Motiv Flex Fuel Installation Guide

[NoGuru]

Is your flex fuel module the style that has a 2 piece harness? Can you just unplug the module from the harness and see if your codes persist? Has the flex fuel setup ever worked properly?

Yes, I can disconnect the entire module. I'll try that next. Yeah it worked fine for two years, then started giving wierd readings last September. Motive sent me a new wiring harness but that's were we are now.

I'm speaking in terms of physical state. If the problem is believed to be the hardware, isolate the hardware you expect to be bad otherwise it's just kind of speculation. I didn't mention how to properly isolate the box, simply because I don't know how the box works or what is needed for the DME to behave normally.

Yeah I know what you are saying but it's been installed for a few years and I am not even sure how to get it all the way back to stock but I can't really run that way since I have Aftermarket turbos, inlets, ect, that need the custom map to work, and BQ is out for a little while.

I just tried without the ground wire and same idle surging.

 

[NoGuru]

Also just unplugging the FF module creates the same thing, erratic idle when I start the car....

 

[doublespaces]

Also just unplugging the FF module creates the same thing, erratic idle when I start the car....

Okay, time to remove the wiring. If you still have the same problem then it's related to your car somehow. If the problem goes away, then it may be due to the contacts in your wires or something like that.

 

[matreyia]

I will flash back to my Base BQ map that is setup for FF and remove the ground wire and see what happens.

You should not do this. FF maps is for use with the FF module. It will not work without the module. If you disconnect the negative cable and have normal gas inside, then flash to stock and test run. If you have ethanol, then flash to proper ethanol MHD map after you disconnect negative module wire. Then test run.

If you do not know what percentage ethanol you have in the tank, then flash e60 MHD map non-FF and test run after disconnecting negative wire. Do this also if your tank is full of e85. Your symptoms are identical to mine when my module went kaputt. Voltage incorrect and all kinds of errors as you showed.

 

[NoGuru]

Uninstalled FF wiring and flashed back to stock, surging is still there. Must be something else causing this.

 

[NoGuru]

Reset Throttle, idle, and octane adaptations, turned car off for 30 seconds, turned on key and waited 30 seconds and started car, same issue.

 

[doublespaces]

That's good and bad news. At least now you can spend time researching the other possible causes for this, perhaps a new thread would be good.

 

[NoGuru]

Now that I have a new throttle body, back to the FF issue. Motive sent me a new module. When I install it, voltage reads above 4v and E content pegs at 100%.
With the old module plugged in, it reads around 1.5v and 25% E which is where it should be, until I floor it and it pegs to 100% E around 4.4v and stays there.

Is there maybe something I need to do to have the new module read correctly? I tired driving around and shutting off the car for a few minutes and restarting it but no change.

The only thing that has not been replaced in the FF system is the sensor. So I am leaning this way but wanted to know what your thoughts are?

 

[doublespaces]

4.0 volts and above is an error code. So the solution was a new throttle body?

 

[martymil]

Have you checked the e sensor is grounded properly, check the harness from the sensor to the ff module for damage.

That is like the 5th throttle body I seen/heard fail in the last month.

 

[NoGuru]

4.0 volts and above is an error code. So the solution was a new throttle body?

No, sorry for the confusion. The throttle body died at the same time this issue was going on. I got a used replacement throttle body but the FF issue is still present.

Have you checked the e sensor is grounded properly, check the harness from the sensor to the ff module for damage?

That is like the 5th throttle body I seen/heard fail in the last month.

I have changed the entire wire harness and the same thing persists. I will put some DeoxIT on the ground tomorrow and test.

 

[doublespaces]

I would completely remove the flex fuel wiring harness and get your car running normally without it before trying to troubleshoot the flex fuel further. Pardon me if that was already done.

 

[martymil]

One of the workshops I deal with had the same problem with a customers car, replaced the ff module and harness three times and gave up on it.

Removed the ff module and flashed to a non flex tune and all problems solved.

It was running properly for 6 months then it wouldn't, could not figure out the issue.

On a standalone tune it makes more power and no issues.

Exactly the same symptoms you have had.

 

[NoGuru]

I will give a little more insight. Car has had the Motive FF installed for about two years. Last fall it started to get these spikes in the readings and I have been working with Chris from Motive since then, although the car sat all winter. Fast forward to present and while I was trouble shooting the FF the throttle body died and I fully removed the FF wiring and module and flashed back to stock. Since then Motive have sent me a new module and wire harness that I installed and flashed back to my custom BQ FF tune.

The only part of the FF system that has not changed is the sensor that is part of the fuel line, so it could be that. But the strange part is why does the old FF module work until I go WOT then peg at 1oo% E and the new module just read 100% as soon as I plug it in.

 

[Jake@MHD]

Is the reading of the old ECA accurate before going WOT? Try the old ECA with the new harness, and also try the new ECA with the old harness.

I am not sure if you have PI or use that scaling feature, but for these tests I would hook it up in minimal fashion with only the required power and signal wire going to DME.

 

[NoGuru]

Is the reading of the old ECA accurate before going WOT? Try the old ECA with the new harness, and also try the new ECA with the old harness.

I am not sure if you have PI or use that scaling feature, but for these tests I would hook it up in minimal fashion with only the required power and signal wire going to DME.

Yep, I have tested both way's, new harness old module and vise versa. The old ECA is reading accurate until WOT.
I don't have Port injection installed yet because I am waiting until this gets resolved to install it.

 

[martymil]

The only thing you can do is change the sensor but I highly doubt it is the issue because the sensor only outputs one value
no matter where the throttle is.

Going of what I've seen it could be the new ff module too.

The only way to test it is pull one out of a car that has a flex setup 100% working and try your ff module in it and see if it misbehaves.

 

[NoGuru]

The only thing you can do is change the sensor but I highly doubt it is the issue because the sensor only outputs one value
no matter where the throttle is.

Going of what I've seen it could be the new ff module too.

The only way to test it is pull one out of a car that has a flex setup 100% working and try your ff module in it and see if it misbehaves.

I agree that the sensor seems unlikely, more just grasping at straws now.

That's a good idea to pull the module from a working car but I think I will have to wait for the stay at home ban to lift before finding someone.

 

[doublespaces]

Yep, I have tested both way's, new harness old module and vise versa. The old ECA is reading accurate until WOT.

Ah, so the idle issue was resolved, I missed that part: https://www.spoolstreet.com/threads/idle-surging.6226/

 

[martymil]

I agree that the sensor seems unlikely, more just grasping at straws now.

That's a good idea to pull the module from a working car but I think I will have to wait for the stay at home ban to lift before finding someone.

This is the problem now with fault finding, testing and development in my case as we are in a lock down, I have plenty
of projects i'm working on but cant finish.