AEEJ : Journal of Automotive Engineering and Vocational Education

Development and Content Validation of a Psychomotor Assessment Instrument for Conventional Distributor-Type Diesel Fuel System Maintenance

Sugeng Riyadi — 2026-06-30

Psychomotor assessment in vocational high schools often remains subjective and insufficiently standardized, particularly in practical automotive learning related to conventional distributor-type diesel fuel systems. This study developed a performance assessment instrument to evaluate students’ technical competence in vocational automotive education more objectively. A Research and Development design adapted from Sugiyono’s model was applied up to the expert validation stage. The instrument comprised three integrated components: a Job Sheet, Work Sheet, and Assessment Sheet, structured using hierarchical indicators of psychomotor assessment from Imitation (P1) to Naturalization (P5). Five experts, consisting of three content experts and two assessment-instrument experts, evaluated the instrument using a four-point Likert scale. The validation data were analyzed using Aiken’s V to examine content, construct, language, and usability validity. The results showed that all components obtained Aiken’s V values above 0.80, indicating valid expert judgment across the assessed aspects. The developed instrument provides an initial valid basis for more structured, transparent, and consistent assessment of diesel fuel system maintenance skills in vocational practice.

Bioethanol Production from Sugarcane Bagasse and Pineapple Peel Waste and Its Combustion Characteristics

Diswanto Diswanto — 2026-06-30

Growing demand for renewable fuels has increased interest in converting agricultural and fruit-processing residues into bioethanol. This study evaluated sugarcane bagasse and pineapple peel waste as feedstocks for bioethanol production and compared the combustion characteristics of the resulting fuels. Bioethanol was produced through pretreatment, hydrolysis, fermentation using yeast, and distillation. The samples were then examined based on boiling-point range, flame color, flame height, flame area, and flame duration at fuel volumes of 1, 2, and 3 mL. The pineapple peel bioethanol showed a boiling-point range closer to ethanol and produced flame-height values closer to pure ethanol, particularly with 8 g yeast, whereas Pertamax generated the highest flame height and flame area overall. These results indicate that sugarcane bagasse and pineapple peel waste are promising feedstocks for preliminary bioethanol production, with pineapple peel showing better combustion-related characteristics among the waste-derived samples.

Fuel Consumption and Air–Fuel Ratio of a Modified-Compression-Ratio Engine Using 8- and 10-Hole Injectors with E90–E100 Bioethanol Blends

M. Reza — 2026-06-30

High-bioethanol blends require appropriate fuel-injection control, particularly in engines with modified compression ratios. This study evaluated fuel consumption and air–fuel ratio (AFR) of a modified-compression-ratio spark-ignition engine using 8- and 10-hole injectors with E90, E95, and E100 blends. Experiments were conducted at engine speeds from 2000 to 8000 rpm. Fuel consumption was measured using a flow meter, while AFR was recorded during dynamometer testing. Fuel consumption increased with engine speed for both injector types. E90 produced the lowest average fuel consumption, at 1.102 L/hour for the 8-hole injector and 1.209 L/hour for the 10-hole injector. Across all fuel blends, the 8-hole injector showed lower average fuel consumption, whereas the 10-hole injector showed a narrower AFR range. These findings indicate that injector-hole configuration and high-bioethanol blend composition should be considered when tuning fuel delivery in modified-compression-ratio engines.

Android-Based Learning Media Designed with Figma for Mechanical Measuring Instruments in Vocational Automotive Education

Arga Farid Ahmadi — 2026-06-30

Repetitive and conventional learning can make mechanical measuring instrument topics difficult for vocational students to understand. This study developed and initially evaluated Android-based learning media designed with Figma for Mechanical Measuring Instruments. The research used the ADDIE development model with a pre-experimental one-group pretest–posttest design involving Grade X TKRO students. Product feasibility was assessed by media and material experts, while learning outcomes were examined through pretest, posttest, t-test, N-Gain, and student responses. The media expert score was 85.4%, and the material expert score was 90.8%, both in the very feasible category. The average score increased from 43.6 in the pretest to 80.2 in the posttest. The reported t-test value was 44.892 > 2.026, with an N-Gain of 0.67, indicating moderate improvement. Student responses reached 86.5%, categorized as very good.

