A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are retrieved and used in combination.

A method for operating an ignition system for an internal combustion engine, including a first voltage generator and a bypass, is described. The bypass may include, for example, a boost converter for maintaining a spark generated with the aid of the first voltage generator. A speed of an internal combustion engine used with the ignition system is ascertained and the operating mode of the bypass is modified in response to the speed change.

Systems and methods for improving fuel economy in vehicles such as Class 8 trucks are provided. In some embodiments, signals indicating states of the powertrain are collected and used to generate fuel rate optimization values. Fuel rate optimization values may indicate a difference between optimum fuel flow rates and actual fuel flow rates during a vehicle drive cycle. Recorded fuel rate optimization values may be used to compare different vehicle configurations during testing, and may also be used to evaluate vehicle performance during real-world operation.

Controlling a marine engine includes operating the engine according to an initial set of mapped parameter values to achieve a first target fuel-air equivalence ratio, determining a first actual fuel-air equivalence ratio, and using a feedback controller to minimize a difference between the first target and actual ratios. Feedback controller outputs are used to populate an initial set of adapt values to adjust combustion parameter values from the initial set of mapped parameter values. The method includes transitioning to operating the engine according to a subsequent set of mapped parameter values to achieve a different target fuel-air equivalence ratio. The method includes determining a second actual fuel-air equivalence ratio, using the feedback controller to minimize a difference between the second target and actual ratios, and using feedback controller outputs to populate a subsequent set of adapt values to adjust combustion parameter values from the subsequent set of mapped parameter values.

In a control apparatus for an internal combustion engine, The ignition timing in a rich-cylinder is corrected toward a retardation side from a theoretical-MBT such that the torque generated in the rich-cylinder exceeds a torque generated in the rich-cylinder at the theoretical-MBT, and the ignition timing in a lean-cylinder is corrected toward an advancement side from the theoretical-MBT such that the torque generated in the lean-cylinder exceeds a torque generated in the lean-cylinder at the theoretical-MBT, when a temperature raising process is being executed, and the ignition timing in the rich-cylinder is corrected further toward the retardation side such that the torque generated in the rich-cylinder becomes equal to or smaller than a maximum theoretical generated torque and equal to or larger than the torque generated in the lean-cylinder at the theoretical-MBT, when the temperature raising process is being executed and the engine is in a low-load operating state.

A control methodology and apparatus for an engine suitable for use in capacitor discharge ignition systems for internal combustion engines or brushless DC motors is provided, which make use of a simple logic block to determine for instance an ignition timing advance angle or duty cycle signal based on actual engine speed versus engine control parameter data stored in a table, which is a read-only memory, preferably configurable. To minimize memory space, a small number of values of engine control parameter versus engine speed are stored in the table and the logic block determines the required engine control signal for a measured value of engine speed by an interpolation process, preferably linear interpolation.

A control system includes an ignition system configured to generate spark within a cylinder of an engine and a controller. The controller is configured to obtain a target angle of the crankshaft for an approximately 50% mass fraction burn (MFB50) and predict an ignition angle to achieve the target MFB50 angle, the ignition angle indicating an advance or retardation of spark timing. Using a combustion model, the controller is configured to generate a modeled MFB50 angle based on the predicted ignition angle and, based on the target and modeled MFB50 angles and the predicted ignition angle, determine a relationship between MFB50 angle and ignition angle. The controller is also configured to control the ignition system using the determined relationship.

Methods and systems are provided for estimating ambient humidity based on a wet bulb temperature and a dry bulb temperature during precipitation, and estimating ambient humidity based on the dry bulb temperature and not based on wet bulb temperature when precipitation is absent.

A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are retrieved and used in combination.

A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are retrieved and used in combination.