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Mustang/F150/Explorer CANBus Flex Fuel Installation Guide


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PCMTec Global CustomOS
FlexFuel Select Reference Guide

For CAN-Bus Connected Flex Fuel Sensor and CustomOS Configuration

The guide contains the BOM and installation reference guide for the PCMTEC CANBus Flex Fuel System. To obtain access to the guide please contact support with your vehicle information https://support.pcmtec.com

This guide is written for a RHD 18+ Gen 3 Mustang, however the general installation on Gen 2, LHD/RHD, Explorer, Focus, Maverick etc is the same. You will simply need to find an appropriate location to install the sensor.

You also do not have to use a OBD sandwitch plate and could simply wire directly into the HS1 CANBus network, we recommend utilizing a fuse tap at a minimum to easily disable the ECA2 if you hard wire directly into the CAN network. 2022+ vehicles with an SDLC will need to wire in behind the SDLC directly to the HS1 CANBus network.

We recommend utilising a fuel bypass for all return style fuel systems to ensure no flow restriction or interference with the fuel pressure regulation. On a return style system for lower power applications a bypass is not required but still recommended.

Example of a fuel bypass for the flex fuel sensor.


Example of a pre-wired kit for a RHD vehicle.


Example of a fuse tap installed to ensure the ECA2 only draws power when the vehicle accessories are on.


Example location of installation on the strut tower.



Video guide of how to use the Custom OS Wizard to build your own custom flex fuel logic.


Setup Notes:

There is delay/lag logic to lag the canbus ethanol signal to allow purging of the fuel lines post filter. Under CustomOS in the datalogger you will see ethanol raw and ethanol. If the engine is not running you will only see ethanol raw update. Once you start the engine it will slowly increase the ethanol to the measured value over approximately 5 minutes with the default filter.

If you wish to remove this filter (eg you have a return style fuel system) you can increase this value up to 1.0 (no filtering).
ID    Name    Value
auF100050    Flex Fuel High Pass Filter    0.005

However if you have a returnless system we recommend that you leave the lagged signal enabled and simply run the engine, this will ensure that spark is not added until the fuel lines/direct injection pump have been fully purged. The STFT will ensure that any fueling error is taken care of during this period. We found when testing on an 18 GT (with stock fuel system and DI) it takes approximately 10 minutes to purge the lines at idle, when driving it is purged within less than 1-2 minutes. We recommend that the first 10 minutes after a refill you do not drive WOT.

Note that the lag only occurs when the ethanol signal is increasing, when decreasing it drops back instantly to ensure that ignition timing is dropped to the 93 level immediately.

Alternatively you can simply unplug the canbus sensor (putting it into an error state) and manually set the ethanol content via the cruise control buttons using the following logic:

  • Engine off
  • Cruise control On
  • Cancel (tune select)
  • Cancel (ethanol select)
  • +/- to select ethanol on the speedo.

You can do this if you know the lines have already been purged. Then plug the sensor back in, this will manually disable the lagging of the sensor for that fill.

PCMTEC Flex Fuel Logic vs OEM

You can also piggy back off the OEM flex logic if you already have an OEM inferred flex fuel tune you want to use as a base. Note that we have not exclusively tested this method and recommend utilising the wizard to build your own custom logic with only the tables you require as this methodology has been tested on 100s of vehicles successfully.


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Flex fuel parameter files.zip

Attached is a set of parameter files which include the default Ford OEM FFV tables and scalars. Simply untick "values" and press load/append on the base alt tune.


You will then see many tables and scalars added


You will find that you can simplify your flex fuel logic dramatically by removing many of these and only adding the required tables.

Once you have completed building your flex logic in the wizard you will see new copies of the tables located here. These will be active in all tunes unless you have specified the same table/scalar in a tune slot. The PCM will then interpolate between the values in Base Fuel and High Fuel Tune 1 depending on ethanol content.



We have included an example 18 GT parameter file with the fueling tables used for cold start (please do not import the actual values as they will likely not be suitable for your vehicle), you can then add tables to add spark eg spark modifiers or simply use the cylinder pressure limit tables. Eg if the car is primarily going to be run on E85 you may be happy to simply use E85 torque and MBT tables and cap the spark via the max cylinder pressure spark limit. If you are going to be using various blends between E40-E70 you would likely want to add torque and MBT modifiers so that you get the maximum power without any torque errors at partial ethanol blends.


e85 cold start parameters.xml

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