N54 Stock DME Flex Fuel

[langsbr]

The OTS maps are not really meant to run full E85. They interpolate correctly up to E50/60, and ALLOW use of up to E85 as a convenience by reducing boost target, etc, while keeping fuel maxed for higher blends. If you really want to run E0 - E85 / 100, you should get a custom tune.

Perhaps I am misunderstanding this comment, but isn't the entire point of flex fuel to ALLOW for running ANY ethanol blend? Sure, you might not get max performance with e85 if your fuel system can't deliver it, hence the interpolation breakpoint. I'm on a custom tune and while I could run E85, my fuel system is capped power wise around E40, so above that, boost target, et al, would be reduced.

I don't see why it being an OTS map or a custom tune would have any bearing on the functionality of flex fuel. If you are fuel limited, you are fuel limited, regardless of if it's an OTS tune or a custom tune, unless tuners now have magic to not need better LPFPs and supplemental HPFPs.

 

[Jake@MHD]

The OTS maps reduce load req after E50 or so fairly sharply / quickly. It was done to be safe as an OTS option. Sure you can run more, but it would be dumb as your car would be slower. A custom tune with a tuner they can better find the limits on your specific fuel system given it's age, etc.

It's the basic OTS vs. custom tune discussion, with added layers on top.

 

[langsbr]

I guess I got thrown when you said they "interpolate correctly" up to e60. It sounds as thought they are 'tuned' to e60, but then the interpolation aggressively reduces targets above that. I guess to me that is flex fuel doing exactly what it should, it's just not optimized over e60 on the ots maps.

 

[ajm8127]

@jyamona

Have you looked at programming the DME to read the sensor's output directly? Seems like that would be a more elegant solution than needing another box to convert the sensor's frequency output to an analog one. Then you convert that analog value read by the DME back to digital to use it in the logic. Why not just read the sensor directly? Does it come down to the functionality of the DME input? Does the analog input of the DME go to an ADC input pin on the TriCore part or is the ADC a separate chip?

I am not trying to take anything away from this accomplishment. Adding custom features like this to the DME is impressive. It just seems unnecessary to change the sensors output to an analog 0-5 V scale instead of using the DME to read the sensor directly. And it adds cost and complexity to the setup because you need to buy and wire in the Motiv or Fuel It flex fuel adapter.

 

[langsbr]

@jyamona

Have you looked at programming the DME to read the sensor's output directly? Seems like that would be a more elegant solution than needing another box to convert the sensor's frequency output to an analog one. Then you convert that analog value read by the DME back to digital to use it in the logic. Why not just read the sensor directly? Does it come down to the functionality of the DME input? Does the analog input of the DME go to an ADC input pin on the TriCore part or is the ADC a separate chip?

I am not trying to take anything away from this accomplishment. Adding custom features like this to the DME is impressive. It just seems unnecessary to change the sensors output to an analog 0-5 V scale instead of using the DME to read the sensor directly. And it adds cost and complexity to the setup because you need to buy and wire in the Motiv or Fuel It flex fuel adapter.

Since the output of the sensor is a digital frequency based one, my thought is that the DME doesn't have a useable digital input or processing power to convert that - thus, using the Motiv flex fuel box converts the frequency pulses to a DME useable 5V signal that can be used for flex fuel interpolation.

 

[ajm8127]

Since the output of the sensor is a digital frequency based one, my thought is that the DME doesn't have a useable digital input or processing power to convert that - thus, using the Motiv flex fuel box converts the frequency pulses to a DME useable 5V signal that can be used for flex fuel interpolation.

Sure, there are reasons why it might not be possible with the current hardware. The analog input could be low pass filtered at like 10 Hz or something that would make it impossible for a 50-150 Hz signal to get through. The analog input may go to an external ADC in which case changing the input type on the TriCore processor wouldn't be possible and the external ADC would need to be polled multiple times per second to sample the sensor waveform.

Perhaps the input was already an analog one and it was just easier to read an analog voltage value from it instead of re-configuring the pin.

I was just curious about the specifics.

