A Study of Idle Speed Control Performance Benchmarking of 1,000 cc. - 1,500 cc. Engine

Abstract

The main objective of this study is to conduct a performance benchmarking of idle speed control system in small automotive engines between 1,000 to 1,500 cc in Thailand. The outcome will be used as a guideline to develop the idle speed control system of the Sample Engine. The performance benchmarking examined 3 different types of engine management system namely; D-Jetronic, L-Jetronic, and the D-Jetronic incorporate with L-Jetronic. The experiment was divided into 16 test conditions which affect the performance of the idle speed control system. Performance indicators were the average of engine speed (N), standard deviation of engine speed (), error value of engine speed from the target speed (), overshoot, undershoot and track time. The result indicated that Engine “J” with Djetronic engine management system was obtained the highest score and was used to improve the Sample Engine. There are 3 main findings to improve and further develop the Sample Engine. 1) Rapid response of the air intake compensation during the load changes has significant impact on the idle speed control performance. The responsiveness can be improved by, for example, designing the location of the air sensor to be closer to the engine. 2) To return to the target idle speed after high engine speed, instantaneous air intake compensation showed shorter track time than stepping air intake compensation. 3) Size of both battery and alternator has significant impact on the idle speed control performance. The result indicated that automobile sample with a smaller battery and a larger alternator has better performance. This is due to less voltage fluctuation during the idle speed since charging time from the alternator to the battery and the duration of power drawn from the engine to generate electricity was shorter. Thus, the key findings from the study could be used to improve and further develop the Sample Engine in the future.