Flex Fuel System Overview

The Pro-M EFI Flex Fuel system is the only one on the market that allows you to easily make big power using E85, and to do it the right way.

To truly appreciate just how good the Pro-M EFI Flex Fuel System is, you need to compare the process necessary to set up a Flex Fuel system in any one of our competitor's products, to setting it up with Pro-M EFI. We encourage you to read through any and all of our competitors's manuals and watch their videos. To say that they make it difficult would be an understatement. With the Pro-M EFI system, all you do is turn on the Flex Fuel system in the software. You literally just enable the Flex Fuel system and Pro-M EFI does all the rest. This is explained in greater detail below.

The keys to this are not only our software, but also the Pro-M EFI Flex Fuel Sensor/Bypass Block assembly. This is the only Flex Fuel sensor assembly on the market that allows you to flow massive amounts of fuel through the sensor assembly so you can make real power. The other guys force you to come up with cumbersome and ineffective ways of using a Flex Fuel Sensor with a small 3/8” line, often on the return side, resulting in a system that works poorly at best.

The Pro-M EFI Flex Fuel Sensor/Bypass Block assembly is to be used on the feed side of the fuel system. It will accept up to a 10AN fitting and will outflow a -10 or 5/8” line. Installing the sensor on the feed side of your fuel system is the only way to ensure a steady and un-aerated supply of fuel to the sensor, allowing the sensor to take an accurate reading of the ethanol content of the fuel. The bypass passage in the assembly allows the portion of fuel that can't flow through the sensor to flow around the sensor. The passages in the block are designed in such a way that the sensor is ensured a steady flow of fuel, while still allowing an unrestricted flow of fuel through the assembly.

The Pro-M EFI Flex Fuel system allows you to use any blend of Gasoline and Ethanol you want, at any time, with no change to the fuel table, or any other change to the calibration at all! Stop at any station with any blend of gasoline and ethanol and head down the road. That's all there is too it!

In addition, if using our Progressive Water/Methanol Injection controls, the water/methanol injection system can be shut down automatically based on the ethanol content of your fuel, since the water/methanol is unnecessary when there is enough ethanol content in the fuel.

To program the Pro-M EFI PCM for the Flex Fuel system, simply enable the Flex Fuel System in your calibration file as shown below. No other change to any part of the calibration is needed. Not the fuel table, not the spark table... Nothing.


Flex Fuel System Configuration


Ethanol Content Spark Adder

Additionally, when using the Flex Fuel system described above, you also have the option of adding spark advance based on the ethanol content of the fuel. The “Flex Fuel Base Spark” table is a spark adder. The values in this table will be added to the values in the “Base Spark” table. You can add whatever amount of advance you want, at any location in the table you want, allowing you to completely customize the spark advance delivered to the engine when burning Ethanol, without making a single change to the base spark table.

The amount of advance added will be directly proportionate to the ethanol content of the fuel. In other words, if the fuel is 100% ethanol, you will get 100% of the spark adder. If 85% ethanol, you will get 85% of the spark adder. If 50% ethanol, you will get 50% of the spark adder. However, no spark is added below 11%, since most pump gas already contains 10% ethanol.

The ethanol content spark adder is shown below.


Ethanol Content Spark Adder

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