Ethanol & Flex Fuel Tuning: Introduction
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Introduction
03.04
| 00:00 | - When it comes to tuning a factory fitted ECU, our options for dealing with ethanol blended fuels and flex fuel get a little bit more complex. |
| 00:08 | Obviously there are ECUs that are designed from the outset to support flex fuel capability, but many don't have this sort of functionality. |
| 00:17 | That's not to say that you don't have any options if you're in this situation though. |
| 00:22 | Often if you're dealing with a car that's popular for modifying in the aftermarket you may have the ability to alter the way the ECU operates either through open source software code modifications or through commercial tuning software from the likes of COBB or EcuTek. |
| 00:39 | Tuning a factory ECU for flex fuel is very dependent on the particular ECU and is a little harder to cover in general terms, so in this section we're going to look at a simple approach for developing a dedicated ethanol tune for an ECU that doesn't offer any ethanol capability by design. |
| 00:59 | I'm not talking in this module about a flex fuel system therefore but rather just adjusting the tune for an ethanol blend. |
| 01:07 | You can utilise this approach to convert backwards and forwards between ethanol and gasoline by using two separate maps and reflashing them into the ECU to suit. |
| 01:18 | Of course the precautions we've already discussed regarding fuel contamination are very relevant for this approach. |
| 01:26 | While most aftermarket standalone ECUs work on the speed density principal and use a manifold absolute pressure sensor, the majority of factory ECUs are equipped with mass air flow meters where they directly measure the mass of air entering the engine. |
| 01:42 | Assuming that the MAF calibration is accurate, this means that the ECU can do a great job of accurately controlling the fuel delivery in order to achieve a specific target air fuel ratio. |
| 01:55 | Since the mass of air entering the engine is going to remain relatively fixed as we move from gasoline to ethanol fuel, the ECU is still going to have accurate data here from the MAF sensor. |
| 02:08 | Our job is to change the amount of fuel being delivered by the ECU to suit the blend of ethanol that we're using and there are a couple of options here. |
| 02:18 | In some instances the ECU may allow us to define the fuel characteristics such as the stoichiometric air fuel ratio which makes our job incredibly simple. |
| 02:28 | However in many cases the ECU is developed specifically to run on gasoline, and hence the fuel characteristics are hard coded into the ECU and can't be adjusted. |
| 02:39 | If we can't adjust the stoichiometric air fuel ratio, we're going to need to find another way of adjusting the fuel delivery which is to adjust the injector scaling data in the ECU instead. |
| 02:51 | Now that we have a basic understanding of how the factory ECU operates, we can move on and in the next module we'll discuss the tuning techniques that we can employ. |
