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Article

Critical Concerns Regarding the Transition from E5 to E10 Gasoline in the European Union, Particularly in Poland in 2024—A Theoretical and Experimental Analysis of the Problem of Controlling the Air–Fuel Mixture Composition (AFR) and the λ Coefficient

by
Łukasz Warguła
1,*,
Bartosz Wieczorek
1,
Łukasz Gierz
1 and
Bolesław Karwat
2
1
Institute of Machine Design, Faculty of Mechanical Engineering, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
2
Faculty of Mechanical Engineering and Robotics, AGH University of Krakow, A. Mickiewicza 30, 30-059 Krakow, Poland
*
Author to whom correspondence should be addressed.
Energies 2025, 18(4), 852; https://doi.org/10.3390/en18040852
Submission received: 31 December 2024 / Revised: 3 February 2025 / Accepted: 7 February 2025 / Published: 11 February 2025
(This article belongs to the Special Issue Advancements in Ignition Engine Technology: From Combustion Efficiency to Emission Reduction)
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Abstract

:
The RED II Directive requires European Union member states to increase the share of renewable energy in the transport sector to at least 14% by 2030. In January 2024, Poland replaced E5 gasoline (95 octane) with E10, which contains up to 10% bioethanol derived from second-generation sources such as agricultural residues. The transition to E10 raises concerns about the ability of engine management systems to adapt to its different air–fuel ratio (AFR) requirements. The AFR for E10 (13.82) is 1.98% lower than for E5 (14.25) and 3.88% lower than for pure gasoline (14.7). Research conducted on a spark-ignition engine (with AFR regulation) using an exhaust gas analyzer demonstrated that during the combustion of E5 and E10 fuels with correctly adjusted AFR and operation at λ = 1, the use of E10 potentially increases CO2 and NOx emissions despite reductions in CO and HC. However, when calibrated for E5 and operated with E10 fuel, an increase in CO2 and HC concentrations in the exhaust gases is observed, along with a reduction in CO and NOx. This phenomenon is attributed to operation with lean mixtures, at λ = 1.02. This study investigates both the theoretical and experimental impact of this fuel transition. Fuel systems typically adjust engine operation based on exhaust gas analysis but cannot recognize fuel type, leading to incorrect λ values when the AFR differs from the ECU’s programming. Effective adaptation would require additional fuel composition sensors and editable ECU mappings. For older vehicles or small non-road engines, manual adjustments to injection or carburetor systems may be necessary.

1. Introduction

The use of alternative fuels in internal combustion engines is crucial for several reasons, encompassing environmental [1], economic [2], and technological aspects [3]. Key motivations include environmental protection [4,5], reducing dependence on fossil fuels [6], promoting sustainable development [7], meeting European Union regulations [8], leveraging technological capabilities [9], and enhancing cost-efficiency [10,11].
Traditional fossil fuels, such as gasoline and diesel, contribute significantly to carbon dioxide (CO2) emissions, a major greenhouse gas. Alternative fuels like bioethanol [12,13], biodiesel [14], and hydrogen [15] emit considerably less CO2 over their lifecycle [16,17]. Using alternatives, such as biofuels, natural gas, hydrogen, or e-fuels, reduces dependency on imported crude oil from a limited number of countries [18]. Domestic biofuel production and advancements in renewable energy technologies enable nations to mitigate global oil price fluctuations [19]. Biofuel production often relies on waste materials, such as used cooking oils [20], agricultural residues [21], or biomass [22]. Additionally, alternative fuels, such as bioethanol or biodiesel [23], are derived from renewable resources, which can be produced sustainably, supporting agriculture and local economies.
The European Union’s climate neutrality goals, including initiatives like “Fit for 55” [24] and the “European Green Deal” [25] require the transport sector to reduce emissions and increase renewable fuel use. Automotive manufacturers are mandated to lower fleet-wide CO2 emissions, fostering the development of alternative propulsion technologies and low-emission fuels. Modern technologies allow vehicles to utilize various alternative fuels, such as flex-fuel vehicles [26] capable of running on gasoline–bioethanol blends. Hydrogen, e-fuels, and biomethane are becoming increasingly viable due to infrastructure development and decreasing production costs. The adoption of alternative fuels also drives industrial growth and job creation in renewable energy sectors. Among the most common alternative fuels for spark-ignition engines are bioethanol blends, such as E10 and E85 [27,28].
Alternative fuels address challenges related to environmental protection, energy security, and sustainable transport development, forming a critical component of the transition to a low-emission economy, particularly in the context of global climate policies. However, their implementation must consider both newly manufactured vehicles and existing ones. Many vehicles currently on the market were designed for fuels without bioethanol additives or with only 5% blends (E5) [29,30]. Introducing regulations that abruptly replace previously available fuels may negatively impact existing engine designs and disrupt air–fuel mixture control processes in vehicles calibrated for other fuel types [31].
Most vehicles and combustion-powered machines regulate combustion using algorithms based on the air–fuel ratio (AFR). However, the λ coefficient used to control AFR is fuel-dependent. While λ is a universal indicator for various fuels, AFR varies with fuel composition (e.g., stoichiometric AFR for E10 is ~14.1, compared to 14.7 for pure gasoline). Lambda sensors in engine control systems regulate the air–fuel mixture and optimize combustion, but changing fuel composition can disrupt engine performance if not properly calibrated for the new AFR.
A review of the literature, combined with knowledge of AFR control processes in internal combustion engines and the fuel regulation changes in the EU effective from 2024 (e.g., in Poland), highlights the need for analyzing the impact of E10 fuel on air–fuel mixture control in vehicles designed for E5 or pure gasoline. This issue affects all vehicles produced before 2023, as λ control systems must be calibrated for E10 due to the replacement of E5. This article analyzes the regulatory changes regarding fuels in the EU, fuel differences, λ control methods in vehicles, and risks of improper emissions due to incorrect λ control, and it provides recommendations for improving the current state. Additionally, the experimental impact of this fuel transition was investigated, with a focus on confirming the risks of improper emissions resulting from incorrect λ control.

2. Theoretical Analysis

2.1. Regulations Introducing E10 Fuels in the EU

Since 1 January 2024, Poland has implemented changes in fuel availability at gas stations, replacing E5 gasoline with E10 gasoline. E10 contains up to 10% bioethanol, whereas E5 contains a maximum of 5%. This change aligns with EU regulations aimed at increasing the share of renewable energy sources in transportation and reducing CO2 emissions. Poland became the 18th country in the European Union to introduce E10 fuel, following countries such as Austria, Belgium, Bulgaria, Denmark, Estonia, Finland, France, the Netherlands, Spain, Ireland, Lithuania, Latvia, Luxembourg, Germany, Romania, Slovakia, and Hungary. Additionally, E10 is also available in countries like the United Kingdom and Norway.
The introduction of E10 gasoline is rooted in EU directives, particularly Directive (EU) 2018/2001 of the European Parliament and Council (RED II) of 11 December 2018, on the promotion of renewable energy sources. This directive requires member states to increase the share of renewable energy in the transport sector to at least 14% by 2030, mandating greater use of bio-components, such as bioethanol, in transport fuels. Directive 98/70/EC (as amended) on fuel quality specifies the limits for bio-component content in fuels, including up to 10% bioethanol for E10. Commission Delegated Regulation (EU) 2019/807 of 13 March 2019 complements RED II by defining criteria for biofuels, bio-liquids, and fossil fuels in the context of sustainability.
Poland introduced E10 as part of its efforts to meet EU environmental and sustainability goals. E10 has been gradually adopted in other countries, starting in France in 2009, Germany and Finland in 2011, Belgium in 2017, the Netherlands in 2019, Slovakia and Hungary in 2020, the United Kingdom in 2021, and Lithuania and Ireland in 2023.
In 2011, a similar transition occurred when E5 gasoline replaced 95-octane gasoline without bio-additives. The primary goal was to increase the share of renewable energy in transportation and reduce greenhouse gas emissions. The legal framework for introducing E5 was Directive 2009/28/EC (RED I) of 23 April 2009, which promoted renewable energy use, including increased biofuel shares in transport. Directive 98/70/EC (on fuel quality), as amended, regulated the allowable parameters for fuels, including the maximum bioethanol content in E5 gasoline.
The impact of these fuels on AFR control was not analyzed at the time and will be examined in this article.

