That's part of the reason why ECU flashing is much more common on cars than bikes incidentally: cars have, historically, had easier ways to connect to their ECUs than bikes. To wit, some method of connecting a computer or laptop to the ECU. Nowadays, we don't need UV lamps to reprogram memory chips (we use EEPROMs, or similar types of memory), but we do need some specialised kit. These were erased by 'flashing them' - physically exposing them to ultraviolet light, which reset all the internal memory components, allowing a new program to be installed onto the memory. It's called 'flashing', because in ye olden days, computers used EPROM (Erasable Programmable Read-Only Memory) chips. This means actually 'editing' the control programme that's on the bike's standard ECU, and uploading it into the memory. That brings us to the other method of fuelling tuning – re-flashing the ECU. The results are generally really good – a Power Commander gives great control over the fuelling on a bike engine, and can compensate for a wide range of engine tuning.īut there are limitations, and things you can't change so easily with a PC. Used with a Dynojet dyno and the control software, a tuner can quickly and easily alter the fuelling across the rev range, increasing or decreasing the amounts as needed, at all engine speeds, and across a range of throttle openings. These smart little boxes work by intercepting the injector signal from the engine's Electronic Control Unit (ECU), and changing the duration to suit, before passing it onto the injector. On bikes, the traditional way to alter this injector duration has been to use an aftermarket fuel injection computer, like the Dynojet Power Commander (PC). If you can alter the length of time that the engine's ECU opens the fuel injectors, you can change the amount of fuel put in at that point. On carburettors, that meant physically changing the jets: small brass tubes, with precise holes in them, that fed the fuel into the air flow. Change an exhaust, or airbox, alter the cam timing (or fit a turbocharger!), and chances are you'll need to alter the fuelling, so your engine gets the right amount of fuel to match the air flowing into the motor throughout the rev range. Modifying the fuelling on engines is an essential part of any tuning process. But what is ECU flashing? And how does it work? It's the latest in fuel-injection tuning, and they've been doing it with cars for years.