Flex Fuel/Dual Map Discussion

[mattman]

Hi, can anyone tell me the resistance value of the tuning pull up resistor to bring the continential flex fuel in line with the calibrations pcmtec have for the ford fg Barra?

The sensor manufacturer says the resistor isn't required but some Ecus may need it depending on the calibration table being used.

 

 

[Roland@pcmtec]

On 11/28/2019 at 3:30 PM, mattman said:

Hi, can anyone tell me the resistance value of the tuning pull up resistor to bring the continential flex fuel in line with the calibrations pcmtec have for the ford fg Barra?

The sensor manufacturer says the resistor isn't required but some Ecus may need it depending on the calibration table being used.

Not sure if you previously emailed us about this but I'll answer here anyway.

Basically you need frequency counter -> analog output voltage converter such as the innovate or zeitronix kit. You then need to step the voltage down to suit the analog input using a voltage divider. BF is 0.1-1.66v FG Mk2 (maybe some late Mk1s as well) are ~0-3.8v

You can't just average the frequency output with analog electronics as the sensor varies the frequency based on fuel temperature, then varies the pulse width based on ethanol %. Unless your fuel was a constant temperature it would not provide reliable results.

edit: Here are the specs of the sensor

50 Hertz indicates 0% ethanol, and
150 Hertz indicates 100% ethanol.
The pulse width indicates the fuel temperature. The normal pulse width is between 1 and 5 milliseconds:
1 millisecond indicates -40°C (-40°F), and
5 milliseconds indicates 125°C (257°F).

[XeAssert]

On 12/8/2019 at 1:14 PM, Roland@pcmtec said:

Not sure if you previously emailed us about this but I'll answer here anyway.

Basically you need frequency counter -> analog output voltage converter such as the innovate or zeitronix kit. You then need to step the voltage down to suit the analog input using a voltage divider. BF is 0.1-1.66v FG Mk2 (maybe some late Mk1s as well) are ~0-3.8v

You can't just average the frequency output with analog electronics as the sensor varies the frequency based on fuel temperature, then varies the pulse width based on ethanol %. Unless your fuel was a constant temperature it would not provide reliable results.

edit: Here are the specs of the sensor

50 Hertz indicates 0% ethanol, and
150 Hertz indicates 100% ethanol.
The pulse width indicates the fuel temperature. The normal pulse width is between 1 and 5 milliseconds:
1 millisecond indicates -40°C (-40°F), and
5 milliseconds indicates 125°C (257°F).

Hi,

What voltage divider would be used for a BA to use with the boost sensor input?

 

Thanks

[Roland@pcmtec]

4 hours ago, XeAssert said:

Hi,

What voltage divider would be used for a BA to use with the boost sensor input?

None. BA you can wire the 5v signal from the zeitronix/innovate converter straight in as its a 0-5v input.

[Roland@pcmtec]

Also if you use the Innovate flex converter you can rescale the output internally, so you don't need a voltage divider, you can just set the output to scale from 0 to 1.6v using LMProgrammer which is included with the Innovate LogWorks package (free to download).

https://www.innovatemotorsports.com/products/logworks.php

[Roland@pcmtec]

Someone was talking earlier about averaging out the PWM signal so I did a simulation. You would first need to step the voltage down to 1.6v using a voltage divider then build an RLC filter.

https://www.allaboutcircuits.com/technical-articles/low-pass-filter-a-pwm-signal-into-an-analog-voltage/

Can simulate here

https://www.multisim.com/create/

This helps you pick the RLC values

http://sim.okawa-denshi.jp/en/RLCtool.php

This shows that it would not be optimal. This is with a 50% duty (E50), you have a 7 second lag on startup to get a value that is close to the actual value. Then you have a 200mv ripple, the PCM could possible average this out but it wouldn't be great if you cranked the motor first go, you'd need to turn the ignition on for at least 3-4 seconds.

At cold temperatures the frequency drops to 0.2hz so you would have an even worse ripple as well.

So you might make it work, but I would not recommend this as a solution. The Innovate converter is a few hundred bucks, this would still cost you $5 in parts and a lot of time testing.

[Cameron]

So im strongly considering using a dry nitrous system on my fg turbo, primarily to bring my turbo on boost earlier, and im wondering how the fuel map can possibly be adjusted for fuel enrichment whilst using nitrous, and can it be done? Can i utilise a switch to have the system ready to use it, or is it not quite as simple? 

Im also utilising flex fuel, 

Thanks

[Roland@pcmtec]

You would need to do something like the following discussion here. Use Circuit 3 with the "high low" triggered from the nitrous circuit and a relay. 

 

 

[Cameron]

Ahh yes i see how you mean. 

In theory, could i utilise the two channel system and also retain adjustable boost control via steering wheel controls? Essentially one channel with variable boost control, and the other for nitrous system which is activated when armed? 

[Roland@pcmtec]

Let us know once you purchase the workshop edition and we can offer you more support. 

There is only a single analog input. Multi tune requires the factory dash and cruise control system. 

[WH47LS]

Hi there is there a write up on how to do the flex into ba xr6 turbo somewhere? I cant seem to find it 

[Roland@pcmtec]

On 5/26/2020 at 8:00 PM, WH47LS said:

Hi there is there a write up on how to do the flex into ba xr6 turbo somewhere? I cant seem to find it 

We haven't actually done a BA guide yet yet however the process is very similar for a BF/FG except for where the sensor is wired in. On the BA the flex fuel kit repurposes the turbo boost pressure sensor and uses the TMAP for boost sensor processing instead. The boost sensor min/max volts are then set out of range.

This means only BA turbo 6s are flex fuel supported, a turbo PCM must be used as the NA PCM lacks the boost sensor input driver.

To buy the kit speak to Danny at Pirotta Performance, he will have stock on the shelf ready to go.

https://www.facebook.com/pirottaperformance/