2.2. Lambda (λ) Control at Different AFR Values Resulting from Fuel Changes

Lambda (λ) control in internal combustion engines depending on AFR (air–fuel ratio) values during fuel changes (gasoline 95, E5, E10): Lambda (λ) control in internal combustion engines is based on chemical stoichiometry principles and engine adjustments to fuel composition. The λ coefficient, where λ = 1, represents the stoichiometric air–fuel ratio, which is ideal for catalytic converters used in exhaust purification and combustion when running on gasoline. However, operating conditions [32] such as vehicle acceleration [33], startup [34], engine braking, or fuel-efficient driving result in mixtures where λ > 1 (lean mixture: more air, less fuel) or λ < 1 (rich mixture: less air, more fuel). The stoichiometric ratio depends on the type of fuel, as different fuels have varying chemical-mixture requirements.
The stoichiometric AFR differs for fuel types depending on their chemical composition. For gasoline 95, composed entirely of hydrocarbons, the AFR is 14.7:1, meaning 14.7 parts of air are required to combust one part of fuel. The air–fuel ratio (AFR) for a given fuel can be calculated using the stoichiometric combustion reaction. For gasoline (95), which is primarily a mixture of hydrocarbons, we approximate its chemical formula as CnHm (e.g., C8H1 8 for octane). The stoichiometric combustion reaction is as follows (1):
C n H m + n + m 4 O 2 → n C O 2 + m 2 H 2 O
where
  • n—number of carbon atoms in the fuel molecule,
  • m—number of hydrogen atoms in the fuel molecule.
The air required for complete combustion is derived from the oxygen demand, considering that air contains about 21% oxygen by volume (or 23.2% by mass). The equation for the stoichiometric AFR is as follows (2):
A F R = M a i r M f u e l
where
  • M a i r —molar mass of air (approximately 28.97 g/mol),
  • M f u e l —molar mass of the fuel CnHm (calculated from its composition).
Substituting for the oxygen content (3):
A F R = 4.76 · n + m 4 M a i r M f u e l
where the air-to-oxygen ratio by volume 4.76.
For gasoline approximated as octane (C8H18), n = 8, m = 19, Mfuel = 114.22 g/mol. Substitute these values to compute the AFR for gasoline 95 (4):
A F R = 4.76 · 8 + 18 4 · 28.97 114.22 ≈ 14.7
This is the typical stoichiometric AFR for gasoline 95.
For E5 fuel, which contains 5% bioethanol, the AFR is approximately 14.25:1 due to the oxygen present in bioethanol. To calculate the air–fuel ratio for E5 fuel, we consider it to be a mixture containing 95% gasoline (assumed as C8H1 8, octane) and 5% ethanol (C2H6O). For a mixture, the AFR is weighted by the proportions of each component (5):
A F R E 5 = 1 ω g a s o l i n e A F R g a s o l i n e + ω e t h a n o l A F R e t h a n o l
where
  • ωgasoline—mass fraction of gasoline in the fuel (0.95 for E5),
  • ωethanol—mass fraction of ethanol in the fuel (0.05 for E5),
  • AFRgasoline—AFR for pure gasoline (14.7),
  • AFRethanol—AFR for pure ethanol (9.0).
Substitute the values (6):
A F R E 5 = 1 0.95 14.7 + 0.05 9.0 ≈ 14.25
Thus, the stoichiometric AFR for E5 is approximately 14.25:1.
E10 fuel, with 10% bioethanol content, has an even lower AFR of about 13.82:1, reflecting the higher oxygen content that reduces the required air for combustion.
The change in AFR across different fuels arises from their chemical composition and bio-component content. Gasoline 95 consists entirely of hydrocarbons, requiring a 14.7:1 air-to-fuel ratio for combustion. In contrast, the presence of bioethanol (C2H6O) in E5 and E10 reduces the required oxygen from air, as the oxygen in bioethanol participates in the combustion process, lowering the AFR and necessitating adjustments by engine control systems.
The engine control unit (ECU) compensates for fuel composition changes to maintain a λ value close to 1, critical for optimal catalytic converter performance and minimal emissions. This process relies on oxygen (lambda) sensors, which monitor oxygen levels in exhaust gases and relay data to the ECU, indicating whether the air–fuel mixture is rich (λ < 1) or lean (λ > 1). Based on these data, the ECU adjusts the mixture proportions, ensuring efficiency and compliance with emission standards.
The ECU should adjust fuel injection according to the type of fuel to maintain λ = 1. For gasoline 95, the AFR is 14.7:1, ensuring the optimal stoichiometric mixture. With E5 fuel, containing 5% bioethanol, the mixture would be slightly leaner (λ > 1) at the same fuel dose, requiring the ECU to increase fuel injection and lower the AFR to approximately 14.25:1. For E10, with 10% bioethanol, an even greater adjustment is needed, as the AFR for λ = 1 is about 13.8:1, necessitating further fuel injection to maintain optimal combustion conditions.
Engines do not “recognize” the fuel type in terms of direct composition analysis unless equipped with fuel composition sensors, which are rare. Instead, modern engines adjust fuel dosage based on the λ coefficient without explicitly distinguishing between gasoline 95, E5, or E10. The lambda sensor measures oxygen levels in exhaust gases, indirectly indicating whether the mixture is rich or lean, without identifying the fuel type.
When switching fuel types (e.g., from E5 to E10), the ECU does not identify this as a fuel change but as a deviation from the expected stoichiometric mixture. The higher oxygen content in bioethanol in fuels like E10 initially results in “leaner” exhaust readings (λ > 1). The ECU responds by increasing fuel injection to restore λ = 1. For the ECU, this is a standard reaction to lambda sensor signals, regardless of whether the change is due to different fuel, injection system issues, or another cause.
The conclusion is that the system does not directly recognize the fuel type but adjusts its operation based on exhaust gas analysis to maintain the correct air–fuel ratio in real time. However, if the fuel has a different AFR than programmed into the ECU, the system strives for a λ value that may not be optimal. Proper fuel differentiation would require additional sensors and editable injection mapping in the ECU or adjustable settings in mechanical carburetor systems.
The differences in λ and stoichiometric AFR values illustrate how fuel type impacts air–fuel ratio requirements and the necessity for adjustments by the engine control system. For example, for gasoline 95, the stoichiometric AFR is 14.7:1 at λ = 1, decreasing to 13.2:1 at λ = 0.9 (rich mixture) and increasing to 16.2:1 at λ = 1.1 (lean mixture). For E5, the AFR is about 14.25:1 at λ = 1, 12.7:1 at λ = 0.9, and 15.5:1 at λ = 1.1. For E10, due to its higher bioethanol content, the AFR is lower at 13.82:1 at λ = 1, 12.4:1 at λ = 0.9, and 15.2:1 at λ = 1.1. These variations highlight the impact of fuel composition on mixture parameters and the adjustments required by engine control systems.
Engines not equipped with fuel composition sensors or flexible injection maps may not fully adapt to fuel changes, leading to operation with a suboptimal stoichiometric mixture. For fuels like E5 or E10, which contain bioethanol, higher fuel doses are required to compensate for the lower AFR. For example, at λ = 0.9, the AFR decreases to 13.2:1 for gasoline 95, 12.7:1 for E5, and 12.4:1 for E10, illustrating the effect of fuel composition on engine adjustments. The conclusion is that while the ECU aims to maintain λ = 1, it does not distinguish the fuel type and instead reacts to exhaust gas changes, potentially leading to inaccuracies when using fuels with different chemical compositions than those for which the system was initially calibrated.

