Simplified Procedure for Basic Open Loop Calibration Maps in Spark Ignition Engines

One of the biggest challenges in the development of a new engine and/or control system basic calibration is the construction of initial open loop maps when component characteristic curves are not available yet. It is very common in this development phase to have cylinder air charge or fuel injector terms, which effect final commanded fuel injector pulse width (i.e., injector opening time), being assigned (compensated) to wrong calibration maps as a result of the lack of reliable component characteristic curves at the beginning of calibration development. This paper presents a practical and simplified procedure for raising the basic engine maps for cylinder air mass filling, volumetric efficiency, fuel injector static flow and offset in either an engine bench or chassis dyno. This method has proven to be accurate enough to allow continuing with the basic calibration development. Comparisons to suppliers final characteristics curves show a deviation lower than 3%. Closed loop correction shows deviations lower than 5%.