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Over the last two decades, advanced engine control systems have been developed that use cylinder pressure as the primary feedback variable. Production application has been limited by cost, reliability, and packaging difficulties associated with intrusive cylinder pressure sensors. Now, a low-cost cylinder-pressure-based engine control system has been developed that utilizes Pressure-Ratio Management (PRM) and non-intrusive cylinder pressure sensors mounted in the spark plug boss of four-valve-per-cylinder engines. The system adaptively optimizes individual-cylinder spark timing and air-fuel ratio, and overall exhaust gas recirculation (EGR) for best fuel economy and lowest emissions over the life of each vehicle. This paper presents the engine control and cylinder pressure sensor systems. Results are presented showing spark timing and EGR control, knock and misfire detection, cylinder-to-cylinder air/fuel balancing, and cold start control.

This paper presents an overview of techniques for measuring friction using bench tests and fired engines. The test methods discussed have been developed to provide efficient, yet realistic, assessments of new component designs, materials, and lubricants for in-cylinder and overall engine applications. A Cameron-Plint Friction and Wear Tester was modified to permit ring-in-piston-groove movement by the test specimen, and used to evaluate a number of cylinder bore coatings for friction and wear performance. In a second study, it was used to evaluate the energy conserving characteristics of several engine lubricant formulations. Results were consistent with engine and vehicle testing, and were correlated with measured fuel economy performance. The Instantaneous IMEP Method for measuring in-cylinder frictional forces was extended to higher engine speeds and to modern, low-friction engine designs.