2.3. The Importance of Fuel Change Without Adjusting the Stoichiometric Air–Fuel Ratio (AFR) in the ECU Control Process and Its Correlation with Improper Exhaust Emissions

Changes in the composition of fuels such as gasoline 95, E5, and E10 are significant for both engine operation and exhaust emissions. The addition of bioethanol in E5 (5%) and E10 (10%) fuels alters the stoichiometric air–fuel ratio (AFR), influencing combustion behavior and necessitating adjustments to engine parameters. Ethanol reduces the AFR because it contains oxygen in its chemical structure, meaning less air is required for proper combustion compared to gasoline 95.
Improper adjustment of the air–fuel mixture can lead to several risks related to emissions. A lean mixture (λ > 1) increases nitrogen oxide (NOx) emissions, which are harmful to health and contribute to smog formation. Conversely, a rich mixture (λ < 1) results in higher emissions of particulate matter (PM), hydrocarbons (HC), and carbon monoxide (CO), all of which negatively affect the environment and human health. Prolonged operation with an improper mixture can also damage the catalytic converter [35], further deteriorating exhaust quality. Figure 1 illustrates the theoretical relationship between exhaust emissions and air–fuel mixture composition, as presented by Herner and Riehl in 2013 [36]. Based on this analysis, it is shown that when the engine is calibrated for E10 fuel, the λ coefficient is correctly regulated at λ = 1. However, when the engine is calibrated for E5 but operates on E10, the ECU aims for λ = 1 but instead achieves λ = 1.022. Similarly, when the engine is calibrated for gasoline 95 but operates on E10, the ECU targets λ = 1 but achieves λ = 1.065. Finally, when the engine is calibrated for gasoline 95 but operates on E5, the ECU also targets λ = 1 but achieves λ = 1.045.
The range of lambda regulation under real operating conditions covers a broader spectrum than the ideal λ value, typically oscillating between λ = 0.9 for rich mixtures and λ = 1.1 for lean mixtures. Incorrect air–fuel mixture control caused by a fuel change is illustrated in Figure 2. The changes shown there demonstrate even more significant negative effects on air pollution and improper air–fuel mixture selection.
Operating a spark-ignition (SI) engine on lean mixtures (λ > 1) poses several risks that can affect engine performance [37], durability, and emissions. Lean mixtures result in higher combustion temperatures, which promote the formation of NOx, harmful pollutants that contribute to respiratory illnesses, smog, and greenhouse effects [38]. The increased temperature can also lead to engine overheating, causing damage to pistons, valves, and cylinder heads, as well as cracking of exhaust valves and other heat-exposed components [39]. Additionally, the risk of knock (pre-ignition or detonation) increases under these conditions, potentially damaging pistons, piston rings, and bearings. Lean mixtures reduce the effectiveness of catalytic converters [40], which are designed to operate optimally at a stoichiometric mixture (λ = 1), and prolonged operation can lead to overheating and degradation of the converter, diminishing its ability to reduce CO, HC, and NOx emissions [41]. Furthermore, the reduced fuel proportion in lean mixtures lowers the energy released during combustion, resulting in decreased engine power and torque, impacting vehicle performance [42]. High combustion temperatures can degrade lubricating oil, reducing its protective properties and accelerating wear on pistons, cylinders, and bearings [43]. Starting difficulties and unstable idle operation are also common with lean mixtures, as insufficient fuel can hinder proper ignition, particularly in cold conditions. Additionally, incomplete combustion can lead to deposits forming in the combustion chamber [44], on valves, and on spark plugs, disrupting airflow and reducing efficiency. Lean mixtures also place additional strain on spark plugs, causing faster wear or fouling of the electrodes [45]. In turbocharged engines, excess air and high temperatures may cause soot buildup in the turbocharger [46,47], reducing boost efficiency and increasing the risk of damage. Proper calibration of the engine’s AFR by the ECU is critical to prevent these issues, maintain optimal performance, and minimize environmental impact.
Older vehicles not designed for fuels with higher bioethanol content, such as E10, face greater risks because their fuel injection systems and control technologies may not adapt appropriately to changes in AFR (e.g., through a limited range of regulation [48]). This can lead to incorrect engine operation, increased emissions, and reduced engine efficiency and longevity. Thus, fuel-composition changes emphasize the need for appropriate engine technology adaptations to ensure proper combustion and minimize environmental impact.
While the risks mentioned above are less commonly cited, other widespread concerns associated with using E10 in older engine designs include accelerated corrosion of metal fuel system components, particularly aluminum parts [49]. Additionally, ethanol can degrade rubber components such as seals and hoses, increasing the risk of fuel system leaks and failures [50].

2.4. Recommendations for Correcting Lambda Sensor Signals in Emulators or Controllers in Systems Modifying Signals for the ECU

Devices that modify the signal from lambda sensors (e.g., emulators or controllers in systems that adjust the signal for the ECU) need to be properly calibrated for E10 fuels. This requires modifications toward a richer mixture (Figure 3). This adjustment allows for an increase in fuel dosage and the achievement of the correct stoichiometric composition or another desired value (within the expected range).
Emulation of lambda signals involves generating a modified output from the lambda sensor that the ECU interprets to adjust fuel injection and ignition timing. This process is particularly critical when transitioning to fuels like E10, as the stoichiometric AFR for E10 (13.8) is lower than that of E5 (14.1) or gasoline 95 (14.7). Without proper emulation, the ECU may incorrectly target a lambda value unsuitable for the fuel in use, resulting in lean or rich mixtures that negatively impact combustion efficiency, emissions, and engine performance. Modern lambda signal emulators must dynamically adjust the signal to reflect the optimal mixture for E10, ensuring the ECU perceives the correct air–fuel ratio. For instance, if the engine control system is calibrated for E5, the emulator should alter the signal to approximate λ = 0.98 for E10, which would result in the actual lambda (λ actual) being adjusted to λ = 1. This ensures that the engine operates within the desired parameters for efficiency and emission control. Figure 3 demonstrates the required corrections for different lambda values based on the fuel type and the original calibration of the ECU. It also highlights the role of the flue-gas treatment system (three-way catalytic system) in optimizing emissions under these conditions. The scenarios presented (a–d) show varying lambda coefficients (λ = 1, 0.98, 0.94, and 0.96) and their corresponding control ranges, illustrating the relationship between signal emulation and fuel-type compatibility. Emulators must ensure precision in the modified lambda signal to prevent misinterpretation by the ECU, as such misinterpretation could lead to deviations from the optimal AFR. Advanced emulation systems utilize real-time feedback from wideband sensors to dynamically adjust the signal. After installing or adjusting emulation systems, thorough testing under various operating conditions is crucial to verify that the actual lambda value aligns with the target and that emissions remain within acceptable limits. By integrating emulation techniques with precise lambda correction, it is possible to ensure that engines perform optimally with E10 fuels, maintaining a balance between efficiency and compliance with environmental standards.

2.5. The Number of Vehicles Potentially Unsuitable for E10 Fuel in Poland

As of the end of 2023, there were 27.2 million registered passenger cars in Poland, representing the primary group of vehicles equipped with spark-ignition engines for which E10 fuel is intended. However, many of these vehicles were introduced to the market at a time when only gasoline 95 or E5 fuel was widely available at fuel stations. Consequently, the AFR systems in these vehicles were likely calibrated for these older fuel types, and their engine control units may not be optimized for E10 fuel.
This issue extends beyond passenger vehicles to include non-road small engines, such as those used in lawn mowers, chainsaws, and other portable machinery. These engines often lack sophisticated fuel management systems capable of adapting to the different stoichiometric AFR of E10, making them particularly vulnerable to operational inefficiencies and damage. The use of E10 in such engines could lead to issues like overheating, increased emissions, or even mechanical failure over time.
In countries that have only recently implemented regulations requiring the use of E10 fuel, a significant proportion of vehicles on the road are at risk of improper engine operation. This is especially true for older vehicle models and machinery that were manufactured with AFR calibrations for pure gasoline (95) or E5, and do not have the capability to automatically adapt to fuels with higher ethanol content.
The challenge is particularly pronounced in countries with a large fleet of aging vehicles. In these markets, vehicles are often kept in use for extended periods, and retrofitting or upgrading their fuel systems to accommodate E10 is not always economically viable. As a result, a substantial number of vehicles may experience problems such as poor fuel economy, increased emissions, or engine knocking when using E10 fuel.

