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Influence of Failures not Detected by the On-Board Diagnostic System on the Performance and Pollutant Emissions of a Spark Ignition Engine

Abstract:

This research is aimed at determining the influence on the performance and concentration of exhaust gas emissions of a spark ignition (SI) engine by inducing controlled failures not detected by the on-board diagnostic system (OBD). Through the Analytic Hierarchy Process (AHP), two defects are selected to cause, obtaining the air filter in poor condition and excessive spark gap. The experimental unit is a Hyundai Accent vehicle that is subjected to 16 treatments on the dynamometric bench with the engine at full load and constant speed, both in normal and defective operating conditions; two commercial fuels from the region are used with a RON of 87 and 92, respectively, whose preference of the Ecuadorian population is conditioned by the worrying increase in fuel prices. The results obtained indicate that the highest fuel consumption is 11.75 L/100 km caused by the clogged air filter and lower octane naphtha. Power and torque behave similarly; their lowest values are 14.2 kW and 67.8 Nm, respectively, due to the clogged air filter combined with the faulty spark plug and 87 octane gasoline. The highest concentration of CO is 5.21%, due to the defective spark plug together with the clogged air filter, and the HC emissions amount to 179 ppm with the clogged air filter; both polluting gases using lower quality naphtha.