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Flame propagation was detected with ionization probes located at a spark plug and a head gasket to study the relations of ionization signal to the flame propagation period. Five ionization probes were inserted at a spark plug to detect the initial flame development and eight ionization probes were inserted at a head gasket to detect the overall flame propagation. Experiments were done while the A/F ratio, load and engine speed were varied. In the fast acceleration period, lean peak phenomenon due to the fuel wall wetting occurred for one or two cycles. Ionization signals were used to determine the flame propagation duration during fast acceleration and the lean peak could be avoided by injecting proper amount of fuel.

This paper evaluates how the fuel consumption of the average new U.S. passenger car will be penalized if engine and vehicle improvements continue to be focused on developing bigger, heavier and more powerful automobiles. We quantify a parameter called the Emphasis on Reducing Fuel Consumption (ERFC) and find that there has been little focus on improving fuel consumption in the U.S. over the past twenty years. In contrast, Europe has seen significantly higher ERFC. By raising the ERFC over the next few decades, we can reduce the average U.S. new car's fuel consumption by up to some 40 percent and cut the light-duty vehicle fleet's fuel use by about a quarter. Achieving substantial fuel use reduction will remain a major challenge if automobile size, weight and power continue to dominate.

This study investigates the causes for tailpipe mixture strength excursions during transient operation of an electronically controlled, central fuel injected engine. The investigation was made using a Ford 5.0L V8 engine instrumented to enable continuous monitoring of the tailpipe air-fuel ratio. Transient excursions of up to 20% are observed under warm engine conditions. Two causes of the excursions were identified: system time delays and fuel droplet deposition on induction system surfaces. A programmable control strategy was developed to compensate for observed lean excursions during accelerations. This was done by modifying the injector signal to provide the necessary fuel enrichment. Transient requirements were optimized across a range of engine operations. The results have been summarized in two sets of curves-one defining the enrichment fuel volume and the other specifying the form of enrichment fuel supply.