3. Experimental Analysis

3.1. Materials and Methods

The study was conducted using a Honda GX390 (licensed by the American Honda Motor Company, Inc., Torrance, CA, USA) SI engine. The engine’s specifications are detailed in Table 1. This engine allows for straightforward mechanical adjustment of the AFR. Only E5 and E10 fuels were utilized in the experiments, as 95-octane fuel without ethanol is no longer available in Poland; the characteristics of these fuels are presented in Table 2. To analyze the concentrations of exhaust gases—CO, CO2, HC, and NOx—and to determine the lambda (λ) value, a Capelec CAP3201 (Montpellier, France) exhaust gas analyzer was employed. The technical specifications of this device are provided in Table 3. The experiments were performed with the engine operating at an idle speed of 3600 rpm. The study was conducted in three variants (Figure 4). The first involved operating with the AFR properly adjusted for the tested fuels, E5 and E10 (with a λ value of 1). The second variant involved adjusting the AFR correctly for E5 fuel but fueling the engine with both E5 and E10 (resulting in improper operation on E10, with the λ value equal to 1 only for E5). The third variant involved adjusting the AFR correctly for E10 fuel but fueling the engine with both E5 and E10 (resulting in improper operation on E5, with the λ value equal to 1 only for E10).
In analyzing the measurement error, the arithmetic mean was used as the estimator of the desired value, and the confidence interval was calculated with a confidence level of p = 0.05. Statistical analysis was performed according to procedures appropriate for the normal distribution of the measured data points.

3.2. Results and Analysis

The study results present the concentrations of exhaust gases CO, CO2, HC, and NOx during engine operation with varying lambda coefficient adjustments and different types of fuel (E5 or E10). A comparison of E5 and E10 fuels is illustrated in Figure 5, with optimal lambda coefficient regulation for the selected fuels. It can be observed that under proper λ regulation, the use of E10 fuel reduces CO and HC concentrations while increasing CO2 and NOx levels. The reduction in CO and HC concentrations is attributed to ethanol, which contains oxygen in its molecular structure, facilitating more complete combustion of the fuel mixture. As a result, CO and HC emissions in the exhaust gases are reduced. However, the higher ethanol content in the fuel can lead to increased combustion temperatures, promoting the formation of NOx. Ethanol contains fewer carbon atoms per molecule compared to gasoline, which theoretically should result in lower CO2 emissions. In practice, however, due to the lower energy density of ethanol, engines consume more E10 fuel, which may lead to a slight increase in CO2 emissions.
The comparison of E5 and E10 fuels, with proper lambda (λ) coefficient regulation applied exclusively for E5 fuel, is presented in Figure 6. The engine control settings optimized for E5 fuel, when used with E10 fuel, resulted in lean mixture operation, corresponding to λ = 1.02 for E10. This adjustment led to a 14.2% reduction in CO concentration and a 4.4% reduction in NOx, accompanied by an increase in CO2 by 2.1% and HC by 3.7%. In conventional 95-octane gasoline, lean mixtures typically result in increased NOx emissions and reduced CO and HC concentrations, and they may contribute to lower fuel consumption, which is reflected in reduced CO2 emissions. However, E10 fuel contains a higher proportion of ethanol, which induces changes in the combustion process and pollutant emissions. Ethanol, as a component of E10 fuel, contains oxygen within its molecular structure, improving combustion efficiency. Under lean mixture conditions (λ = 1.02), the availability of oxygen in the fuel facilitates more complete hydrocarbon oxidation, leading to a reduction in carbon monoxide (CO) emissions. During ethanol combustion in E10 fuel, more carbon is oxidized to carbon dioxide (CO2), especially under lean mixture conditions, where oxygen availability is increased. Furthermore, the lower energy density of E10 results in higher fuel consumption, which also contributes to increased CO2 emissions. The increase in hydrocarbon (HC) concentration by 3.7% can be attributed to the reduced combustion efficiency of E10 fuel under lean mixture operation. Although ethanol improves combustion efficiency in certain operating ranges, under conditions of excess air, some fuel may not fully combust, leading to higher emissions of unburned hydrocarbons. Despite the general tendency for NOx emissions to increase with lean mixtures, the observed reduction in NOx concentration in this case (by 4.4%) can be explained by several factors. Ethanol in E10 fuel contains oxygen, leading to a more uniform flame propagation in the combustion chamber. This can reduce localized high-temperature zones, where nitrogen oxides (NOx) are typically formed, thereby lowering NOx production compared to E5 fuel under the same lean mixture conditions. E10 also has a lower energy density compared to pure gasoline (E5). This means less energy is released per unit of fuel mass, which can result in slightly lower peak combustion temperatures, even in lean mixture conditions. For λ = 1.02 with E10, the combustion process may be slower or more extended over time compared to E5 fuel. This contributes to a reduction in peak temperatures in the combustion chamber, which in turn reduces NOx formation. Additionally, ethanol contains fewer impurities, such as nitrogen compounds, compared to pure gasoline. This further contributes to the overall reduction in NOx emissions when using E10 fuel. The analyzed case may concern a large group of vehicles and machines used in Poland manufactured before 2024.
The comparison of E5 and E10 fuels, with proper lambda (λ) coefficient regulation applied exclusively for E10 fuel, is presented in Figure 7. Engine control settings optimized for E10 fuel, when used with E5 fuel, resulted in lean mixture operation, corresponding to λ = 1.05 for E5. This adjustment led to an increase in CO concentration by 3%, HC by 19%, and NOx by 4%, while CO2 concentration remained constant. These changes in concentrations can be explained by the specific combustion process of very lean mixtures combined with the differences in the composition and properties of these fuels. Although E5 contains ethanol, which introduces additional oxygen into the fuel mixture, very lean mixtures (λ = 1.05) cause combustion to become less efficient. The excess air in very lean conditions promotes cooling in certain zones of the combustion chamber, potentially leading to incomplete oxidation of carbon molecules and an increase in CO concentrations. This is the effect of the so-called “diluted flame”, where the available oxygen does not always effectively react with the fuel under specific conditions. The ethanol in E5 supports more homogeneous combustion compared to non-oxygenated fuels, but in very lean mixtures, part of the fuel may still remain unburned. The excess oxygen in the λ = 1.05 mixture increases the likelihood of incomplete combustion of hydrocarbons in cooler regions of the combustion chamber, resulting in a significant increase in HC emissions. The positive effect of ethanol on combustion improvement is limited in very lean mixture conditions, as the combustion process becomes less stable. Lean mixtures (λ > 1.0) are characterized by higher combustion temperatures due to excess oxygen, which intensifies the chemical reactions leading to NOx formation. In the case of E5, the presence of ethanol and the oxygen it contains can promote more homogeneous combustion. However, with very lean mixtures, the increase in combustion-chamber temperatures becomes dominant, leading to higher NOx emissions. This is the case where new vehicles adapted to E10 fuel will be refueled with older-generation fuel, e.g., in countries that have not yet introduced E10 fuel.
Deng et al. in 2019 [51] demonstrated that changes in the λ coefficient result in consistent patterns of CO and NOx concentration changes, regardless of engine speed and load. The findings of their study align with those presented in this publication, namely that lean mixtures lead to an increase in NOx and a reduction in CO, while rich mixtures result in an increase in CO and a reduction in NOx.

4. Recommendations for Improvement

Improving the regulation of the AFR when transitioning from gasoline 95 or E5 to E10 requires adjusting the ECU to account for differences in stoichiometric AFR and ethanol content. E10 fuel has a lower stoichiometric AFR (~13.82:1) compared to gasoline 95 (14.7:1) and E5 (~14.25:1), necessitating an increased fuel dose to maintain λ=1. This can be addressed through several approaches: updating fuel maps in the ECU to modify injection timing values to provide additional fuel, ensuring adaptive control strategies are active so modern ECUs can adjust parameters in real time based on sensor inputs, and performing a reset or calibration if necessary. Implementing fuel composition-recognition systems, such as advanced sensors to directly measure ethanol content, allows the ECU to automatically adjust injection and ignition parameters. In cases where such sensors are unavailable, the ECU can be preprogrammed with fixed AFR values for specific fuels like E10. Ignition-timing adjustments can optimize combustion efficiency due to ethanol’s higher octane rating, with advanced ECU tuning enabling better utilization of E10’s properties. For older vehicles with carburetors or mechanical injection systems, manual adjustment of fuel delivery settings may be required. After implementing changes, diagnostic testing should confirm that λ remains close to 1 under E10 operation. Continuous monitoring of engine performance and emissions will validate the effectiveness of these modifications and ensure optimal fuel utilization and compliance with emission standards.

