An investigation of throttle response of engines during warm-up was conducted using various gasolines. Test data were obtained from an engine on a test bench at intermediate temperature around 20∼ 30 °C. By using the engine test bench data, correlation coefficients between engine response time and gasoline characteristics were calculated.
The result shows that the middle range of distillation temperature is an important factor in gasoline characteristics for warm-up driveability of fuel injected engines. It also shows that 50% distillation temperature can be used as one indication of warm-up driveability. This indication is effective only for hydrocarbon type gasolines. In the case of MTBE blended gasoline, the distillation temperature becomes low when MTBE is blended to gasoline, but throttle response was not improved.
It is also found that the effect of gasoline distillation on throttle response is enhanced by intake valve deposits. Hence effect of gasoline detergent additive in Japanese market was investigated. Some of the detergents produced more intake valve deposits than no detergent.
It is concluded that distillation characteristics and detergent additive are important factors of gasoline quality for engine response, in other words, vehicle driveability.