite. Is there a setting I am unaware of?
 

Jake@MHD

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Nov 7, 2016
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I confirm that I am at 76.2 % ethanol and 2.4 voltage. Looking at MHD readings as I write this. Amd it concurs with my past observations that higher ethanol makes for lower voltage. So I don't know why your observations are the opposite. Is there a setting I am unaware of?

4V, 4.5V, and 5V are error conditions and do not count. The main voltage to ethanol scale is 0.5V - 3V (or 3.5V I forget off hand), which correlates to 0-100% E. So in the actual range, the higher voltage is higher ethanol. 4V and above are not proper readings and mean you have a hardware or wiring issue.
 
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matreyia

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4V, 4.5V, and 5V are error conditions and do not count. The main voltage to ethanol scale is 0.5V - 3V (or 3.5V I forget off hand), which correlates to 0-100% E. So in the actual range, the higher voltage is higher ethanol. 4V and above are not proper readings and mean you have a hardware or wiring issue.

Ah.
 

doublespaces

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Oct 18, 2016
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Thanks @doublespaces, I appreciated the guide. It helped me get the wiring mostly done tonight.

I've had the flex fuel sensor hooked up for a while, although I kinda wish I ran the wire to it after I did the wiring under the ECU box. Need to figure out how to get it into my ecu box and also need to go buy some positaps.
 

NoGuru

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Jan 9, 2018
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Motive sent me a new wiring harness and I installed it, just like it was before. Double and triple checked that is was wired correctly.
Started the car and idle is wildly jumping and throwing codes. E was pegged at 100% and ECA was reading 3.3.
Really want to drive this car so any help will be deeply appreciated.

- DME active codes -
2CFA - DME: Throttle-valve potentiometer 2.
2CFB - DME: Throttle-valve adaptation value.
2D09 - DME: THROTTLE.
2D1D - DME: Accelerator-pedal module, pedal-position sensor 1, voltage supply.
 

langsbr

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Apr 5, 2017
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are you running a custom tune? If so, you might try flashing an older rev. I had a version that was completely toasted and had to get my tuner to rebuild it.
 

NoGuru

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are you running a custom tune? If so, you might try flashing an older rev. I had a version that was completely toasted and had to get my tuner to rebuild it.
I am but the problem is this is a base map for my new Turbos, and my tuner is sick.....
Maybe I will just reflash and see what happens.
 

langsbr

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Apr 5, 2017
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You get these errors just cranking the car right and not at WOT? I can run a generic map thru the flex fuel builder if you want to try it. Just need to know what DME you have.
 

NoGuru

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Jan 9, 2018
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You get these errors just cranking the car right and not at WOT? I can run a generic map thru the flex fuel builder if you want to try it. Just need to know what DME you have.
I have MSD81
This was just starting the car, it's not drive-able. In fact, just re flashed my map and now it won't start.

Maybe I knocked a wire off somewhere. I will have to retrace my steps again once it warms up. Thanks for the help langsbr.
 

matreyia

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Apr 19, 2017
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I have MSD81
This was just starting the car, it's not drive-able. In fact, just re flashed my map and now it won't start.

Maybe I knocked a wire off somewhere. I will have to retrace my steps again once it warms up. Thanks for the help langsbr.

You already reset all adaptations including the throttle adaptation and then turn on accessory position, waited 30 seconds and then started the car? If so, there is a mixed wire.
 

matreyia

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Apr 19, 2017
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Thanks @doublespaces, I appreciated the guide. It helped me get the wiring mostly done tonight.

I've had the flex fuel sensor hooked up for a while, although I kinda wish I ran the wire to it after I did the wiring under the ECU box. Need to figure out how to get it into my ecu box and also need to go buy some positaps.

The wire can be laid on top of the seal between the lid and seal and it should seal fine when you lock the lid down. That's how I did it.
 
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NoGuru

Captain
Jan 9, 2018
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You already reset all adaptations including the throttle adaptation and then turn on accessory position, waited 30 seconds and then started the car? If so, there is a mixed wire.
Yep, reset idle, throttle and octane adaptations. I did not wait 30 seconds though. I am leaning towards a mixed up cable. I am going to start retracing but it's still pretty cold outside.
 

NoGuru

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Jan 9, 2018
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Pretty sure I located the culprit. Does anyone know where this should be plugged into?
 

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