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Practical Diesel Tuning: Tuning Modules

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Tuning Modules

02.59

00:00 - When it comes to tuning options for late model common rail diesel engines, one of the traditional choices has been a tuning module that's added into the existing ECU wiring with the aim of tricking the stock ECU into providing more power.
00:12 These are available from a variety of manufacturers and they vary in terms of quality and complexity and of course what sort of results you could expect from them.
00:20 This sort of tuning module typically offers either no end user tunability or very limited ability to make broad changes to the power output and for this reason they're not the focus of this course.
00:29 We believe that for the most part, these modules aren't able to provide the necessary level of control or refinement in order to achieve the results and reliability we need when tuning a diesel engine.
00:39 Despite this, we do know that these modules are popular and it's worth understanding what they are and how they function as you may come across a diesel engine you want to tune that already has one fitted.
00:49 In their simplest form, the most common method these modules use is to intercept the fuel pressure signal being sent to the ECU and manipulate it to trick the ECU into thinking the fuel pressure is lower than it actually is.
01:00 In turn, the ECU will then control the high pressure pump in order to increase the fuel pressure back to the desired target.
01:06 This manipulation has the effect of delivering more fuel than the stock tune would normally deliver, since the pulse width being delivered to the injectors remains the same, we now have more fuel pressure behind it.
01:16 The additional fuel of course results in the potential for more power.
01:20 However it's a relatively crude way of getting the desired result and one that doesn't allow for a lot of control.
01:25 It's important to know that these devices defeat the ECU's ability to meter fuel correctly which has a cascade effect often skewing fuel consumption metrics displayed to the driver, compromising predictive temperature safety backdowns which rely on fuel rate as an input and accelerating emissions system degradation as a result of excessive regenerations caused by an out of check air/fuel ratio.
01:47 More advanced modules may go further and also intercept and modify the injector pulse width and turbocharger control signals in order to increase boost and add fuel but we're still in a situation where we're tricking the stock ECU and this can be problematic.
02:00 As diesel engines have become more complex, the engine management systems have also advanced.
02:06 With this comes a range of sanity checks and limiters within the ECU that can affect the scope of what these modules can achieve without resulting in an ECU going into limp mode.
02:16 For example, if the reading from the mass airflow sensor doesn't correspond closely to what the ECU is calculating based on the parameters such as manifold pressure and engine speed, it's likely to suspect something's wrong.
02:27 Modern diesel ECUs also include an array of torque limits and torque limiters and if the ECU calculates that the current engine torque exceeds these values, then the potential advantage of any tuning module can quickly be eliminated by a limp home situation.