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Practical Diesel Tuning: What is Reflashing?

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What is Reflashing?


00:00 - In the past it's been common practice when we want to alter or optimise or modify the tune of an engine to replace the factory ECU with an aftermarket programmable unit such as the ones we've just discussed.
00:11 This type of tuning solution provides the tuner with complete control over the engine tuning parameters and changes can be made in real time via laptop tuning software.
00:20 As cars and engines have become more and more complex though, it's becoming more and more difficult to fit a standalone ECU.
00:27 And in the diesel tuning world, as we've mentioned, we also have less options available in terms of standalone ECUs that are capable of handling operation of high pressure fuel systems.
00:37 Even beyond the basics of running the engine it's really the integration of the ECU with the rest of the vehicle's electronic system that presents the real issue on modern cars and trucks.
00:46 It's quite common now for vehicles to have multiple ECUs controlling multiple aspects of operation including the engine, gearbox and ABS just to name a few.
00:55 And all these ECUs send information back and forth and communicate on the bus.
00:58 As you'd expect, in order for these modules to function properly, they rely on receiving the correct information from the engine computer.
01:07 When we replace this ECU with an aftermarket standalone ECU, the datastream will be missing and this might mean the rest of the vehicle doesn't operate correctly.
01:16 In many of the late model diesel vehicles that are popular for modification, we may have the option however to alter the maps stored inside the factory ECU.
01:24 This technique is known as reflashing.
01:27 Or often abbreviated as just reflashing or flash tuning.
01:30 The technique involves downloading the raw data out of the factory ECU through the OBD port, manipulating the required maps and then loading it or reflashing it back into the factory ECU.
01:42 Reflashing is an immensely powerful technique and allows the engine to be tuned in the same way the factory calibration engineers perform the task.
01:48 It's usually quite a cost effective option as well since we already have the ECU fitted to the car and there's no expense for a separate programmable ECU.
01:56 The other advantage is that we are usually dealing with an ECU that is designed and programmed with the single task of operating that specific engine and hence the available maps and the way the ECU operates can be very accurately tailored to the requirements of that engine.
02:11 This can often provide more seamless integration to the universal aftermarket ECU that needs to be adequately controlled and adjusted for a wide variety of universal fits.
02:20 When we download the maps out of an ECU, we will end up with a raw hexadecimal file or a ROM file.
02:27 That file won't make much sense on its own.
02:30 What we need is a piece of software that allows us to see and manipulate the various maps in a way that we're more familiar with.
02:36 This is achieved with what's referred to as a definition file.
02:39 You could think of a definition as the road map for the ECU's ROM file.
02:43 It tells tuning software what maps are available and where to find them in the ROM.
02:47 It also tells the ECU where it can find the data for the table axes.
02:51 With this in mind, the definition file is critical to being able to make changes to a factory ECU.
02:57 While finding the maps in the raw hex file is possible if you have the right skill set, it's beyond the scope of this course and we'll be assuming that you're working with a well developed accurate definition file from either a commercial or open source supplier.