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Tuning Box illu

VS Engine Mapping

Following high demand of our customers we offer you here a complete description of the differences between diesel engine mapping and tuning boxes.


As a preamble please note that there are good and less good things about tuning boxes as well as engine mapping.

Tailor-made engine optimization

As you may know engine mapping consists of adjusting engine parameters that are obtained by reading original setup on processing unit.

This process enables easy adjustments of parameters and get the best (and the worst) out of the engine. Engine optimization is therefore not within anyone’s grasp. There might be quite many parameters to adjust in order to gain extra power as manufacturers include limits on pressure, torque … And this is why you cannot expect to systematically get the exact torque value you would wish. Torque model is not always made for the torque to be modified and it is often needed to reshape this model or bypass some protections.

Here again, there are a thousand ways to get certain power and torque levels by modifying only few or many parameters. This is what makes the different between competent and incompetent engineers. On diesel engines, skilled engineers would modify the injection advance, lambdas, injection duration, torque demand, rail pressure, turbo pressure and of course limiters (rail, pressure, torque, torque/speed, maximum speed) and even more. Same result can be obtained from either a rich injection program or a widely modified injection duration or even a high injected quantity/torque model. Impact of those two parameters will be a gain of power and torque.

You might wonder why it is necessary to adjust so many things while optimization can be achieved by only adjusting few parameters.

The reason is the following: the more parameters modified, the more homogenous the optimization will be. Vehicle will keep its attributes but driving pleasure increase is obvious just as you would own a higher range engine. Controlled linear torque increase, no fits and starts, no brutality. Those attributes will also help preserve engine’s original reliability. Technically, this will be translated by a reasonable injection duration, higher rail pressure for a better mixture (about 150bar), higher turbo pressure in order to decrease exhaust temperature and preserve particle filter, etc.

An unprofessional engine mapping might therefore end up as being equivalent or even worse than a tuning box bought on internet. 

Tuning box

By the way what is the box adjusting and why isn’t it as good as an engine mapping?

At first, be aware that a tuning box will cheat the probes and trick the values whilst mapping will modify values straight in the processing unit. 

Different kinds of tuning boxes

On Diesel engines worst boxes will connect on a temperature probe. Indeed catalyst warms quicker on low temperature and mapping delivers more fuel. Varying the temperature enhances more power (5% maximum). It only is a single 1€ resistor placed on the probe. This only gives low performances and impacts many other parameters resulting in a very approximate power feeling. Shortly, such box is strongly discouraged.

Second box type little more common connects on the injection rail. It will modify the probe and simulate a lack of pressure. Engine mapping will consequently counterbalance the artificial lack. Such technology is more reliable and gives pretty good results depending on vehicles. Although results seem satisfying adjusting pressure on the rail only does not deliver great driving feeling. And this is why driver feels the ON/OFF effect pretty hardly as the box does not manage to measure out the pressure to be delivered.

More recent boxes add another dimension by connecting to the camshaft probe measuring the engine speed. This smooth out the ON/OFF effect described here above and also gives different setups depending on the engine speed. Those boxes are a little more efficient and flexible.

Finally latest generation boxes (still dedicated to diesel engines) add another probe on the turbo. Adjusting turbo pressure on diesel engine does not engender greater performances but it helps reducing Exhaust gas temperature (EGT). Those boxes are equipped with three probes: camshaft, rail and turbo. Those are the most expensive and the most widespread boxes. Only by adjusting rail pressure such box achieve to satisfy drivers who are not too demanding. 

Is there any better tuning box solution ?

Yes. Instead of working on rail pressure, best solution would be to directly drive the injectors in order to precisely increase injection duration. However this would require to work under high-voltage while having total control on what is injected (right time and duration). In some cases this solution is more efficient but is harder to setup as it is riskier and much more expensive. And this is why such technology is almost never used by boxes manufacturers. 


Nowadays many solutions are available to get your vehicle more efficient. Customers face a wide range of brands, opinions, models and prices that eventually trouble their choice. Although we obviously recommend use of our mappings and ECU we do hope we taught you elementary knowledge on tuning boxes. The present article might better lead your choice towards optimization of your vehicle performances.