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flex fuel

MoTeC M1 Software Tutorial

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I was going through sessions looking for a flex fuel function in MoTeC M1, but was not able to locate it. I searched again on the webinar and failed to find anything related. Do we have any reference on HPA on MoTeC M1 flex fuel function had been explained?


I think the M1 course was developed before the M1 multi-fuel support was added. Have you looked at the MoTeC Flex Fuel User Guide found here:


I'd read up on Motec's documentation as David suggested. It's pretty well explained, but if you still get stuck, let us know what specific question you have and we'll do our best to help.

Thank you guys for the reply.

I am attaching image of M1 configuration for the flex fuel with few questions.

On the first screenshot two tables I want to be clear about them.

first is the Alternative fuel Contribution Efficiency - do I need to adjust this table when using Alternative Fuel Mod as flex fuel or not?

Second Alternative fuel Compensation - how to go about it? is it a % of an overall fuel compensation? since I found some difference on fuel trim with I had the Ethanol 100 filled up my fuel tank the fuel trim was showing 10% increase so I adjust this table by 10 and there were no difference till I raised the number above 100.

Third question how important is to activate the fuel temp since when it was activate the reading was a bit out of scale so I decided not to activated. if it is important to be activated then that will lead to another question if I decide to calibrated manually.

On the sensor Calibration manual it works with plus width = ms, but in motec m1 the calibration are on V, so I was confused how to set it up correctly.

fourth question is about the fuel press so I assumed the fuel press reading will be through the same sensor already calibrated for the pump fuel no need to change anything the default value should be same and the regulator type would be Manifold Pressure Reference and the regulator ratio is 1.

Another question related to the flex fuel sensor, so when I install it. the reading showing 2.75% ethanol content although it was filled with pump gas and there is no way an ethanol is part of the fuel. the second observation was when I filled it with Ethanol 100 the reading was 102 to 103% ethanol content, so I decided to calibrated manually I the same issue I faced on the data sheet it works with hz and with Motec m1 it shows me V, so how to go about it. I hope the rest of the setting like the voltage reference are correct and the decode setting should be plus width or do I miss something?

last question related to injector flow correction on Motec Documents they shows primary and secondary and on my M1 firmware it shows only primary so how to adjust these setting and why I don't have the secondary injector flow correction or that works only when Alternative fuel mode is set to secondary fuel.

I believe I listed most of my questions hoping to find an answer for them and thank you in advance.

Attached Files

What firmware package are you using? Not all packages have support for secondary injectors.

What ethanol content sensor are trying to use?


Alternative Fuel Contribution Efficiency - Only used when Secondary Fuel is being used, this is a complete separate fuel system in the vehicle.

Alternative Fuel Compensation - Only needed if the other trims do not have a fine enough tuning range. I have only used this once in the 30+ vehicles that I have tuned using the M1 Alternative Fuel Functionality.

I always use the Fuel Temp from the sensor, why not? It's a free sensor input essentially. An example of the use of it is that I support a number of vehicles that do Tarmac rallies, these events often overnight in locations that are near or above the snow line so overnight temperatures will drop below 0 degrees. Having the fuel soak in these conditions also drops the density of the fuel by a large amount, leading to more fuel being injected for the same fuel pressure and injector duty. I have seen vehicles without a fuel temp input, that would normally idle at close to Lambda, idling at 0.8 or richer until the default Fuel temperature was changed to match the actual temperature of the fuel.

The standard calibration for the Continental sensors works accurately enough.

Use the settings in the document for the temperature, the selection of UDig Hybrid A or B changes the method that the M1 is using to read the Input, with the A channel being Frequency (0V = 0Hz, 5V = 5kHz) and B being Pulse Width (0V = 0ms, 5V = 5ms), This allows for both the Frequency and Pulse Width of the output from the Ethanol Content sensor to be read by a single pin.

The Alternative Fuel Pressure group is only read if the Alternative Fuel Mode is set to Secondary, this is not used when it is set to Flex Fuel.

The sensors themselves have a +/- of 2% last time I looked at the specifications, water in the fuel or air in the lines can also have an effect on the readings. If water is detected in the fuel in a large enough quantity, the Ethanol Content Sensor will report a frequency of 180Hz to signal this. Did you do a fuel sample check to ensure that the reported values where correct?

If you are using GPA (GP Lite doesn't have Alternative Fuel) then You only have Primary injectors, it is one of the points of difference between GPA and the higher Packages.

P.S. I wrote the M1 Flex Fuel document and did most of the development work.

I am using M130 GPR package July 2019 update and continental sensor.

Thanks BlackRex for your explanation the only thing left is the injector flow correction. Do I need to adjust the flow correction when using flex fuel mode? if I have to do so, then I assume the flow correction trim should be when the car is filled with Ethanol is that correct? if yes, then is it going to impact the fuel map when I revert back to pump gas?


The only time that you need to use the Fuel Injector Primary/Secondary Flow Correction is if there is a consistent change in the Lambda as the Ethanol Content increases, again, this is a correction that I have only used in two engines that where running a different blend of Ethanol that needed about 2% trimming.

The correction is applied as a sliding scale, so if the correction is set to 5%, then at E100 there will be a 5% increase, at E50 a 2.5% increase and E0 no increase.

Thank BlackRex for taking the time and explaining how the system works. Last question related to the alternative fuel compensation trim tables. On the package it show 100% and I believe the table could be expanded and use y and x axis as engine speed and load. By default the number is 100%, so shall I assume 100% no trims and 110% is an increase of 10% and 90% is -10%? is this how this compensation tables works?

The Compensation tables work with 0% being no trim, 10% being an extra 10%, -10% being 10% less. The base table should not have 100% in it.

Also, when you are using the Flex Fuel Option, the Alternative Fuel Properties Calibration has to be set to Ethanol, not E85. Setting it to E85 will make the blends scale between E0 and E85, rather than E100. This leads to E85 being treated as E72. Not as much of an issue when the fuel is actually E85, but in the transient areas you can be losing performance as you are not using all of the available properties for the fuel.

ok then when I filled with Ethanol 100 and the fuel type should be Eth.1 the trim should start with 0% and increase it when it is necessary across the rpm and load as required.

In most installations there should be no need to use the trims and compensations available for the Flex Fuel functionality.

alright thank Rex for the time.

Great job Stephen!

Just to tack one little thing onto what Stephen said, the system does work great and you'll end up with minimal fuel trims as ethanol shifts if all is well, but that does require your injectors match your injector data in M1 Tune.

If you're using an injector like an ID 1050XDS you're in great shape. If you're using an injector which does not have comprehensive accurate data modeling in M1 Tune, you'll be more likely to run into quirks like you found, which often relate to low pulse width non linearity not being accounted for in the injector model.

There is no reason that anyone should be using a non-characterized injector with a MoTeC M1 ECU. MoTeC dealers can send a sample injector through to MoTeC Australia, where their engineers (most likely Stephen Dean) will test it and create the necessary calibration. I've done this several times always worth the time it takes.

I completely agree David.

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