5. Discussion

Research on the performance differences of spark-ignition (SI) engines using gasoline 95, E5, and E10 does not always clarify whether the fuel-change process included adjustments to the AFR (air–fuel ratio) in the fuel injection control algorithm. In commercial engine control systems, altering the AFR is neither simple nor straightforward, as it requires new calibration parameters across all operating conditions. It appears that when authors do not mention changes to the AFR in their studies, they may assume the AFR for the fuel available at the time of vehicle production. Such studies may lead to incorrect conclusions regarding the use of E10 fuel if the engine control process is flawed (e.g., improper AFR adjustment). However, they do provide insight into the real-world response of older engine designs (calibrated for gasoline 95 or E5) to the introduction of E10 fuel on the market.
Altun et al. (2013) [52] conducted research on emissions using gasoline 95, E5, and E10 without specifying whether the AFR was adjusted during testing. Their results showed that E10 produced a CO concentration in the exhaust gases similar to E5 but lower than gasoline 95. Conversely, CO2 emissions were lowest for gasoline 95, while HC emissions were lowest for E10, followed by E5, and highest for gasoline 95. These findings suggest that the addition of ethanol to gasoline leads to more complete combustion, resulting in reduced CO and HC emissions but increased CO2 emissions. The results of these studies are consistent with the results of the authors of the article presented in Figure 5. The study does not provide specific information on whether the air–fuel ratio (AFR) was adjusted during testing to account for the different ethanol blends. Therefore, it cannot be conclusively determined from this study whether the elevated CO and HC emissions and reduced CO2 for gasoline 95 are due to AFR regulation for E10.
In laboratory tests, newer-generation engines programmed for E10 combustion may be tested using gasoline 95, which can significantly affect emission values and result interpretation. When the AFR is correctly regulated for gasoline 95, E5, and E10 (14.7:1 for gasoline 95, 14.1:1 for E5, and 13.8:1 for E10), maintaining λ = 1, emissions of CO, CO2, HC, and NOx vary depending on the chemical composition of the fuel. Fuels with bioethanol (E5 and E10) contain oxygen in their structure, promoting more complete combustion. Consequently, carbon monoxide (CO) emissions, which are a byproduct of incomplete combustion, are lower for E5 and E10 than for gasoline 95, with E10 emitting the least CO. On the other hand, carbon dioxide (CO2) emissions follow the opposite trend, with E10 emitting the most CO2, followed by E5 and gasoline 95. This is due to the more efficient combustion of bioethanol-containing fuels facilitated by the added oxygen, along with the lower energy content of bioethanol, which results in higher fuel consumption and further increases CO2 emissions. Similarly, hydrocarbons (HCs) are emitted in lower quantities by fuels containing bioethanol, as ethanol enhances combustion efficiency. Gasoline 95, which is composed entirely of hydrocarbons, emits the most HC, while E10 emits the least. However, nitrogen oxides (NOx) emissions are highest for E10, followed by E5 and gasoline 95. The increased NOx emissions result from the higher combustion temperatures associated with the more efficient burning of bioethanol-containing fuels, with E10 producing the most NOx due to its higher bioethanol content, while gasoline 95 generates the least.
Studies by Çakmak et al. (2023) [53] confirm that fuels with bioethanol (E5 and E10) reduce CO and HC emissions, making them more environmentally friendly in this regard. However, E10 emits more CO2 and NOx due to more efficient and higher-temperature combustion. The results of these studies are again consistent with the results presented in Figure 5. Gasoline 95, while emitting less NOx and CO2, has higher CO and HC emissions, which negatively affect air quality. Each fuel has its specific advantages and disadvantages, but E10 is generally more beneficial in reducing local pollutants, provided effective NOx control systems are in place.
Wu et al. (2004) [54] studied the effects of air–fuel ratios on engine performance and emissions in SI engines using ethanol–gasoline blends. They found that CO and HC emissions were reduced as ethanol content increased, due to the oxygen enrichment in the fuel. The smallest amounts of CO and HC and the largest CO2 emissions occurred near a slightly lean mixture (λ > 1). Their findings highlight that in lean combustion conditions, CO2 emissions are primarily controlled by the air–fuel equivalence ratio, whereas in rich combustion conditions, CO2 emissions are offset by CO emissions. The study also concluded that CO2 emissions per unit of power output for ethanol blends were similar to or lower than those of gasoline. Based on experimental data, the optimal ethanol content in gasoline and air–fuel equivalence ratio for engine performance and air pollution control was determined to be E10 with λ > 1 (slightly lean). Under these conditions, CO and HC emissions were reduced, while maintaining torque levels comparable to conventional fuels. However, excessively lean mixtures may increase NOx emissions and pose durability issues for the engine, underscoring the importance of precise AFR tuning and ethanol-content optimization to achieve the best balance between performance and emissions.
Further plans and tests are being conducted regarding E15 [55,56] fuel to investigate the impact of higher bioethanol content on engine performance and exhaust emissions. Such fuel is expected to cause additional disruptions in air–fuel mixture control. When a vehicle calibrated for AFR values corresponding to gasoline 95, E5, or E10 is fueled with E15, the actual lambda (λactual) can be determined by comparing the achieved AFR to the stoichiometric AFR of E15. The stoichiometric AFR values for each fuel are as follows: gasoline 95 at 14.7, E5 at approximately 14.1, E10 at approximately 13.8, and E15 at approximately 13.6. For a vehicle calibrated for gasoline 95, the actual lambda is calculated as λactual ≈ 1.081, indicating a lean mixture. If the vehicle is calibrated for E5, the actual lambda becomes λactual≈ 1.037, which is also a lean mixture but less severe. For a vehicle calibrated for E10, the actual lambda is λactual ≈ 1.015, representing a slightly lean mixture. In all cases, using E15 in a vehicle calibrated for another fuel results in a lean mixture (λ > 1), with the greatest deviation occurring when the vehicle is calibrated for gasoline 95 and the smallest deviation when calibrated for E10. These findings highlight the need for adjustments to the ECU or fuel injection system to correct the air–fuel ratio and maintain λ = 1, ensuring optimal combustion and minimizing the risk of increased emissions or engine performance issues. The actual lambda (λactual ≈ 1.081) for engines calibrated for gasoline 95 when fueled with E15 is close to the threshold for lean mixtures for gasoline 95 (λ = 1.1).

6. Conclusions

Addressing the challenges of properly using E10 fuel requires raising awareness among vehicle owners about the potential risks associated with this fuel and providing clear guidance on determining whether their vehicles are compatible. The use of E10 in vehicles not calibrated for the proper AFR regulation can lead to a leaner air–fuel mixture, causing the engine, when set to operate at λ = 1 for gasoline 95, to function near the upper limit of lean mixture adjustment for gasoline 95 (λ = 1.1), achieving an actual λ value of approximately λ = 1.065. To improve AFR regulation when transitioning to E10, it is necessary to update fuel maps in the ECU, recalibrate lambda sensors, and optimize ignition and fuel-injection settings. For older vehicles, manual adjustments to injection systems or carburetors may be required. The introduction of fuel composition sensors and wideband lambda sensors can further enhance regulation precision. Regular diagnostic tests are crucial to ensure proper engine operation and compliance with emission standards. Otherwise, increased NOx and CO emissions and accelerated wear of the engine and exhaust after-treatment system can be expected. Additionally, governments and fuel providers could implement programs to support retrofitting older vehicles or provide access to alternative fuels, such as E5 or pure gasoline, for vehicles that cannot safely use E10. Non-road small engines may require similar attention, including clear labeling and usage instructions to minimize risks associated with improper fuel use. While the transition to E10 is an essential step toward meeting EU renewable energy and emissions targets, it poses significant challenges for millions of vehicles and small engines not designed for higher-ethanol-content fuels. A comprehensive approach, including technical solutions, consumer education, and alternative fuel availability, is critical to ensure a smooth transition without compromising vehicle performance or durability.

