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An automotive powertrain control system using only one signal of the output shaft speed sensor has been investigated in order to lower the system costs and to simplify the calibration process A new smooth torque method after downshifting is described which is based on the differential value of automatic transmission output shaft speed The starting time of the engine torque control for restraining the torque fluctuation after downshifting can be detected accurately as a result of using the differential value The proposed engine torque control method is advantageous since it simplifies the calibration process for the data tables Moreover, it is possible to lower the cost of parts used in the automatic transmission control since speed and torque sensors are unnecessary The smooth torque control method was examined using a test vehicle and the same smooth torque after downshifting was obtained when the new method was employed

An automatic matching method for engine control parameters is described which can aid efficient development of new engine control systems. In a spark-ignition engine, fuel is fed to a cylinder in proportion to the air mass induced in the cylinder. Air flow meter characteristics and fuel injector characteristics govern fuel control. The control parameters in the electronic controller should be tuned to the physical characteristics of the air flow meter and the fuel injectors during driving. Conventional development of the engine control system requires a lot of experiments for control parameter matching. The new matching method utilizes the deviation of feedback coefficients for stoichiometric combustion. The feedback coefficient reflects errors in control parameters of the air flow meter and fuel injectors. The relationship between the feedback coefficients and control parameters has been derived to provide a way to tune control parameters to their physical characteristics.

A new air-fuel ratio control algorithm and its effect on automotive engine operation is described. The system consists of a wide range air-fuel ratio sensor and a single point injector with an ultrasonic fuel atomizer. The air-fuel ratio control adopts PID control and it has built-in learning control. A 16 bit microcomputer is used for the latter. The results of three studies are given. The first deals with adaptive PID gain control for various conditions. The second is the new learning control which uses an integration terra. The third is individual cylinder air-fuel ratio control.