The term Ökotuning (English Eco-Tuning ) refers to the tuning of a car engine with the aim of reducing fuel consumption. Per chip tuning , the engine electronics of the vehicle modified so that the output characteristic is changed and a lower fuel consumption is achieved. Depending on the driving style, a significant reduction in fuel consumption can be achieved using eco-tuning .
Eco-tuning does not change the engine performance, but changes in driving behavior can be heard. In particular, so-called “comfort circuits” are changed, which lead to a sporty engine behavior due to short adjustment times, but at the expense of consumption. Some interventions of eco-tuning and its effects:
- Immediate onset of the overrun fuel cut-off in vehicles with gasoline engines : Many manufacturers do not activate the overrun fuel cut-off immediately when the accelerator is removed, but only after a few seconds, which leads to increased consumption. The reason for this lies in the exhaust gas behavior. During the overrun fuel cutoff, air is not moved through the exhaust gas aftertreatment system, but rather exhaust gas. After the end of an overrun fuel cutoff, increased NO x emissions can be expected for a short time due to the excess air in the 3-way catalytic converter . For this reason, most manufacturers only activate the overrun cut-off when longer overrun operation is to be expected.
- prevent the "Anfütterns" (only diesel engines ): First of all turbodiesel engines at low speeds and low load have the problem of having too little exhaust gas turbocharging for disposal. Long response times lead to a sluggish throttle response. For this reason, some manufacturers have opted for artificially increasing the exhaust gas pressure by means of a late injection in order to keep the turbocharger at speed.
- , Waiver / reduction of pre-injections, which were intended by the manufacturer to the: In diesel engines, nailing mitigate
- In the case of diesel engines: change in the injection times in the direction of lower fuel consumption at the expense of pollutant emissions (mainly NO x )
- Reduction of cold start enrichment (diesel), which ensures that the engine reaches operating temperature more quickly. This is not absolutely necessary for the engine, but it does lead to a faster response of the interior heating.
- Reduction / elimination of the additional injection processes which reduce load change reactions.
The main point of criticism is that it would not be necessary to adapt the maps if the drivers were to adapt their driving style to the characteristics of the engine. In mass tests , it was possible to achieve astonishing results with the so-called "normal Otto drivers" , but no or only slight reductions in consumption could be determined for drivers with a correspondingly fuel-efficient driving style - in some cases the eco-tuning was even counterproductive.
Most engines are deliberately not operated exactly at the best thermodynamic point, since nitrogen oxide emissions are too high there. In order to meet the legal NO x standards, a slightly higher fuel consumption (be) is accepted (this was observed when the three-way catalytic converter with lambda control was introduced: the enrichment of the mixture required to reduce pollutants under partial load led to a significant increase in fuel consumption). This measure is called the NOx-be trade-off . If the lambda target value is changed in order to achieve lower fuel consumption, the NO x emissions rise sharply. A modification with an increase in emissions is not permitted according to StVZO Paragraph 3; the operating license is no longer valid.