 

[Jake@MHD]

Yep, pin used for input was already setup for analog voltage read. Additionally, it is polled / read in a 10ms routine, which would not give enough resolution to accurately sample 150Hz (or 180Hz error signal). It is not worth the effort to remap the pin and feed through the GPTA for frequency counting, etc.

Future DME will likely be CAN based for FF input, and support the Zeitronix ECA-2 CAN or similar.

 

[ajm8127]

Got it, thanks for sharing.

Future DME will likely be CAN based for FF input, and support the Zeitronix ECA-2 CAN or similar.

Will the analog input for FF still be supported?

 

[Jake@MHD]

It depends if the DME has pin availability. For example, the Euro DME that do not have DMTL seem unable to get the pin active.

 

[ajm8127]

It depends if the DME has pin availability. For example, the Euro DME that do not have DMTL seem unable to get the pin active.

Ok, I see. So older DME versions like MSD80 would support analog and more modern DME versions would support CAN.

 

[Jake@MHD]

Yea MSD8x will always support the current ECA input (analog voltage pin).

 

[tortue-xTz]

It depends if the DME has pin availability. For example, the Euro DME that do not have DMTL seem unable to get the pin active.

Hi, not sure if i totally understand this comment or if i'm misunderstanding (english is not my native language, i'm french), so i'll appreciate if thing could be cleared up :
i own an EU(german) 2009 335xi N54, and i'm trying to achieve Flexfuel with Motiv kit (ECA + sensor + engine-bay short lines).
The ECA voltage reading through MHD is constantly at 4.32V. I am trying to solve this with Jake from Motiv, but maybe we miss this DTML pin limitation for Euro DME ?
or i'm a just a fool that dont get the point ?

 

[Jake@MHD]

All msd8x DME work for flexfuel via the DMTL pin. That comment of mine above only relates to newer DME, like MEVD and beyond.

 

[Chris44]

View attachment 29685

https://datazap.me/u/marseille/mhd-...ctors?log=0&data=3-4-5-6-7-8-9-10-21-22-23-25

Hello, a question coming from a novice in tuning, the logs taken from your initial map (probably E40) without flex fuel installation shows more Boost/torque (18PSI/638Nm) than your Flexfuel map setup running E50 (17.89PSI/595Nm). How do you explain that? Were you not supposed to have more boost with E50 compared to E40? Thanks

 

[Mon54ster]

Do any of you guys have the required pin change diagram to succesfully run the MOTIV flex fuel kit on the n54 equipped E89? MOTIV emailed me telling me that I will have to change positions for a couple of pins on the module connector itself.

 

[NoQuarter]

@fmorelli had a diagram a long ways back I think.

 

[fmorelli]

@fmorelli had a diagram a long ways back I think.

E89 - 3DM Motorsport E89 Z4 Atacama Yellow Build

I think he is wondering if the output of the Bluetooth device is passing the ECA signal through to the flexfuel module. Given @jyamona says it doesn't work, I'm assuming there is something I don't know. I suspect he knows the Fuel-It setup, as it is probably the most common ECA config seen on...

bmw.spoolstreet.com

Filippo

 

[Mon54ster]

E89 - 3DM Motorsport E89 Z4 Atacama Yellow Build

I think he is wondering if the output of the Bluetooth device is passing the ECA signal through to the flexfuel module. Given @jyamona says it doesn't work, I'm assuming there is something I don't know. I suspect he knows the Fuel-It setup, as it is probably the most common ECA config seen on...

bmw.spoolstreet.com

Filippo

Indeed, I got that part done. Car works fine without the flex fuel box connected, as soon as I connect it back in I get codes related to the throttle body not being connected. So MOTIV emailed me this.

 

[Jake@MHD]

Indeed, I got that part done. Car works fine without the flex fuel box connected, as soon as I connect it back in I get codes related to the throttle body not being connected. So MOTIV emailed me this.

Yes, and they will need to tell you which pins to move. This is not a blanket change for all E89's (all MSD8x pinouts are the same). There was something swapped on that batch that needs to be fixed.

 

[Mon54ster]

Yes, and they will need to tell you which pins to move. This is not a blanket change for all E89's (all MSD8x pinouts are the same). There was something swapped on that batch that needs to be fixed.

Thanks for the info!