Author Contributions

Conceptualization, Ł.W.; methodology, Ł.W., B.W., and Ł.G.; software, Ł.W., B.W. and Ł.G.; validation, Ł.W., B.W. and Ł.G.; formal analysis, Ł.W.; investigation, Ł.W., B.W. and Ł.G.; resources, Ł.W., B.W., Ł.G. and B.K.; data curation, Ł.W., B.W., Ł.G. and B.K.; writing—original draft preparation, Ł.W.; writing—review and editing, Ł.W.; visualization, Ł.W.; supervision, Ł.W.; project administration, Ł.W.; funding acquisition, Ł.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Umerenkova, K.; Borysenko, V.; Kondratenko, O.; Lievtierov, A. Determination of Thermophysical Properties of Alternative Motor Fuels as an Environmental Aspect of Internal Combustion Engines. Eng. Innov. 2023, 7, 51–59. [Google Scholar] [CrossRef]
  2. Warguła, Ł.; Kukla, M.; Krawiec, P.; Wieczorek, B. Reduction in Operating Costs and Environmental Impact Consisting in the Modernization of the Low-Power Cylindrical Wood Chipper Power Unit by Using Alternative Fuel. Energies 2020, 13, 2995. [Google Scholar] [CrossRef]
  3. Bembenek, M.; Melnyk, V.; Karwat, B.; Rokita, T.; Hnyp, M.; Mosora, Y.; Warguła, Ł. Study of the Technical and Operational Parameters of Injectors Using Biogas Fuel. Energies 2024, 17, 5445. [Google Scholar] [CrossRef]
  4. Kim, S.; Dale, B. Ethanol Fuels: E10 or E85—Life Cycle Perspectives (5 pp). Int. J. Life Cycle Assess. 2006, 11, 117–121. [Google Scholar] [CrossRef]
  5. González-García, S.; Gasol, C.M.; Gabarrell, X.; Rieradevall, J.; Moreira, M.T.; Feijoo, G. Environmental Aspects of Ethanol-Based Fuels from Brassica carinata: A Case Study of Second Generation Ethanol. Renew. Sustain. Energy Rev. 2009, 13, 2613–2620. [Google Scholar] [CrossRef]
  6. Holechek, J.L.; Geli, H.M.E.; Sawalhah, M.N.; Valdez, R. A Global Assessment: Can Renewable Energy Replace Fossil Fuels by 2050? Sustainability 2022, 14, 4792. [Google Scholar] [CrossRef]
  7. Silveira, S.; Khatiwada, D. Ethanol Production and Fuel Substitution in Nepal—Opportunity to Promote Sustainable Development and Climate Change Mitigation. Renew. Sustain. Energy Rev. 2010, 14, 1644–1652. [Google Scholar] [CrossRef]
  8. Raboni, M.; Viotti, P.; Capodaglio, A.G. A Comprehensive Analysis of the Current and Future Role of Biofuels for Transport in the European Union (EU). Rev. Ambiente Água 2015, 10, 9–21. [Google Scholar] [CrossRef]
  9. Sathish Kumar, T.; Ashok, B.; Saravanan, B.; Tamilvanan, A.; Szpica, D. Development of Optimal Engine Control Map for Flex Fuel Application in Ethanol Powered Direct Injection Spark Ignition Engine. Fuel 2025, 384, 133934. [Google Scholar] [CrossRef]
  10. Tosun, J. The Behaviour of Suppliers and Consumers in Mandated Markets: The Introduction of the Ethanol–Petrol Blend E10 in Germany. J. Environ. Policy Plan. 2018, 20, 1–15. [Google Scholar] [CrossRef]
  11. Khan, A.M.; Askari, G.H.; Ahmed, Z. The Performance and Cost Analysis on Bio Fuel Blends for Internal Combustion Engine. MATEC Web Conf. 2023, 381, 01012. [Google Scholar] [CrossRef]
  12. Dhande, D.Y.; Sinaga, N.; Dahe, K.B. Study on Combustion, Performance and Exhaust Emissions of Bioethanol-Gasoline Blended Spark Ignition Engine. Heliyon 2021, 7, e06380. [Google Scholar] [CrossRef] [PubMed]
  13. Rimkus, A.; Mejeras, G.; Matijošius, J. The Influence of Hydrogen and Oxygen (HHO) Gas on Engine Characteristics under the Effect of the Lean Mixtures of Gasoline and Bioethanol. Int. J. Hydrogen Energy 2023, 48, 39612–39624. [Google Scholar] [CrossRef]
  14. Lotko, W.; Smigins, R.; Tziourtzioumis, D.; Górska, M. Environmental Aspects of a Common Rail Diesel Engine Fuelled with Biodiesel/Diesel Blends. Adv. Sci. Technol. Res. J. 2022, 16, 192–201. [Google Scholar] [CrossRef]
  15. Siadkowska, K.; Barański, G.; Sochaczewski, R.; Wendeker, M. Experimental Investigation on Indicated Pressure and Heat Release for Direct Hydrogen Injection in a Dual Fuel Diesel Engine. Adv. Sci. Technol. Res. J. 2022, 16, 54–66. [Google Scholar] [CrossRef]
  16. Matzen, M.; Demirel, Y. Methanol and Dimethyl Ether from Renewable Hydrogen and Carbon Dioxide: Alternative Fuels Production and Life-Cycle Assessment. J. Clean. Prod. 2016, 139, 1068–1077. [Google Scholar] [CrossRef]
  17. von Blottnitz, H.; Curran, M.A. A Review of Assessments Conducted on Bio-Ethanol as a Transportation Fuel from a Net Energy, Greenhouse Gas, and Environmental Life Cycle Perspective. J. Clean. Prod. 2007, 15, 607–619. [Google Scholar] [CrossRef]
  18. Rokicki, T.; Bórawski, P.; Szeberényi, A. The Impact of the 2020–2022 Crises on EU Countries’ Independence from Energy Imports, Particularly from Russia. Energies 2023, 16, 6629. [Google Scholar] [CrossRef]
  19. Yan, L. Analysis of the International Oil Price Fluctuations and Its Influencing Factors. Am. J. Ind. Bus. Manag. 2012, 2, 39–46. [Google Scholar] [CrossRef]
  20. Su, G.; Ong, H.C.; Mofijur, M.; Mahlia, T.M.I.; Ok, Y.S. Pyrolysis of Waste Oils for the Production of Biofuels: A Critical Review. J. Hazard. Mater. 2022, 424, 127396. [Google Scholar] [CrossRef] [PubMed]
  21. Kumar, A.; Purohit, P.; Rana, S.; Kandpal, T.C. An Approach to the Estimation of the Value of Agricultural Residues Used as Biofuels. Biomass Bioenergy 2002, 22, 195–203. [Google Scholar] [CrossRef]
  22. Paul, S.; Mazumder, C.; Mukherjee, S. Challenges Faced in Commercialization of Biofuel from Biomass Energy Resources. Biocatal. Agric. Biotechnol. 2024, 60, 103312. [Google Scholar] [CrossRef]
  23. Valeika, G.; Matijošius, J.; Orynycz, O.; Rimkus, A.; Kilikevičius, A.; Tucki, K. Compression Ignition Internal Combustion Engine’s Energy Parameter Research Using Variable (HVO) Biodiesel and Biobutanol Fuel Blends. Energies 2024, 17, 262. [Google Scholar] [CrossRef]
  24. Ovaere, M.; Proost, S. Cost-Effective Reduction of Fossil Energy Use in the European Transport Sector: An Assessment of the Fit for 55 Package. Energy Policy 2022, 168, 113085. [Google Scholar] [CrossRef]
  25. Arabadjieva, K.; Bogojević, S. The European Green Deal: Climate Action, Social Impacts and Just Transition Safeguards. Yearb. Eur. Law 2024, yeae004. [Google Scholar] [CrossRef]
  26. Azhaganathan, G.; Bragadeshwaran, A. Critical Review on Recent Progress of Ethanol Fuelled Flex-Fuel Engine Characteristics. Int. J. Energy Res. 2022, 46, 5646–5677. [Google Scholar] [CrossRef]
  27. Green, Y. The Application of Ethanol Fuel: Taking the United States as An Example. Biol. Evid. 2024, 14, 1–10. [Google Scholar] [CrossRef]
  28. Hossain, N.; Mahlia, T.M.I.; Miskat, M.I.; Chowdhury, T.; Barua, P.; Chowdhury, H.; Nizamuddin, S.; Ahmad, N.B.; Zaharin, N.A.B.; Mazari, S.A.; et al. Bioethanol Production from Forest Residues and Life Cycle Cost Analysis of Bioethanol-Gasoline Blend on Transportation Sector. J. Environ. Chem. Eng. 2021, 9, 105542. [Google Scholar] [CrossRef]
  29. Yadav, V.; Sherly, M.A.; Ranjan, P.; Tinoco, R.O.; Boldrin, A.; Damgaard, A.; Laurent, A. Framework for Quantifying Environmental Losses of Plastics from Landfills. Resour. Conserv. Recycl. 2020, 161, 104914. [Google Scholar] [CrossRef]
  30. Warguła, Ł.; Lijewski, P.; Kukla, M. Influence of Non-Commercial Fuel Supply Systems on Small Engine SI Exhaust Emissions in Relation to European Approval Regulations. Environ. Sci. Pollut. Res. 2022, 29, 55928–55943. [Google Scholar] [CrossRef] [PubMed]
  31. Al-Arkawazi, S.A.F. Analyzing and Predicting the Relation between Air–Fuel Ratio (AFR), Lambda (λ) and the Exhaust Emissions Percentages and Values of Gasoline-Fueled Vehicles Using Versatile and Portable Emissions Measurement System Tool. SN Appl. Sci. 2019, 1, 1370. [Google Scholar] [CrossRef]
  32. Warguła, Ł.; Lijewski, P.; Kukla, M. Effects of Changing Drive Control Method of Idling Wood Size Reduction Machines on Fuel Consumption and Exhaust Emissions. Croat. J. For. Eng. 2023, 44, 137–151. [Google Scholar] [CrossRef]
  33. Waluś, K.J.; Warguła, Ł.; Krawiec, P.; Adamiec, J.M. The Impact of the Modernization of the Injection-Ignition System on the Parameters of Motion of the Motorcycle. Procedia Eng. 2017, 177, 393–398. [Google Scholar] [CrossRef]
  34. Caban, J.; Seńko, J.; Słowik, T.; Dowkontt, S.; Górnicka, D. Analysis of the Influence of Fuel Dose on the Electrical Parameters of the Starting Process of a Single-Cylinder Diesel Engine. Adv. Sci. Technol. Res. J. 2024, 18, 55–65. [Google Scholar] [CrossRef]
  35. Eickenhorst, R.; Koch, T. An Experimental Study on Aging Effects of the Air–Fuel Ratio Swing on Modern Gasoline Three-Way Catalysts. Automot. Engine Technol. 2023, 8, 177–192. [Google Scholar] [CrossRef]
  36. Herner, H.; Riehl, H.-J. Electrical Engineering and Electronics in Motor Vehicles (Elektrotechnika i Elektronika w Pojazdach Samochodowych); WKŁ: Warszawa, Poland, 2013; ISBN 978-83-206-1921-8. (In Polish) [Google Scholar]
  37. Tucki, K.; Orynycz, O.A.; Mruk, R.; Kulesza, E.; Ruchała, P.; Wąsowicz, G. Analytical, Computer and Laboratory Modelling of the Effect of the Fuel Used in the Spark Ignition Engine of the Selected Vehicle on the Operating Parameters and Exhaust Gas Composition. Adv. Sci. Technol. Res. J. 2024, 18, 96–112. [Google Scholar] [CrossRef]
  38. Bradley, D. Chapter 2—Fundamentals of Lean Combustion. In Lean Combustion; Dunn-Rankin, D., Ed.; Academic Press: Burlington, MA, USA, 2008; pp. 19–54. ISBN 978-0-12-370619-5. [Google Scholar]
  39. Khrulev, A.E.; Saraiev, O.V. The Method of Expert Assessment of the Technical Condition of an Automobile Engine after Overheating. Автомобільний Транспорт 2021, 48, 5–16. [Google Scholar] [CrossRef]
  40. Fuć, P.; Sokolnicka-Popis, B.; Ziółkowski, A.; Bednarek, M.; Jagielski, A.; Michałowska, A. Technology for Manufacturing Catalytic Systems Using a Pilot Line for Precious Metal Recovery. Combust. Engines 2023, 193, 89–96. [Google Scholar] [CrossRef]
