Abstract: Methods are presented to remove from misfire/roughness measures both acceleration effects and those errors which are of a cyclical nature over the engine firing cycle. Included in the latter category are errors which repeat every revolution, e.g. tooth spacing errors resulting from manufacturing tolerances on a multitoothed wheel used to measure speed. Also included are errors arising from the cylinder by cylinder variations occurring in one firing cycle which would be essentially the same in neighboring firing cycles, e.g. mechanical and electrical tolerance effects that are cylinder based. These methods permit the correction in each cylinder measure of such cyclic errors on a cycle basis, i.e., after the completion of one or more of the cycles causing the error, or on a cylinder by cylinder basis, i.e., after the completion of the interval associated with an individual cylinder.

Abstract: An elastic model of the engine-drivetrain system is proposed. Measured crankshaft speed fluctuation data is developed and computations are made from the model to determine the fluctuation waveform of both the total engine torque being developed and the engine pressure torque. Utilizing the engine pressure torque fluctuation waveform, the mean level of engine torque being developed is obtained, thus providing the full engine pressure torque waveform. Finally, the engine pressure torque waveform is used to obtain the cylinder pressure waveform which gave rise to it. Knowledge of these torques and of the cylinder pressure provides the basis for both open loop and adaptive engine control strategies.

Abstract: A mass flow rate sensor for providing an output signal related to mass flow rate past the sensor includes a bridge circuit for generating a first mass flow rate-related signal containing temperature-related errors and mass flow rate-related errors, a resistance for generating a second signal providing temperature error correction, and a resistance for generating a third signal providing mass flow rate error correction. Electrical circuitry operatively couples the bridge circuit and resistances together to provide the output signal. A method for providing an output signal related to mass flow rate includes the steps of generating a first mass flow rate-related signal containing temperature-related errors and mass flow rate-related errors, generating a second signal providing temperature error correction, generating a third signal providing mass flow rate error correction, and combining the first, second and third signals together to provide the output signal.

Abstract: Techniques are provided for determining on-line measures of both the average torque produced by an internal combustion engine, and the torque fluctuations (relative combustion efficiencies) of the cylinders of a multiple cylinder internal combustion engine. These techniques employ knowledge of crankshaft speed at the points of fastest and slowest crankshaft speed. Also, an engine-performance monitor is proposed for determining the above noted quantities on-line. The engine-performance monitor permits monitoring of engine performance to test control strategies for both engine fuel distribution systems and ignition systems. The techniques and engine-performance monitor can also be incorporated into a feedback system for controlling the performances of the various individual cylinders of a multiple cylinder internal combustion engine. Engine crankshaft speed is the basis for the calculations required.

Abstract: An engine-performance monitor for determining the relative combustion efficiencies of the cylinders of a multiple cylinder internal combustion engine permits monitoring of engine performance to test engine fuel distribution system and ignition system control strategies. The system can also be incorporated into a feedback system for controlling the performances of the various individual cylinders of a multiple cylinder internal combustion engine.