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A gasoline engine with an electronically controlled fuel injection system has substantially better fuel economy and lower emissions than a carburetted engine. In general, the stability of engine operation is improved with fuel injector, but the stability of engine operation at idle is not improved compared with a carburetted gasoline engine. In addition, the increase in time that an engine is at idle due to traffic congestion has an effect on the engine stability and vehicle reliability. Therefore, in this research, we will study the influence of fuel injection timing, spark timing, dwell angle, and air-fuel ratio on engine stability at idle.

A new empirical formula for instantaneous heat transfer coefficients was determined. The determination of this formula is in necessary for prediction of the instantaneous value of heat transfer coefficients to analyze in more detail the time variation of heat transfer rate from the gas to the wall in the combustion chamber of a spark ignition engine. The following formula was determined. Using this empirical formula the instantaneous heat transfer coefficients of gas in the combustion chamber of spark ignition engine was predicted and compared with experimental values.

A gasoline spark-ignition (SI) engine with an electronically controlled fuel injection system has substantially better fuel economy and lower emissions than a carburetted engine. In general, the stability of engine operation is improved with fuel injection, but the combustion stability at idle is not improved compared to a carburetted engine. The combustion variability in SI engines limits the use of lean mixtures, the amount of recycled exhaust the engine will tolerate, and lower idle speeds because of increased emissions and poor engine stability. In addition, the increase in time that an engine is at idle due to traffic congestion has an effect on the engine stability and vehicle reliability. Therefore, in this research, we will study the influence of ignition energy, fuel injection timing, spark timing, and air-fuel ratio on gasoline engine stability at idle.