  41. Porsin, A.V.; Bubnov, K.V.; Moskalets, Y.A.; Nadareishvili, G.G.; Terenchenko, A.S.; Alikin, E.A.; Ushenin, A.V. A Destruction Mechanism of a Three-Way Catalyst Due to a Failure of Fuel Supply in a Spark Ignition Engine. Emiss. Control Sci. Technol. 2021, 7, 163–173. [Google Scholar] [CrossRef]
  42. Yamin, J.A.; Sheet, E.A.E.; Rida, K.S. Relative Change in SI Engine Performance Using Hydrogen and Alcohol as Fuel Supplements to Gasoline. Adv. Sci. Technol. Res. J. 2021, 15, 144–155. [Google Scholar] [CrossRef]
  43. Ijaz Malik, M.A.; Usman, M.; Akhtar, M.; Farooq, M.; Saleem Iqbal, H.M.; Irshad, M.; Shah, M.H. Response Surface Methodology Application on Lubricant Oil Degradation, Performance, and Emissions in SI Engine: A Novel Optimization of Alcoholic Fuel Blends. Sci. Prog. 2023, 106, 1–42. [Google Scholar] [CrossRef]
  44. Kalghatgi, G.T. Developments in Internal Combustion Engines and Implications for Combustion Science and Future Transport Fuels. Proc. Combust. Inst. 2015, 35, 101–115. [Google Scholar] [CrossRef]
  45. Saha, A.; Ojanperä, A.-M.; Hyvonen, J.; Aengeby, J.; Tidholm, J.; Andersson, O.; Tunestal, P. The Influence of Ignition Control Parameters on Combustion Stability and Spark Plug Wear in a Large Bore Gas Engine; SAE International: Warrendale, PA, USA, 2023. [Google Scholar]
  46. Dziubak, T.; Karczewski, M. Operational Malfunctions of Turbochargers—Reasons and Consequences. Combust. Engines 2016, 164, 13–21. [Google Scholar] [CrossRef]
  47. Pokluda, J.; Kianicová, M. Assessment of Performance Capability of Turbine Blades with Protective Coatings after Overheating Events. Eng. Fail. Anal. 2010, 17, 1389–1396. [Google Scholar] [CrossRef]
  48. Warguła, Ł.; Waluś, K.J.; Wieczorek, B.; Zakaria, R. The Impact of the Modernization of the Ignition and Injection System in the Dniepr MT 11 Motorcycle on the Frequency of Service Operations. Mater. Mech. Eng. Technol. 2023, 2023, 15–22. [Google Scholar] [CrossRef] [PubMed]
  49. Yoo, Y.H.; Park, I.J.; Kim, J.G.; Kwak, D.H.; Ji, W.S. Corrosion Characteristics of Aluminum Alloy in Bio-Ethanol Blended Gasoline Fuel: Part 1. The Corrosion Properties of Aluminum Alloy in High Temperature Fuels. Fuel 2011, 90, 1208–1214. [Google Scholar] [CrossRef]
  50. Davis, G.; Hoff, C. The Effect of Using Ethanol-Blended Gasoline on the Performance and Durability of Fuel Delivery Systems in Classic Automobiles; SAE International: Warrendale, PA, USA, 2010. [Google Scholar]
  51. Deng, B.; Li, Q.; Chen, Y.; Li, M.; Liu, A.; Ran, J.; Xu, Y.; Liu, X.; Fu, J.; Feng, R. The Effect of Air/Fuel Ratio on the CO and NOx Emissions for a Twin-Spark Motorcycle Gasoline Engine under Wide Range of Operating Conditions. Energy 2019, 169, 1202–1213. [Google Scholar] [CrossRef]
  52. Altun, S.; Oztop, H.F.; Oner, C.; Varol, Y. Exhaust Emissions of Methanol and Ethanol-Unleaded Gasoline Blends in a Spark Ignition Engine. Therm. Sci. 2013, 17, 291–297. [Google Scholar] [CrossRef]
  53. Çakmak, A.; Kapusuz, M.; Özcan, H. Experimental Research on Ethyl Acetate as Novel Oxygenated Fuel in the Spark-Ignition (SI) Engine. Energy Sources Part A Recovery Util. Environ. Eff. 2023, 45, 178–193. [Google Scholar] [CrossRef]
  54. Wu, C.-W.; Chen, R.-H.; Pu, J.-Y.; Lin, T.-H. The Influence of Air–Fuel Ratio on Engine Performance and Pollutant Emission of an SI Engine Using Ethanol–Gasoline-Blended Fuels. Atmos. Environ. 2004, 38, 7093–7100. [Google Scholar] [CrossRef]
  55. Sharma, N.; Agarwal, A.K. Effect of the Fuel Injection Pressure on Particulate Emissions from a Gasohol (E15 and M15)-Fueled Gasoline Direct Injection Engine. Energy Fuels 2017, 31, 4155–4164. [Google Scholar] [CrossRef]
  56. Masum, B.M.; Masjuki, H.H.; Kalam, M.A.; Palash, S.M.; Habibullah, M. Effect of Alcohol–Gasoline Blends Optimization on Fuel Properties, Performance and Emissions of a SI Engine. J. Clean. Prod. 2015, 86, 230–237. [Google Scholar] [CrossRef]
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Figure 1. Exhaust emissions depending on the air–fuel mixture composition (own analysis, based on [36]), where A—with flue-gas treatment system (three-functional catalytic system); and B—without flue-gas treatment system.
Figure 1. Exhaust emissions depending on the air–fuel mixture composition (own analysis, based on [36]), where A—with flue-gas treatment system (three-functional catalytic system); and B—without flue-gas treatment system.
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Figure 2. Exhaust emissions depending on the air–fuel mixture composition, own analysis based on [36], where A—with flue-gas treatment system (three-functional catalytic system), B—without flue-gas treatment system; own analysis based on; (a) the lambda coefficient (λ = 1) and the control range field, (b) the lambda coefficient (λ = 1.022) and the control range field, (c) the lambda coefficient (λ = 1.065) and the control range field, (d) the lambda coefficient (λ = 1.045) and the control range field.
Figure 2. Exhaust emissions depending on the air–fuel mixture composition, own analysis based on [36], where A—with flue-gas treatment system (three-functional catalytic system), B—without flue-gas treatment system; own analysis based on; (a) the lambda coefficient (λ = 1) and the control range field, (b) the lambda coefficient (λ = 1.022) and the control range field, (c) the lambda coefficient (λ = 1.065) and the control range field, (d) the lambda coefficient (λ = 1.045) and the control range field.
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Figure 3. Lambda (λ) correction values to achieve λ = 1 depending on the type of fuel and the fuel type programmed in the ECU; own analysis based on [36], where A—with flue-gas treatment system (three-way catalytic system); and B—without flue-gas treatment system. Own analysis based on (a) the lambda coefficient (λ = 1) and the control range field, (b) the lambda coefficient (λ = 0.98) and the control range field, (c) the lambda coefficient (λ = 0.94) and the control range field, and (d) the lambda coefficient (λ = 0.96) and the control range field.
Figure 3. Lambda (λ) correction values to achieve λ = 1 depending on the type of fuel and the fuel type programmed in the ECU; own analysis based on [36], where A—with flue-gas treatment system (three-way catalytic system); and B—without flue-gas treatment system. Own analysis based on (a) the lambda coefficient (λ = 1) and the control range field, (b) the lambda coefficient (λ = 0.98) and the control range field, (c) the lambda coefficient (λ = 0.94) and the control range field, and (d) the lambda coefficient (λ = 0.96) and the control range field.
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Figure 4. Schematic diagram of the conducted tests, where A and B are the adjustment value and fuel type during selected measurement variants, and the numbers (1, 2, and 3) are the order of the conducted test variants.
Figure 4. Schematic diagram of the conducted tests, where A and B are the adjustment value and fuel type during selected measurement variants, and the numbers (1, 2, and 3) are the order of the conducted test variants.
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Figure 5. Comparison of E5 and E10 fuel with λ regulation equal to 1, corresponding to the proper AFR for E5 fuel (14.25:1) and E10 fuel (13.82:1).
Figure 5. Comparison of E5 and E10 fuel with λ regulation equal to 1, corresponding to the proper AFR for E5 fuel (14.25:1) and E10 fuel (13.82:1).
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Figure 6. Comparison of E5 and E10 fuel with a value equal to 1 for E5 fuel (AFR 14.25:1). For E10 fuel, the regulation value is incorrect because it is retained for E5.
Figure 6. Comparison of E5 and E10 fuel with a value equal to 1 for E5 fuel (AFR 14.25:1). For E10 fuel, the regulation value is incorrect because it is retained for E5.
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Figure 7. Comparison of E5 and E10 fuel with a value equal to 1 for E10 fuel (AFR 13.82:1). For E5 fuel, the regulation value is incorrect because it is retained for E10.
Figure 7. Comparison of E5 and E10 fuel with a value equal to 1 for E10 fuel (AFR 13.82:1). For E5 fuel, the regulation value is incorrect because it is retained for E10.
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Table 1. Technical specification of the German GX390 engine.
Table 1. Technical specification of the German GX390 engine.
PropertiesCharacteristics
Swept volume389 cm3
Engine maximal power at 3600 rpm9.56 kW/13 HP
Engine maximal torque at 2500 rpm26.5 Nm
Bore/stroke88 mm/64 mm
Engine typeFour-stroke, OHV (overhead valve)
Number of cylinders1
IgnitionElectronic, without ignition timing adjustment
Table 2. Fuel characteristics of E5 and E10. MON = Motor Octane Number; RON = Research Octane Number.
Table 2. Fuel characteristics of E5 and E10. MON = Motor Octane Number; RON = Research Octane Number.
PropertiesE5E10
Ethanol contentUp to 5%Up to 10%
Octane Number MON (RON)85 (95)85 (95)
Density under reference conditions (liquid phase) (kg/m3)745–760750–765
Calorific value (MJ/kg)42.742.0
Boiling temperature (°C)25–22525–225
Air–fuel ratio (AFR) for stoichiometric mixture (mass)14.25:113.82:1
Table 3. Technical data of the exhaust gas analyzer.
Table 3. Technical data of the exhaust gas analyzer.
Tested ComponentMeasuring RangeResolution
CO0–15%0.001%
CO20–20%0.1%
HC0–20.000 ppm1 ppm
O20–21.7%0.01% (O2 < 4%)
0.1% (O2 > 4%)
NOx0–5.000 ppm1 ppm
λ0.8–1.20.001
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Warguła, Ł.; Wieczorek, B.; Gierz, Ł.; Karwat, B. Critical Concerns Regarding the Transition from E5 to E10 Gasoline in the European Union, Particularly in Poland in 2024—A Theoretical and Experimental Analysis of the Problem of Controlling the Air–Fuel Mixture Composition (AFR) and the λ Coefficient. Energies 2025, 18, 852. https://doi.org/10.3390/en18040852