Air–Fuel Ratio Evaluation in Open-Loop ECU Mapping for a KZR Engine: A Trade-Off Analysis of Power, Torque, and Fuel-Efficiency Potential

Muhammad Ilham Ramadhan — 2026-06-30

An open-loop ECU operates without oxygen-sensor feedback, making Air–Fuel Ratio (AFR) control dependent on the preset fuel map. This study evaluated how three AFR settings in open-loop ECU mapping relate to the performance characteristics of a Honda KZR engine. A dynamometer-based experiment was conducted on a Honda Vario 125 KZR engine using Pertalite RON 90 and AFR targets of 11.7, 13.1, and 14.1. The evaluated parameters were engine power, torque response, and fuel-efficiency potential inferred from AFR characteristics. The results showed that AFR 13.1 produced the highest reported power output of 11.0 HP, whereas AFR 14.1 indicated a more favourable fuel-efficiency potential. AFR 11.7 represented an over-rich setting with the least favourable efficiency tendency. These findings indicate a trade-off between performance-oriented and economy-oriented AFR settings in open-loop ECU mapping.

Feasibility Evaluation of a 110 cc-Class Automatic Motorcycle Engine Cutaway for Supporting Practical Curriculum Implementation in Automotive Vocational Education

Ichsan Nasution — 2026-07-03

Automatic motorcycle engines are closed mechanical assemblies that limit students’ observation of internal components during vocational practice. This study developed and evaluated the feasibility of a 110 cc-class automatic motorcycle engine cutaway for supporting practical curriculum implementation in automotive vocational education. A Research and Development design with the ADDIE model was used. The product exposed key components, including the piston, cylinder, combustion chamber, crankshaft, valve mechanism, lubrication passages, and automatic transmission section, as a real-object medium for observing automatic engine mechanisms. Feasibility data were obtained from two media experts, two material experts, and responses from 25 Automotive Engineering students after limited implementation. Five-point Likert-scale data were analyzed descriptively. Media expert validation reached 86%, and material expert validation reached 90%, both categorized as highly feasible. Student responses reached 90%, categorized as very good. The cutaway was feasible and accepted, although learning effectiveness was not measured.

Problem-Based Learning to Support Creative Thinking Skills in Automotive Engineering Students: A Classroom Action Research Study

ilham yuliady — 2026-06-30

Low creative thinking skills in automotive engineering learning can limit students’ ability to generate, adapt, and elaborate technical solutions. This study described the implementation of Problem-Based Learning (PBL) and examined changes in students’ creative thinking skills in the Fundamentals of Automotive Engineering course. A Classroom Action Research design was used with 21 Automotive Engineering students and conducted in two cycles consisting of planning, action, observation, and reflection. Data were collected using observation sheets on creative thinking indicators and analyzed descriptively based on creativity categories. In the pre-cycle condition, most students were classified as fairly creative (52.38%), while only 4.76% were very creative. After PBL implementation in Cycle II, the creative category increased to 47.62% and the very creative category increased to 28.57%, while the least creative category decreased to 0%. These findings suggest that PBL can support the development of students’ creative thinking in automotive engineering learning.

Implementation of Problem-Based Learning in CAD Instruction for Automotive Engineering Students : Classroom Action Research on Engagement and Learning Outcomes

Zulfadli Zulfadli — 2026-06-30

Low student engagement and modest Computer-Aided Design (CAD) learning outcomes remain challenges in automotive engineering education. This study examined the implementation of Problem-Based Learning (PBL) to support student engagement and CAD learning achievement in an Automotive Engineering course. A Classroom Action Research design was conducted in two cycles comprising planning, action, observation, and reflection. The participants were 25 Automotive Engineering students in the 2025/2026 even semester. Data were collected through observation, pre-test, post-test, and documentation, and analyzed descriptively. The results showed that learning mastery increased from 72% in Cycle I to 88% in Cycle II, while the average score increased from 70.04 to 78.48. Classroom observations also indicated more active participation in discussion, problem-solving, group work, and presentations. These findings suggest that PBL can support CAD learning achievement and student engagement in this classroom action context.

Experimental Evaluation of Exhaust Emission Characteristics and Fuel Consumption of an F8A Engine with HHO Electrolyzer Addition

Rafly Pratama — 2026-06-30

Growing vehicle use has increased interest in combustion additives that may reduce fuel use and exhaust emissions in conventional engines. This study evaluated an HHO-based electrolyzer system applied to a carburetted F8A engine without internal engine modification. An experimental comparison was conducted under standard operation without HHO and with an active electrolyzer at 800, 2000, 3000, and 4000 rpm. The measured parameters were CO, CO₂, HC, O₂, lambda, and fuel consumption. HHO addition reduced HC emissions by 14.2%, decreased O₂ by 18.5%, increased CO₂ by 10.9%, and shifted lambda from 1.197 to 1.124, indicating a movement toward more complete combustion. However, CO increased by 10.0%. Fuel consumption decreased by 7.0% at 800 rpm, 7.3% at 3000 rpm, and 9.8% at 4000 rpm, but increased by 4.5% at 2000 rpm. These findings indicate that HHO addition can modify the emission profile and fuel consumption of a carburetted F8A engine, although its benefits are engine-speed dependent.