AMA Style

Warguła Ł, Wieczorek B, Gierz Ł, Karwat B. Critical Concerns Regarding the Transition from E5 to E10 Gasoline in the European Union, Particularly in Poland in 2024—A Theoretical and Experimental Analysis of the Problem of Controlling the Air–Fuel Mixture Composition (AFR) and the λ Coefficient. Energies. 2025; 18(4):852. https://doi.org/10.3390/en18040852

Chicago/Turabian Style

Warguła, Łukasz, Bartosz Wieczorek, Łukasz Gierz, and Bolesław Karwat. 2025. "Critical Concerns Regarding the Transition from E5 to E10 Gasoline in the European Union, Particularly in Poland in 2024—A Theoretical and Experimental Analysis of the Problem of Controlling the Air–Fuel Mixture Composition (AFR) and the λ Coefficient" Energies 18, no. 4: 852. https://doi.org/10.3390/en18040852

APA Style

Warguła, Ł., Wieczorek, B., Gierz, Ł., & Karwat, B. (2025). Critical Concerns Regarding the Transition from E5 to E10 Gasoline in the European Union, Particularly in Poland in 2024—A Theoretical and Experimental Analysis of the Problem of Controlling the Air–Fuel Mixture Composition (AFR) and the λ Coefficient. Energies, 18(4), 852. https://doi.org/10.3390/en18040852

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